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  Subjects -> MATHEMATICS (Total: 886 journals)
    - APPLIED MATHEMATICS (72 journals)
    - GEOMETRY AND TOPOLOGY (20 journals)
    - MATHEMATICS (656 journals)
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    - NUMERICAL ANALYSIS (19 journals)
    - PROBABILITIES AND MATH STATISTICS (77 journals)

MATHEMATICS (656 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 538 Journals sorted alphabetically
Abakós     Open Access   (Followers: 4)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 3)
Academic Voices : A Multidisciplinary Journal     Open Access   (Followers: 2)
Accounting Perspectives     Full-text available via subscription   (Followers: 8)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 16)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 4)
ACM Transactions on Mathematical Software (TOMS)     Hybrid Journal   (Followers: 6)
ACS Applied Materials & Interfaces     Full-text available via subscription   (Followers: 22)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1)
Acta Mathematica     Hybrid Journal   (Followers: 11)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 5)
Acta Mathematica Vietnamica     Hybrid Journal  
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal  
Advanced Science Letters     Full-text available via subscription   (Followers: 8)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 3)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 15)
Advances in Decision Sciences     Open Access   (Followers: 5)
Advances in Difference Equations     Open Access   (Followers: 1)
Advances in Fixed Point Theory     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Linear Algebra & Matrix Theory     Open Access   (Followers: 2)
Advances in Materials Sciences     Open Access   (Followers: 16)
Advances in Mathematical Physics     Open Access   (Followers: 5)
Advances in Mathematics     Full-text available via subscription   (Followers: 10)
Advances in Numerical Analysis     Open Access   (Followers: 4)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Pure and Applied Mathematics     Hybrid Journal   (Followers: 6)
Advances in Pure Mathematics     Open Access   (Followers: 4)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2)
African Journal of Educational Studies in Mathematics and Sciences     Full-text available via subscription   (Followers: 5)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 4)
Afrika Matematika     Hybrid Journal   (Followers: 1)
Air, Soil & Water Research     Open Access   (Followers: 8)
AKSIOMA Journal of Mathematics Education     Open Access   (Followers: 1)
Al-Jabar : Jurnal Pendidikan Matematika     Open Access  
Algebra and Logic     Hybrid Journal   (Followers: 4)
Algebra Colloquium     Hybrid Journal   (Followers: 4)
Algebra Universalis     Hybrid Journal   (Followers: 2)
Algorithmic Operations Research     Full-text available via subscription   (Followers: 5)
Algorithms     Open Access   (Followers: 11)
Algorithms Research     Open Access   (Followers: 1)
American Journal of Biostatistics     Open Access   (Followers: 9)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 4)
American Journal of Mathematical Analysis     Open Access  
American Journal of Mathematics     Full-text available via subscription   (Followers: 7)
American Journal of Operations Research     Open Access   (Followers: 5)
American Mathematical Monthly     Full-text available via subscription   (Followers: 6)
An International Journal of Optimization and Control: Theories & Applications     Open Access   (Followers: 7)
Analele Universitatii Ovidius Constanta - Seria Matematica     Open Access   (Followers: 1)
Analysis     Hybrid Journal   (Followers: 2)
Analysis and Applications     Hybrid Journal   (Followers: 1)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 3)
Analysis Mathematica     Full-text available via subscription  
Annales Mathematicae Silesianae     Open Access  
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4)
Annales UMCS, Mathematica     Open Access   (Followers: 1)
Annales Universitatis Paedagogicae Cracoviensis. Studia Mathematica     Open Access  
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Data Science     Hybrid Journal   (Followers: 9)
Annals of Discrete Mathematics     Full-text available via subscription   (Followers: 6)
Annals of Mathematics     Full-text available via subscription  
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 6)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of the Alexandru Ioan Cuza University - Mathematics     Open Access  
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1)
Annals of West University of Timisoara - Mathematics     Open Access  
Annuaire du Collège de France     Open Access   (Followers: 5)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applications of Mathematics     Hybrid Journal   (Followers: 1)
Applied Categorical Structures     Hybrid Journal   (Followers: 2)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Mathematics     Open Access   (Followers: 3)
Applied Mathematics     Open Access   (Followers: 4)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 4)
Applied Mathematics - A Journal of Chinese Universities     Hybrid Journal  
Applied Mathematics Letters     Full-text available via subscription   (Followers: 1)
Applied Mathematics Research eXpress     Hybrid Journal   (Followers: 1)
Applied Network Science     Open Access   (Followers: 1)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arab Journal of Mathematical Sciences     Open Access   (Followers: 3)
Arabian Journal of Mathematics     Open Access   (Followers: 2)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 1)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 5)
Archive of Numerical Software     Open Access  
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
Arnold Mathematical Journal     Hybrid Journal   (Followers: 1)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 20)
Asia-Pacific Journal of Operational Research     Hybrid Journal   (Followers: 3)
Asian Journal of Algebra     Open Access   (Followers: 1)
Asian Journal of Current Engineering & Maths     Open Access  
Asian-European Journal of Mathematics     Hybrid Journal   (Followers: 2)
Australian Mathematics Teacher, The     Full-text available via subscription   (Followers: 7)
Australian Primary Mathematics Classroom     Full-text available via subscription   (Followers: 2)
Australian Senior Mathematics Journal     Full-text available via subscription   (Followers: 1)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Axioms     Open Access  
Baltic International Yearbook of Cognition, Logic and Communication     Open Access  
Basin Research     Hybrid Journal   (Followers: 5)
BIBECHANA     Open Access   (Followers: 1)
BIT Numerical Mathematics     Hybrid Journal  
BoEM - Boletim online de Educação Matemática     Open Access  
Boletim Cearense de Educação e História da Matemática     Open Access  
Boletim de Educação Matemática     Open Access  
Boletín de la Sociedad Matemática Mexicana     Hybrid Journal  
Bollettino dell'Unione Matematica Italiana     Full-text available via subscription   (Followers: 1)
British Journal of Mathematical and Statistical Psychology     Full-text available via subscription   (Followers: 20)
Bruno Pini Mathematical Analysis Seminar     Open Access  
Buletinul Academiei de Stiinte a Republicii Moldova. Matematica     Open Access   (Followers: 8)
Bulletin des Sciences Mathamatiques     Full-text available via subscription   (Followers: 4)
Bulletin of Dnipropetrovsk University. Series : Communications in Mathematical Modeling and Differential Equations Theory     Open Access   (Followers: 1)
Bulletin of Mathematical Sciences     Open Access   (Followers: 1)
Bulletin of the Brazilian Mathematical Society, New Series     Hybrid Journal  
Bulletin of the London Mathematical Society     Hybrid Journal   (Followers: 3)
Bulletin of the Malaysian Mathematical Sciences Society     Hybrid Journal  
Calculus of Variations and Partial Differential Equations     Hybrid Journal  
Canadian Journal of Science, Mathematics and Technology Education     Hybrid Journal   (Followers: 20)
Carpathian Mathematical Publications     Open Access   (Followers: 1)
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal  
CHANCE     Hybrid Journal   (Followers: 5)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Annals of Mathematics, Series B     Hybrid Journal  
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Mathematics     Open Access  
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Cogent Mathematics     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Collectanea Mathematica     Hybrid Journal  
College Mathematics Journal     Full-text available via subscription   (Followers: 3)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Commentarii Mathematici Helvetici     Hybrid Journal   (Followers: 1)
Communications in Contemporary Mathematics     Hybrid Journal  
Communications in Mathematical Physics     Hybrid Journal   (Followers: 1)
Communications On Pure & Applied Mathematics     Hybrid Journal   (Followers: 3)
Complex Analysis and its Synergies     Open Access   (Followers: 2)
Complex Variables and Elliptic Equations: An International Journal     Hybrid Journal  
Complexus     Full-text available via subscription  
Composite Materials Series     Full-text available via subscription   (Followers: 9)
Comptes Rendus Mathematique     Full-text available via subscription   (Followers: 1)
Computational and Applied Mathematics     Hybrid Journal   (Followers: 2)
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2)
Computational and Mathematical Organization Theory     Hybrid Journal   (Followers: 2)
Computational Complexity     Hybrid Journal   (Followers: 4)
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 4)
Computational Methods and Function Theory     Hybrid Journal  
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Concrete Operators     Open Access   (Followers: 4)
Confluentes Mathematici     Hybrid Journal  
COSMOS     Hybrid Journal  
Cryptography and Communications     Hybrid Journal   (Followers: 14)
Cuadernos de Investigación y Formación en Educación Matemática     Open Access  
Cubo. A Mathematical Journal     Open Access  
Czechoslovak Mathematical Journal     Hybrid Journal   (Followers: 1)
Demographic Research     Open Access   (Followers: 11)
Demonstratio Mathematica     Open Access  
Dependence Modeling     Open Access  
Design Journal : An International Journal for All Aspects of Design     Hybrid Journal   (Followers: 28)
Developments in Clay Science     Full-text available via subscription   (Followers: 1)
Developments in Mineral Processing     Full-text available via subscription   (Followers: 3)
Dhaka University Journal of Science     Open Access  
Differential Equations and Dynamical Systems     Hybrid Journal   (Followers: 2)
Discrete Mathematics     Hybrid Journal   (Followers: 8)
Discrete Mathematics & Theoretical Computer Science     Open Access  
Discrete Mathematics, Algorithms and Applications     Hybrid Journal   (Followers: 2)
Discussiones Mathematicae Graph Theory     Open Access   (Followers: 1)
Dnipropetrovsk University Mathematics Bulletin     Open Access  
Doklady Mathematics     Hybrid Journal  
Duke Mathematical Journal     Full-text available via subscription   (Followers: 1)
Edited Series on Advances in Nonlinear Science and Complexity     Full-text available via subscription  
Electronic Journal of Graph Theory and Applications     Open Access   (Followers: 2)
Electronic Notes in Discrete Mathematics     Full-text available via subscription   (Followers: 2)
Elemente der Mathematik     Full-text available via subscription   (Followers: 3)
Energy for Sustainable Development     Hybrid Journal   (Followers: 9)
Enseñanza de las Ciencias : Revista de Investigación y Experiencias Didácticas     Open Access  
Ensino da Matemática em Debate     Open Access  
Entropy     Open Access   (Followers: 5)
ESAIM: Control Optimisation and Calculus of Variations     Full-text available via subscription   (Followers: 1)
European Journal of Combinatorics     Full-text available via subscription   (Followers: 5)
European Journal of Mathematics     Hybrid Journal   (Followers: 1)
European Scientific Journal     Open Access   (Followers: 2)
Experimental Mathematics     Hybrid Journal   (Followers: 4)
Expositiones Mathematicae     Hybrid Journal   (Followers: 2)
Facta Universitatis, Series : Mathematics and Informatics     Open Access  
Fasciculi Mathematici     Open Access  
Finite Fields and Their Applications     Full-text available via subscription   (Followers: 4)
Fixed Point Theory and Applications     Open Access   (Followers: 1)

        1 2 3 4 | Last

Journal Cover ChemSusChem
  [SJR: 2.649]   [H-I: 88]   [7 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1864-5631 - ISSN (Online) 1864-564X
   Published by John Wiley and Sons Homepage  [1579 journals]
  • Artificial Photosynthetic Systems for CO2 Reduction: Progress on Higher
           Efficiency with Cobalt Complexes as Catalysts
    • Authors: Feng Wang
      Abstract: The conversion of CO2 to fuels or value-added chemicals is currently a field of great research interest. Molecular cobalt catalysts had long been used as mediators of CO2 reduction transformation. In this mini-review, the cobalt complex-based photocatalytic and photoelectrocatalytic systems towards CO2 reduction are reviewed. Progress on the design of new molecular cobalt catalysts and their performance in photocatalysis is discussed and summarized.
      PubDate: 2017-10-21T11:20:32.689206-05:
      DOI: 10.1002/cssc.201701385
       
  • Imidazolium- and triazine-based porous organic polymers for heterogeneous
           catalytic conversion of CO2 into cyclic carbonates.
    • Authors: Hong Zhong; Yanqing Su, Xingwei Chen, Xiaoju Li, Ruihu Wang
      Abstract: Carbon dioxide (CO2) adsorption and concomitant catalytic conversion into useful chemicals are promising approaches to alleviate energy crisis and global warming. It is highly desirable for developing new types of heterogeneous catalytic materials containing CO2-philic groups and catalytic active sites for CO2 chemical transformation. Here, we present an imidazolium- and triazine-based porous organic polymer with counter chloride anion (IT-POP-1). The porosity and CO2 affinity of IT-POP-1 may be modulated at molecular level through facile anion exchange strategy. Compared with the post-modified polymers with iodide and hexafluorophosphate anions, IT-POP-1 possesses the highest surface area and the best CO2 uptake capacity with excellent adsorption selectivity over N2. The roles of the task-specific components, such as triazine, imidazolium, hydroxyl and counter anions, in CO2 absorption and catalytic performance were illustrated. IT-POP-1 exhibits the highest catalytic activity and excellent recyclability in solvent- and additive-free cycloaddition reaction of CO2 with epoxides.
      PubDate: 2017-10-20T03:20:37.864441-05:
      DOI: 10.1002/cssc.201701821
       
  • Structure-Activity and Stability Relationships for Cobalt Polypyridyl
           based Hydrogen Evolving Catalysts in Water
    • Authors: Stephan Schnidrig; Cyrill Bachmann, Peter Müller, Nicola Weder, bernhard Spingler, Evelyne Joliat-Wick, mathias Mosberger, johannes windisch, roger alberto, Benjamin Probst
      Abstract: A series of eight new and three known cobalt polypyridyl based hydrogen evolving catalysts (HEC), with distinct electronic and structural differences are benchmarked in photocatalytic runs in water. Methylene-bridged bis-bipyridyl is the preferred scaffold, both in terms of stability and rate. For a cobalt complex of the tetradentate, methanol bridged bis-pyridyl-bipyridyl [CoIIBr(tpy)]Br (1a) a detailed mechanistic picture is obtained by combining electrochemistry, spectroscopy and photocatalysis. In the acidic branch, a proton coupled electron transfer (PCET), assigned to formation of CoIII-H, is found upon reduction of CoII, in line with a pKa(CoIII-H) of ~7.25. Subsequent reduction (-0.94 V vs NHE) and protonation close the catalytic cycle. Methoxy substitution on the bipyridyl scaffold results in the expected cathodic shift of the reduction, but fails to change the pKa(CoIII-H). An analysis of the outcome of the benchmarking in view of this postulated mechanism is given along with an outlook for design criteria for new generations of catalysts.
      PubDate: 2017-10-19T20:50:51.959743-05:
      DOI: 10.1002/cssc.201701511
       
  • Imidazolium based Ionic liquids as efficient reagents for lignin C-O bond
           cleavage
    • Authors: Marina Thierry; Amel Majira, Bruce Pégot, Laurent Cézard, Flavien Bourdreux, Gilles Clément, François Perreau, Stéphanie Boutet-Mercey, Patrick Diter, Giang Vo-Thanh, Catherine Lapierre, Paul-Henri Ducrot, Emmanuel Magnier, Stephanie Baumberger, betty cottyn
      Abstract: Lignin chemical demethylation in ionic liquids was investigated using pure lignin-model monomers and dimer together with dioxan isolated lignins from poplar, miscanthus and maize. Different methylimidazolium ionic liquids (ILs) were compared, according to two different heating processes, microwave irradiation and conventional heating in sealed tube. The conversion yield and influence of the treatments on lignin structure were assessed by 31P NMR, size exclusion chromatography and thioacidolysis. The acidic IL [HMIM][Br] was shown to be an effective combination solvent/reagent for the demethylation and even depolymerisation of lignin. The relatively mild reaction conditions, the clean work-up, and the ability to reuse the ionic liquid made the described procedure an attractive and new green method for the lignin conversion to produce phenol-rich lignin oligomers.
      PubDate: 2017-10-19T04:45:35.953679-05:
      DOI: 10.1002/cssc.201701668
       
  • Direct coupling of thermo- and photo-catalytic conversion of
           CO₂-H₂O to fuels
    • Authors: Li Zhang; Guoguo Kong, Yaping Meng, Jinshu Tian, Lijie Zhang, Shaolong Wan, Jingdong Lin, Yong Wang
      Abstract: Photocatalytic CO₂ reduction into renewable hydrocarbon solar fuels is considered as a promising strategy to simultaneously address the global energy and environmental issues. This article focuses on the direct coupling of photocatalytic water splitting and thermo-catalytic hydrogenation of CO₂ in the conversion of CO₂-H₂O to fuels. Specifically, it was found that direct coupling of thermo- and photo-catalysis over Au-Ru/TiO₂ leads to 15 times higher activity (358 K, with ~99% CH₄ selectivity) in the conversion of CO₂-H₂O to fuels than that of photo-catalytic water splitting. This is ascribed to the promoting effect of thermo-catalytic hydrogenation of CO₂ by hydrogen atoms generated in situ by photo-catalytic water splitting.
      PubDate: 2017-10-18T01:15:56.517182-05:
      DOI: 10.1002/cssc.201701472
       
  • Iron-Catalyzed C−O Bond Activation: Opportunity for Sustainable
           Catalysis
    • Authors: Elwira Bisz; Michal Szostak
      Abstract: The Front Cover shows just a few of the many products accessible through iron-catalyzed cross-coupling reactions by selective C−O cleavage. In view of the natural abundance, ready availability, low price, and very low toxicity of iron, it offers distinct environmental advantages when compared to other metals. The combination of sustainable iron catalysis with environmentally-friendly electrophiles has led to highly attractive alternatives to traditional cross-coupling reactions by using easily accessible oxygen-based electrophiles as substrates, opening new possibilities for the development of a wide range of unprecedented reactions. More information can be found in the Minireview by Bisz and Szostak.
      PubDate: 2017-10-16T08:45:30.014418-05:
      DOI: 10.1002/cssc.201701887
       
  • Iron-Catalyzed C−O Bond Activation: Opportunity for Sustainable
           Catalysis
    • Authors: Elwira Bisz; Michal Szostak
      Abstract: Invited for this month′s cover is the group of Michal Szostak at the University of Opole. The image shows how the oxygen-based electrophiles can be merged with sustainable iron catalysis to create an environmentally friendly platform for cross-coupling. The Minireview itself is available at 10.1002/cssc.201701287.“Iron is one the few metals that have evolved to provide indispensable tools…” This and more about the story behind the research that inspired the Cover image is presented in the Cover Profile. Read the full text of the corresponding research at 10.1002/cssc.201701287. View the Front Cover here: 10.1002/cssc.201701887.
      PubDate: 2017-10-13T04:36:15.964019-05:
      DOI: 10.1002/cssc.201701888
       
  • Electrochemical Behavior of Pyridinium and N-Methyl Pyridinium Cations in
           Aqueous Electrolyte for CO2 Reduction
    • Authors: Estelle Lebègue; Julia Agullo, Daniel Bélanger
      Abstract: We examined the electrochemical reduction of aqueous pyridinium and N-methyl pyridinium ions in the absence and presence of CO2 and studied the electrolysis reaction products on glassy carbon, Au and Pt electrodes. Unlike pyridinium, N-methyl pyridinium is not electroactive at the Pt electrode. The electrochemical reduction of the two pyridine derivatives was found to be irreversible on glassy carbon. These results confirmed the essential role of the N-H bond of the pyridinium cation. In contrast, the electrochemical response of N-methyl pyridinium ion at glassy carbon electrode suggests that a specific interaction seems to occur between the glassy carbon surface and the aromatic ring of the pyridinium derivative. For all electrodes, an enhancement of current was observed in presence of CO2. However, NMR analyses of the solutions following electrolysis have not shown the formation of methanol or other possible by-products of the reduction of CO2 in the presence of both pyridinium derivative ions.
      PubDate: 2017-10-12T12:25:22.027244-05:
      DOI: 10.1002/cssc.201701745
       
  • Encapsulating Co2P@C Core-Shell Nanoparticles in Porous Carbon Sandwich: a
           Nitrogen and Phosphorus Dual-Doped PH-Universal Electrocatalysts for
           High-efficient Hydrogen Evolution
    • Authors: YuanYuan Yang; XiongYi Liang, Feng Li, ShuWen Li, XinZhe Li, Siu-Pang Ng, Chi-Man Lawrence Wu, Rong Li
      Abstract: A new, highly-efficient and pH-universal sandwich-architecture HER electrocatalysts, constructed by 0-dimensional N and P dual-doped core-shell Co2P@C nanoparticles embedded into a 3-dimensional porous carbon sandwich (Co2P@N,P-C/CG), was synthesized by a facile two-step method of hydrothermal carbonization (HTC) and pyrolysis. Owing to the synergistic effect of N, P-codoped Co2P@C core-shell and sandwich-nanostructural substrates, it increases the interfacial electron transfer rate and the number of active sites. Because of the presence of high surface area and large porous sizes, it improves the mass transfer dynamics. This nanohybrid shows remarkable electrocatalytic activity toward the HER in wide pH value, with good stability. The computational study and experiments reveal that the carbon atoms closed to N and P heteroatoms dopants on the shell of Co2P@N,P-C are the effective active sites for HER catalyst, and Co2P and N, P dopants synergistically optimize the binding free energy of H* on the active sites.
      PubDate: 2017-10-12T10:25:28.977874-05:
      DOI: 10.1002/cssc.201701705
       
  • Boosting the Supercapacitance of Nitrogen-Doped Carbon by Tuning Surface
           Functionalities
    • Authors: Jasper Biemolt; Ilse M. Denekamp, Thierry K. Slot, Gadi Rothenberg, David Eisenberg
      Abstract: The Cover Feature shows high-energy supercapacitors as envisioned by Itamar Daube. The capacitance of nitrogen-doped carbon could be tweaked and considerably enhanced considerably by orthogonal optimization of both its structure and surface chemistry. The first is achieved by varying pyrolysis conditions and the latter through an acidic surface treatment. When following the stepwise evolution of surface chemistry with X-ray photoelectron spectroscopy, the evolution of both oxygen- and oxygen-nitrogen surface functionalities can be followed. These functionalities boost pseudocapacitive reactions that significantly contribute to the supercapacitance of the material. More information can be found in the Full Paper by Biemolt et al.
      PubDate: 2017-10-12T06:41:02.705583-05:
      DOI: 10.1002/cssc.201701889
       
  • Dendritic Fibrous Nanosilica for Catalysis, Energy Harvesting, Carbon
           Dioxide Mitigation, Drug Delivery, and Sensing
    • Authors: Ayan Maity; Vivek Polshettiwar
      Abstract: The Cover Feature shows technologies in the fields of energy, environment, and health in which morphology-controlled nanomaterials such as silica could play a crucial role. Nanosilicas can be synthesized and designed with a large variety of sizes, shapes, morphologies, and textural properties (surface area, pore size and pore volume) to meet the challenges of the fields. One notable material is the dendritic fibrous nanosilica. This material has a unique fibrous morphology and a high surface area with improved accessibility to the internal surface, tunable pore size and volume, controllable particle size, and importantly, which makes it useful for a variety of applications. More information can be found in the Review by Maity and Polshettiwar.
      PubDate: 2017-10-12T06:41:00.645886-05:
      DOI: 10.1002/cssc.201701890
       
  • Dry Reforming of Methane in a Gliding Arc Plasmatron: Towards a Better
           Understanding of the Plasma Chemistry
    • Authors: Emelie Cleiren; Stijn Heijkers, Marleen Ramakers, Annemie Bogaerts
      Abstract: The Cover Feature shows a gliding arc plasmatron (a new type of plasma reactor) that can convert methane through dry reforming into useful fuels and compounds. This process can fit into the “cradle-to-cradle” concept, as waste (CO2 and CH4) can be converted into raw materials (syngas) for the chemical industry using renewable energy. A non-thermal plasma can accomplish this reaction in an energy efficient way because only the electrons are heated and they activate the gas molecules. A gliding-arc plasma is very promising as it operates at atmospheric pressure and yields a good energy efficiency. More information can be found in the Full Paper by Cleiren et al.
      PubDate: 2017-10-12T06:40:52.44639-05:0
      DOI: 10.1002/cssc.201701891
       
  • Catalytic, Conductive Bipolar Membrane Interfaces via Layer-by-Layer
           Deposition for the Design of Membrane-Integrated Artificial Photosynthesis
           Systems
    • Authors: Michael B McDonald; Michael Freund, Paula T Hammond
      Abstract: In the presence of an electric field, bipolar membranes (BPMs) are capable of initiating water disassociation (WD) within the interfacial region, which can make water splitting for renewable energy in the presence of a pH gradient possible. In addition to WD catalytic efficiency, there is also need for electronic conductivity in this region for membrane-integrated artificial photosynthesis (AP) systems. Graphene oxide (GO) has been shown to catalyze WD and to be controllably reduced resulting in electronic conductivity. Layer-by-layer (LbL) film deposition has been employed to improve GO film uniformity in the interfacial region to enhance WD catalysis and through the addition of a conducting polymer in the process, add electronic conductivity in a hybrid film. Three different deposition methods were tested in order to optimize conducting polymer synthesis with oxidant in a metastable solution, and yield the best film properties. It was found that an approach including substrate dipping in a concentration of oxidant corresponding to the amount expected to incorporate into a film provides the most predictable film growth and smoothest films, as determined by UV-visible spectrometry and AFM/SEM, respectively, while dipping when the oxidant is in excess or co-spraying the oxidant and monomer produce non-uniform, heterogeneous films. These superior films are electronically conductive, producing a membrane ohmic drop of ~100 mV, which is acceptable for AP a
      PubDate: 2017-10-10T13:50:22.778388-05:
      DOI: 10.1002/cssc.201701397
       
  • Ligand Substituents Govern the Efficiency and Mechanistic Path of Hydrogen
           Production with [Cp*Rh] Catalysts
    • Authors: Wade Henke; Davide Lionetti, William Moore, Julie Hopkins, Victor Day, James Blakemore
      Abstract: Abstract: We demonstrate that [Cp*Rh] complexes bearing substituted 2,2´-bipyridyl ligands are effective hydrogen-evolution catalysts (Cp* = η5-pentamethylcyclopentadienyl). Disubstitution (at the 4 and 4´ positions) of the bipyridyl ligand (namely -tBu, -H, and -CF3) modulates the catalytic overpotential, in part due to involvement of reduced ligand character in formally rhodium(I) intermediates. These reduced species are synthesized and isolated here; protonation results in formation of complexes bearing the unusual η4-pentamethylcyclopentadiene ligand, and the properties of these protonated intermediates further govern catalytic performance. Electrochemical studies suggest that multiple mechanistic pathways are accessible, and that the operative pathway depends on applied potential and solution conditions. Taken together, these results suggest synergy in metal-ligand cooperation that modulates the mechanisms of fuel-forming catalysis with organometallic compounds bearing multiple non-innocent ligands.
      PubDate: 2017-10-10T09:20:38.002909-05:
      DOI: 10.1002/cssc.201701416
       
  • Benchmarking Water Oxidation Catalysts Based on Iridium Complexes: Clues
           and Doubts on the Nature of Active Species
    • Authors: Alceo Macchioni; Gabriel Menendez Rodriguez, Giordano Gatto, Cristiano Zuccaccia
      Abstract: Water Oxidation (WO) is a central reaction in the photo- and electro-synthesis of fuels. Iridium complexes have been successfully exploited as water oxidation catalysts (WOCs) with remarkable performances. Herein we report a systematic study aimed at benchmarking well-known Ir WOCs, when NaIO4 is used to drive the reaction. In particular, the following complexes were studied: cis-[Ir(ppy)2(H2O)2]OTf (ppy = 2-phenylpyridine) 1, [Cp*Ir(H2O)3]NO3 (Cp* = cyclopentadienyl anion) 2, [Cp*Ir(bzpy)Cl] (bzpy = 2-benzoylpyridine) 3, [Cp*IrCl2(Me2-NHC)] (NHC = N-heterocyclic carbene) 4, [Cp*Ir(pyalk)Cl] (pyalk = 2-pyridine-isopropanoate) 5, [Cp*Ir(pic)NO3] (pic = 2-pyridine-carboxylate) 6, [Cp*Ir{(P(O)(OH)2}3]Na 7, and mer-[IrCl3(pic)(HOMe)]K 8. Their reactivity was compared with that of IrCl3.nH2O 9 and [Ir(OH)6]2- 10. Most measurements were carried out in phosphate buffer (0.2 M), where 2, 4, 5, 6, 7, and 10 showed very high activity (yield close to 100%, TOF up to 554 min-1 with 10, the highest ever observed for a WO driven by NaIO4). The found order of activity is: 10> 2 ≈ 4> 6> 5> 7> 1> 9> 3> 8. Clues concerning the molecular nature of the active species were obtained, whereas its exact nature remains doubtfully.
      PubDate: 2017-10-10T02:55:51.874317-05:
      DOI: 10.1002/cssc.201701818
       
  • Nitrogen-Doped Carbon Nanotubes Derived from Metal-Organic Frameworks for
           Potassium-Ion Battery Anodes
    • Authors: Peixun Xiong; Xinxin Zhao, Yunhua Xu
      Abstract: To tackle the issue of the poor rate capability of graphite anodes for potassium-ion batteries (KIBs), nitrogen-doped carbon nanotubes (NCNTs) with an edge-open layer-alignment structure were synthesized using a simple and scalable approach of pyrolyzing cobalt-containing metal-organic frameworks. The unique structure enables a facile and fast intercalation of K ions. As anodes of KIBs, the NCNTs demonstrated a superior rate capability by a high capacity retention of 102 mA h g-1 at a high current density of 2000 mA g-1 and a good stability without obvious capacity loss over 500 cycles at 2000 mA g-1. Our findings would help to develop high performance anode materials for potassium-ion batteries as large-scale and low-cost energy storage systems.
      PubDate: 2017-10-10T00:50:22.203168-05:
      DOI: 10.1002/cssc.201701759
       
  • Factors Influencing the Mechanical Properties of Formamidinium Lead
           Halides and Related Hybrid Perovskites
    • Authors: Shijing Sun; Furkan H. Isikgor, Zeyu Deng, Fengxia Wei, Gregor Kieslich, Paul D. Bristowe, Jianyong Ouyang, Anthony K. Cheetham
      Abstract: Invited for this month′s cover is the group of Prof. Tony Cheetham and Dr. Paul Bristowe at the University of Cambridge, in collaboration with Dr. Gregor Kieslich at TU Munich and Prof. Jianyong Ouyang at the National University of Singapore. The Cover image shows how the structural–mechanical properties of hybrid perovskites can be determined by using a combination of nanoindentation measurements and crystallographic studies. The Communication itself is available at 10.1002/cssc.201700991.“We are working on other important perovskite families, such as systems based on formate and hypophosphite linkers…” This and more about the story behind the research that inspired the Cover image is presented in the Cover Profile. Read the full text of the corresponding research at 10.1002/cssc.201700991. View the Front Cover here: 10.1002/cssc.201701761.
      PubDate: 2017-10-09T05:05:25.360918-05:
      DOI: 10.1002/cssc.201701762
       
  • Light-Harvesting Organic Nanocrystals Capable of Photon Upconversion
    • Authors: Li Li; Yi Zeng, Tianjun Yu, Jinping Chen, Guoqiang Yang, Yi Li
      Abstract: Harvesting and converting low energy photons to higher ones through upconversion have great potential in solar energy conversion. Herein, we demonstrate a light-harvesting nanocrystal assembled by 9,10-distyrylanthracene and palladium(II) meso-tetraphenyltetrabenzoporphyrin as the acceptor and the sensitizer, respectively, in which red-to-green upconversion is achieved under incoherent excitation of low power density and the upconversion quantum yield of 0.29 ± 0.02% is obtained upon excitation with 640 nm laser of 120 mW cm¯². The well-organized packing of acceptor molecules with aggregation-induced emission in the nanocrystals dramatically reduces the nonradiative decay of the excited acceptor, benefits the TTA upconversion and guides out the consequent upconverted emission. This work provides a straightforward strategy to develop light-harvesting nanocrystals based on TTA upconversion, which is attractive for energy conversion and photonic applications.
      PubDate: 2017-10-09T01:50:41.016176-05:
      DOI: 10.1002/cssc.201701389
       
  • Iridium Complexes with Proton-Responsive Azole-Type Ligands as Effective
           Catalysts for CO2 Hydrogenation
    • Authors: Mehmed Zahid Ertem; Yuki Suna, Yuichiro Himeda, James T Muckerman, Etsuko Fujita
      Abstract: Pentamethylcyclopentadienyl iridium (Cp*Ir) complexes with bidentate ligands consisting of a pyridine ring and an electron-rich diazole ring were prepared. Their catalytic activity towards CO2 hydrogenation in 2.0 M KHCO3 aqueous solutions (pH 8.5) at 50 °C, under 1.0 MPa CO2/H2 (1:1) have been reported as an alternative to photo- and electrochemical CO2 reduction. Bidentate ligands incorporating an electron-rich diazole ring improved the catalytic performance of the Ir complexes compared to the bipyridine ligand. Complexes 2, 4 and 6, possessing both a hydroxy group and an uncoordinated NH group, which are proton-responsive and capable of generating pendent-bases in basic media, recorded high initial TOF values of 1300 h-1, 1550 h-1 and 2000 h-1, respectively. Spectroscopic and computational investigations revealed that the reversible deprotonation changes the electronic properties of the complexes and causes interactions between pendent base and substrate and/or solvent water molecules, resulting in the high catalytic performance in basic media.
      PubDate: 2017-10-06T11:10:44.06327-05:0
      DOI: 10.1002/cssc.201701676
       
  • Catalytic Hydrogenation of Macroalgae-derived Alginic Acid into Sugar
           Alcohols
    • Authors: Chunghyeon Ban; Wonjin Jeon, Hee Chul Woo, Do Heui Kim
      Abstract: Alginic acid, a major constituent of macroalgae, was hydrogenated into sugar alcohols over carbon-supported noble metals for the first time. Mannitol and sorbitol were mainly produced via the catalytic hydrogenation of alginic acid, which consists of two epimeric uronic acids. The main reaction pathway is the consecutive hydrogenation of aldehyde- and carboxyl-end of alginic acid dimers followed by the cleavage of C-O-C linkage into monomeric units via hydrolysis. The highest yield of C6 sugar alcohols is 61% (sorbitol: 29%, mannitol: 28%, and galactitol: 4%). The low value of sorbitol to mannitol ratio differs to the case of cellulose hydrogenation due to the composition of alginic acid and isomerization between sugar alcohols under the catalytic system. Such a new and green route to produce sugar alcohols from alginic acid would provide opportunities to diversify biomass resources.
      PubDate: 2017-10-06T03:05:56.427648-05:
      DOI: 10.1002/cssc.201701860
       
  • Solid Aluminum Borohydrides as Perspective Hydrogen Stores
    • Authors: Iurii Dovgaliuk; Damir Safin, Nikolay Tumanov, Fabrice Morelle, Adel Moulai, Radovan Černý, Zbigniew Łodziana, Michel Devillers, Yaroslav Filinchuk
      Abstract: Metal borohydrides are intensively researched as high capacity hydrogen storage materials. Aluminum is a cheap, light and abundant element and Al3+ can be a template for reversible dehydrogenation. However, Al(BH4)3, containing 16.9 weight % of hydrogen, has a low boiling point, is explosive on air and has poor storage stability. We present a new family of mixed-cation borohydrides M[Al(BH4)4], all solid at ambient conditions. Their thermal decomposition properties show diverse behavior: Al(BH4)3 is released for M = Li+, Na+, while heavier derivatives evolve hydrogen and diborane. NH4[Al(BH4)4], containing protic and hydridic hydrogens, has the lowest decomposition temperature of 35 °C and yields Al(BH4)3∙NHBH and hydrogen. The decomposition temperatures, correlated with cations' ionic potential, show that M[Al(BH4)4] are in the most practical stability window. This family of solids with convenient and versatile properties puts aluminum borohydride chemistry in the mainstream of the hydrogen storage research, e.g. for the development of reactive hydride composites with an increased hydrogen content.
      PubDate: 2017-10-05T12:05:36.497016-05:
      DOI: 10.1002/cssc.201701629
       
  • Cationic Vacancy Defects in Iron Phosphide: A Promising Route toward
           Efficient and Stable Hydrogen Evolution by Electrochemical Water Splitting
           
    • Authors: Wai Ling Kwong; Eduardo Gracia-Espino, Cheng Choo Lee, Robin Sandström, Thomas Wågberg, Johannes Messinger
      Abstract: Engineering the electronic properties of transition metal phosphides has shown great effectiveness in improving their intrinsic catalytic activity for the hydrogen evolution reaction (HER) in water splitting applications. Herein, we report for the first time, the creation of Fe vacancies as an approach to modulate the electronic structure of iron phosphide (FeP). The Fe vacancies were produced via chemical leaching of Mg that was introduced into FeP as 'sacrificial dopant'. The obtained Fe-vacancy-rich FeP nanoparticulate films, which were deposited on Ti foil, shows excellent HER activity as compared to pristine FeP and Mg-doped FeP, achieving a current density of 10 mA cm-2 at overpotentials of 108 mV in 1 M KOH and 65 mV in 0.5 M H2SO4, with a near-100% Faradaic efficiency. Our theoretical and experimental analyses reveal that the improved HER activity originates from the presence of Fe vacancies, which lead to a synergistic modulation of the structural and electronic properties that result in a near optimal hydrogen adsorption free energy and enhanced proton trapping. The success in catalytic improvement via the introduction of cationic vacancy defects has not only demonstrated the potential of Fe-vacancy-rich FeP as highly efficient, earth abundant HER catalyst, but also opened up an exciting pathway for activating other promising catalysts for electrochemical water splitting.
      PubDate: 2017-10-05T01:54:31.676097-05:
      DOI: 10.1002/cssc.201701565
       
  • Recent Advances in Photoelectrochemical Applications of Silicon Materials
           for Solar-to-Chemicals Conversion
    • Authors: Jingying Shi; Dou dou Zhang, Wei Zi, Peng peng Wang, Sheng zhong Liu
      Abstract: Photoelectrochemical (PEC) technology for the conversion of solar energy to chemicals requires cost-effective photoelectrodes to efficiently and stably drive anodic and/or cathodic half-reactions to complete the overall reactions for storing solar energy in chemical bonds. The shared properties among semiconducting photoelectrodes and photovoltaic (PV) materials are light absorption and charge separation and charge transfer. Earth-abundant silicon materials have been widely applied in the PV industry, demonstrating their efficiency as alternative photoabsorbers for photoelectrodes. Many efforts have been made to fabricate silicon photoelectrodes with enhanced performance, and significant progress has been achieved in recent years. In this review, we summarize the recent developments of crystalline and thin-film silicon-based photoelectrodes (including amorphous, microcrystalline and nanocrystalline silicon) immersed in aqueous solution for PEC hydrogen production from water splitting, as well as applications in PEC CO2 reduction and PEC regeneration of discharged species in redox flow batteries. We believe that silicon is an ideal material for the cost-effective production of solar chemicals through PEC methods.
      PubDate: 2017-10-04T14:05:53.920095-05:
      DOI: 10.1002/cssc.201701674
       
  • Niobium Doped Lanthanum Strontium Ferrite as A Redox Stable and
           Sulfur-Tolerant Anode for Solid Oxide Fuel Cells
    • Authors: Zhe Lü; Jingwei Li, Bo Wei, Zhiqun Cao, Xing Yue, Yaxin Zhang
      Abstract: A novel Nb-doped lanthanum strontium ferrite perovskite oxide La0.8Sr0.2Fe0.9Nb0.1O3-δ (LSFNb) is evaluated as anode material of solid oxide fuel cell (SOFC). The effects of Nb partial substitution on the crystal structure, electrical conductivity and valence of Fe ions are studied. A good structural stability of LSFNb in severe reducing atmosphere at 800 °C is found, suggesting that high valent Nb can effectively promote the stability of lattice structure. The ratio of Fe2+ increases after Nb doping as confirmed by the results of XPS. The maximum power density of a thick Sc-stabilized zirconia (ScSZ) electrolyte supported single cell reached 241.6 mW·cm-2 at 800 °C using H2 as fuel. The cell exhibited excellent stability for continuously 100 h operation without detectable degeneration. SEM images clearly revealed the exsolutions on LSFNb surface after operation. Meanwhile, LSFNb particles agglomerated obviously during long-term stability test. Impedance spectra suggested that both LSFNb anode and (La0.75Sr0.25)0.95MnO3-δ (LSM)/ScSZ cathode exhibited an activation process during long-term test, through which the ability of charge transfer increases obviously. Meanwhile, low-frequency resistance (RL) mainly attributed by anode (80%) significantly increased, probably due to the agglomeration of LSFNb particles. The LSFNb anode exhibits excellent anti-sulfuring poisoning ability and redox stability. These results demonstrate that LSFNb is a promising anode material for SOFC.
      PubDate: 2017-10-04T08:15:30.791593-05:
      DOI: 10.1002/cssc.201701638
       
  • Designing CdS mesoporous networks on MOF derived Co-C@Co9S8 double-shelled
           nanocages as a redox-mediator-free Z-scheme photocatalyst with superior
           photocatalytic efficiency
    • Authors: D. Amaranatha Reddy; Hanbit Park, Madhusudana Gopannagari, Eun Hwa Kim, Seunghee Lee, D. Praveen Kumar, Tae Kyu Kim
      Abstract: Designing porous nanostructures with unprecedented functions and an effective ability to harvest the maximum energy region of the solar spectrum and suppress the charge-carrier recombination rate is offering promising potential for sustainable energy production. Herein, we report a new, highly active, noble-metal-free, and redox-mediator-free Z-scheme photocatalyst, CdS/Co-C@Co9S8, for H2 production through water splitting under solar irradiation. The designed photocatalytic system contains open 3D CdS mesopores as a light absorber for wider solar light harvesting. Metal-organic-framework-derived cobalt nanocrystal-embedded few-layered carbon@Co9S8 double-shelled nanocages were used as a co-semiconductor to hamper the photo charge-carrier recombination by accelerating the photogenerated electrons and holes from the other semiconductor. The optimized catalyst shows a H2 evolution rate of 26.69 mmol·g-1·h-1 under simulated solar irradiation, which is 46 times higher than that of as-synthesized CdS mesoporous nanostructures. The apparent quantum yield reached 7.82 % at λ=425 nm in 5 h. The spectacular photocatalytic activity of CdS/Co@C-Co9S8 reflects the favorable suppression of the charge-carrier recombination rate, as determined by photoluminescence, photocurrent, and impedance analyses. We believe that the findings reported here may inspire the design of novel noble-metal-free porous nanohybrids for sustainable H2 production.
      PubDate: 2017-10-03T07:35:47.447998-05:
      DOI: 10.1002/cssc.201701643
       
  • Flower-like nickel phosphide microballs assembled by nanoplates with
           exposed high energy (001) facet: efficient electrocatalyst for hydrogen
           evolution reaction
    • Authors: Honglei Wang; Ying Xie, Hongshuai Cao, Yanchao Li, Lin Li, Zhikun Xu, Xiuwen Wang, Ni Xiong, Kai Pan
      Abstract: Fabrication of low-cost and earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) over a broad pH range is attracting the researcher attention. In this work, a facile precursor route is developed to synthesize flower-like nickel phosphide microballs with a diameter of ca. 12 μm. With controllable phosphorization temperature, the flower-like nickel phosphide microballs with different crystalline structures (Ni5P4 and Ni2P) could be easily obtained. This hierarchical structure possessed two merits for enhanced HER, the fast vectorial electron transfer path along the building block nanoplates and enhanced inherent catalytic activity of each active site for high energy (001) facets. So, flower-like Ni5P4 microballs displayed an excellent electrocatalytic activity for HER with a low overpotential (η) of 35.4 mV to reach current densities of 10 mA cm-2, and a smaller Tafel slope of 48 mV·dec-1 in acid solution. In addition, it showed an excellent activity in 1 M KOH with a η of 47 mV at 10 mA cm-2. The density functional theory indicated that the free energy of hydrogen adsorbed on Ni site of Ni5P4 was 0.152 eV, which was smaller than that of Ni site of Ni2P (0.182 eV). So, flower-like Ni5P4 microballs possessed better HER activity than Ni2P, which is consistent with our HER data. This hierarchical structure with exposed high energy (001) facets paves a new way to design and synthesize a low-cost and high-performance catalyst for HER.
      PubDate: 2017-10-02T21:26:10.787902-05:
      DOI: 10.1002/cssc.201701647
       
  • Electrocatalytic Metal-Organic Frameworks for Energy Applications
    • Authors: Courtney A Downes; Smaranda C Marinescu
      Abstract: With global energy demand expected to rise drastically over the next several decades, the development of a sustainable energy system to meet this rise is paramount. Renewable energy sources can be coupled with electrochemical conversion processes to store energy in chemical bonds. To promote these difficult transformations, electrocatalysts that operate at high conversion rates and efficiency are required. Metal-organic frameworks (MOFs) have emerged as a promising class of materials, however, the insulating nature of MOFs has limited their application as electrocatalysts. The recent development of conductive MOFs has led to several electrocatalytic MOFs that display activity comparable to the best performing heterogeneous catalysts. Although many electrocatalytic MOFs exhibit low activity and stability, the few successful examples highlight the possibility of MOF electrocatalysts as replacements for noble-metal based catalysts in commercial energy converting devices. We review here the use of pristine MOFs as electrocatalysts to facilitate important energy-related reactions.
      PubDate: 2017-10-02T12:15:38.010199-05:
      DOI: 10.1002/cssc.201701420
       
  • The enhanced photocatalytic hydrogen evolution of NiCoP/g-C3N4 with the
           improved separation efficiency and charge transfer efficiency
    • Authors: Lingling Bi; Xupeng Gao, Lijing Zhang, Dejun Wang, Xiaoxin Zou, Tengfeng Xie
      Abstract: NiCoP has caused wide attention in the field of electrocatalysis, while there is little concern on photocatalysis study and its photocatalytic mechanism. Herein we reported a simple one-pot synthesis method of NiCoP/g-C3N4 as highly efficient photocatalyst for hydrogen production from water for the first time. Remarkably, the excellent photocatalytic activity is obtained for the 50 mg NiCoP/g-C3N4 (1643 molg-1h-1), which is 21 times higher than that of bare g-C3N4. The excellent performance is due to the synergistic effect of the improved separation efficiency and the effective charge transfer efficiency. The photogenerated charge behavior is characterized by the surface photovoltage, the transient photovoltage and the photoluminescence spectroscopy. The photogenerated charge transport property is researched by the electrochemical impedance spectroscopy and polarization curve. Moreover, the effective charge transfer efficiency was measured according to the mimetic apparent quantum yield. Specifically, the novel SPV and TPV measurements that added 10 vol% triethanolamine-water solution into the testing system were measured to simulate the real atmosphere for photocatalytic reaction, which can directly provide the actual photogenerated charge transfer process. This work may provide an efficient theoretical basis to design transition metal phosphide cocatalyst modified photocatalysts. Finally, the possible photocatalytic mechanism was proposed and discussed in detail.
      PubDate: 2017-10-02T08:20:20.452586-05:
      DOI: 10.1002/cssc.201701574
       
  • Level alignment as a descriptor for semiconductor/catalyst systems in
           
    • Authors: Franziska Hegner; Drialys Cardenas-Morcoso Cardenas-Morcoso, Sixto Gimenez, Nuria Lopez, Jose Ramon Galan-Mascaros
      Abstract: The realization of artificial photosynthesis may depend on the efficient integration of photoactive semiconductors and catalysts to promote photoelectrochemical water splitting. Many efforts are currently devoted to the processing of multicomponent anodes, and cathodes, in the search for appropriate synergy between light absorbers and active catalysts. No single material appears to combine both features. Many experimental parameters are key to achieve the needed synergy between both systems, without clear protocols for success. Here we show how computational chemistry can shed some light into this cumbersome problem. DFT calculations are useful to predict adequate energy level alignment for thermodynamically favored hole transfer. As proof of concept, we experimentally confirmed the limited performance enhancement in hematite photoanodes decorated with the competent water oxidation catalyst cobalt hexacyanoferrate. Computational methods perfectly describe the misalignment of their energy levels, at the origin of this mismatch. Photoelectrochemical studies indicate that the catalyst exclusively acts as a hole-scavenger, shifting the hematite surface state to lower potentials. Although kinetics will still depend on interface architecture, our theoretical approach may identify and predict plausible semiconductor/catalyst combinations, speeding up the experimental work towards promising photoelectrocatalytic systems.
      PubDate: 2017-10-02T05:20:28.370252-05:
      DOI: 10.1002/cssc.201701538
       
  • Broadband-Emitting 2 D Hybrid Organic–Inorganic Perovskite Based on
           Cyclohexane-bis(methylamonium) Cation
    • Authors: Ishita Neogi; Annalisa Bruno, Damodaran Bahulayan, Teck Wee Goh, Biplab Ghosh, Rakesh Ganguly, Daniele Cortecchia, Tze Chien Sum, Cesare Soci, Nripan Mathews, Subodh Gautam Mhaisalkar
      Abstract: The Cover Feature shows the stereoisomeric structures of a white-light emitting layered hybrid perovskite based on the cis-1,3-bis(methylaminohydrobromide)cyclohexane core. Layered hybrid perovskites are of interest as they are solution-processable materials with potential for cost-effective lighting and displays. In addition, their broadband emission is related to the formation of intra-band color centers. The photoluminescence of the material presented here shows a strong dependence on the stereoisomerism of the core cation. More information can be found in the Full Paper by Neogi et al.
      PubDate: 2017-10-02T01:35:24.171353-05:
      DOI: 10.1002/cssc.201701763
       
  • Low-polarization lithium oxygen battery using
           N,N-diethyl-N-(2-methoxyethyl)-N-methylammonium
           bis(trifluoromethanesulphonyl) imide (DEMETFSI) ionic liquid electrolyte
    • Authors: Ulderico Ulissi; Giuseppe Antonio Elia, Sangsik Jeong, Franziska Mueller, Jakub Reiter, Nikolaos Tsiouvaras, Yang-Kook Sun, Bruno Scrosati, Stefano Passerini, Jusef Hassoun
      Abstract: The room temperature molten salt mixture of N,N-diethyl-N-(2-methoxyethyl)-N-methylammonium bis(trifluoromethanesulfonyl) imide (DEMETFSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt is herein reported as electrolyte for application in lithium oxygen batteries. The DEMETFSI-LITFSI solution is studied in terms of ionic conductivity, viscosity, electrochemical stability and compatibility with lithium metal at 30°C, 40°C and 60°C. The electrolyte shows suitable properties for application in lithium oxygen battery, allowing a reversible, low-polarization discharge-charge performance with a capacity of about 13 Ah per gram of carbon in the positive electrode and coulombic efficiency approaching 100%. The reversibility of the oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) is demonstrated by ex situ XRD and SEM studies. Furthermore, the study of the cycling behavior of the lithium oxygen cell using the DEMETFSI-LITFSI electrolyte at increasing temperatures (from 30°C to 60°C) evidences enhanced energy efficiency together with morphology changes of the deposit. In addition, the use of carbon-coated Zn0.9Fe0.1O (TMO-C) lithium-conversion anode in an IL-based Li-ion oxygen configuration is preliminarily demonstrated.
      PubDate: 2017-09-29T08:42:41.400739-05:
      DOI: 10.1002/cssc.201701696
       
  • Exploring the reaction pathways of bio-glycerol hydro-deoxygenation to
           propene over Molybdena-based catalysts
    • Authors: Vasiliki Zacharopoulou; Efterpi Vasiliadou, Angeliki A Lemonidou
      Abstract: One-step glycerol reaction with hydrogen, selectively forming propene, is a novel and particularly challenging catalytic pathway that has not yet been thoroughly explored in the open literature. Molybdena-based catalysts are active and selective to C-O bond scission; propene is the only product in the gas phase, under the standard reaction conditions, impeding further hydrogenation to propane. Within this context, this work focuses on exploration of the reaction pathways and the investigation of various parameters, affecting the catalytic performance, such as the role of hydrogen on the product distribution and the effect of the catalyst pretreatment step. Under hydrogen atmosphere, propene is primarily produced via 2-propenol formation, while under inert atmosphere propanal and glycerol dissociation products are mainly formed. Reaction most likely proceeds through a reverse Mars van Krevelen mechanism, as the partially reduced Mo species drive the reaction to the formation of the desired product.
      PubDate: 2017-09-28T10:30:44.058516-05:
      DOI: 10.1002/cssc.201701605
       
  • Solar Water Splitting Utilizing a Wide Range of Sunlight upon Combination
           with a SiC Photocathode, a BiVO4 Photoanode, and a Perovskite Solar Cell
    • Authors: Akihide Iwase; Akihiko Kudo, Youhei Numata, Masashi Ikegami, Tsutomu Miyasaka, Naoto Ichikawa, Masashi Kato, Hideki Hashimoto, Haruo Inoue, Osamu Ishitani, Hitoshi Tamiaki
      Abstract: We have successfully demonstrated solar water splitting using newly fabricated photoelectrochemical system with a Pt-loaded SiC photocathode, a CoOx-loaded BiVO4 photoanode, and a perovskite solar cell. Detection of the evolved H2 and O2 with 100% Faradaic efficiency indicates that the observed photocurrent was used for water splitting. The solar to hydrogen (STH) efficiency was 0.55% under no-additional bias conditions.
      PubDate: 2017-09-28T02:20:32.935812-05:
      DOI: 10.1002/cssc.201701663
       
  • Preface to Special Issue of ChemSusChem on Perovskite Optoelectronics
    • Authors: Henk J. Bolink; Subodh G. Mhaisalkar
      Abstract: This Editorial introduces one of two companion Special Issues on “Halide Perovskites for Optoelectronics Applications” in ChemSusChem and Energy Technology following the ICMAT 2017 Conference in Singapore. More information on the other Special Issue can be found in the Editorial published in Energy Technology.Optoelectronic arts: This Editorial introduces one of two companion Special Issues on “Halide Perovskites for Optoelectronics Applications” in ChemSusChem and Energy Technology following the ICMAT 2017 Conference in Singapore. More information on the companion Special Issue can be found in the Editorial published in Energy Technology.
      PubDate: 2017-09-26T09:20:49.431464-05:
      DOI: 10.1002/cssc.201701756
       
  • High Efficiency MAPbI3 Perovskite Solar Cell Using a Pure Thin Film of
           Polyoxometalate as Scaffold Layer
    • Authors: Mohammad Khaledi Sardashti; Mahmoud Zendehdel, Narges Yaghoobi Nia, Davud Karimian, Mohammad Sheikhi
      Abstract: The Cover Feature shows the pioneering use of a pure thin film of [SiW11O39]8− polyoxometalate (POM) structure as a scaffold layer for CH3NH3PbI3-based perovskite solar cells (PSCs). In their Full Paper, Sardashti et al. demonstrate high-efficiency PSCs fabricated using solution-based low-temperature deposition methods in ambient conditions. The smooth nanoporous structure of POM with high electron transport in the interlayer and the modified POM/perovskite interface result in high-performance PSCs with no hysteresis and low recombination. More information can be found in the Full Paper by Sardashti et al.
      PubDate: 2017-09-26T09:20:45.187842-05:
      DOI: 10.1002/cssc.201701764
       
  • Mesoporous Carbon Nanospheres Encapsulated Ultrasmall Ir Clusters as
           Highly Selective Nanocatalysts for (Bio-)Alcohols Methylation Using
           Methanol as Sustainable C1 Feedstock
    • Authors: Qiang Liu; Guoqiang Xu, Zhendong Wang, Xiaoran Liu, Xicheng Wang, Linlin Dong, Xindong Mu, Huizhou Liu
      Abstract: C-H methylation is an attractive chemical transformation for C-C bonds construction in organic chemistry, yet efficient methylation of readily available (bio-)alcohols in water using methanol as sustainable C1 feedstock is limited. Herein, yolk-shell-structured mesoporous carbon nanospheres encapsulated Ir nanocatalysts (Ir@YSMCNs) have been synthesized for this transformation. Monodispersed Ir clusters (ca. 1.0 nm) were in situ encapsulated and spatially isolated within YSMCNs by a silica-assisted sol-gel emulsion strategy. A selection of (bio-)alcohols (19 examples) was selectively methylated in aqueous phase with good-to-high yields over the developed Ir@YSMCNs. The improved catalytic efficiencies in terms of activity, selectivity together with the good stability and recyclability were contributable to the ultrasmall Ir clusters with oxidation chemical state as a consequence of the confinement effect of YSMCNs with interconnected nanostructures.
      PubDate: 2017-09-25T23:15:27.000918-05:
      DOI: 10.1002/cssc.201701607
       
  • Light-driven hydrogen evolution by nickel-substituted rubredoxin
    • Authors: Michael J. Stevenson; Sean C. Marguet, Camille R. Schneider, Hannah S. Shafaat
      Abstract: An enzymatic system for light-driven hydrogen generation has been developed through covalent attachment of a ruthenium chromophore to nickel-substituted rubredoxin (NiRd). The photoinduced activity of the hybrid enzyme is significantly greater than that of a two-component system and is strongly dependent on the position of the ruthenium phototrigger relative to the active site, indicating a role for intramolecular electron transfer in catalysis. Steady-state and time-resolved emission spectra reveal a pathway for rapid, direct quenching of the ruthenium excited state by nickel, though low overall turnover numbers suggest initial electron transfer is not the rate-limiting step. This approach is ideally suited for detailed mechanistic investigations of catalysis by NiRd and other molecular systems, with implications for generation of solar fuels.
      PubDate: 2017-09-25T21:20:34.471704-05:
      DOI: 10.1002/cssc.201701627
       
  • A bis-amide ruthenium polypyridyl complex as a robust and efficient
           photosensitizer for H2 production
    • Authors: Garry Shawn Hanan; Amlan K. Pal, Olivier Schott, Daniel Chartrand
      Abstract: A bis-amide polypyridyl ruthenium photosensitizer 1 reveals a large improvement in photocatalytic stability, rate of activity and efficiency in photocatalytic H2 production when compared to [Ru(bpy)3]2+. The photocatalytic system of 1 combined with a cobaltoxime was found to be highly efficient under blue-light (Turnover number (TON) = 7800) and green-light (TON = 7200) irradiation while [Ru(bpy)3]2+ was significantly less effective with a TON of 2600 and 1100, respectively. The greatest improvement was under red LED irradiation, with 1 and cobaltoxime exhibiting a TON of 4200 compared to [Ru(bpy)3]2+ and cobaltoxime at only 71.
      PubDate: 2017-09-25T15:15:43.622436-05:
      DOI: 10.1002/cssc.201701543
       
  • Factors Influencing the Mechanical Properties of Formamidinium Lead
           Halides and Related Hybrid Perovskites
    • Authors: Shijing Sun; Furkan H. Isikgor, Zeyu Deng, Fengxia Wei, Gregor Kieslich, Paul D. Bristowe, Jianyong Ouyang, Anthony K. Cheetham
      Abstract: The Cover Picture shows a graphical representation of the use of the nanoindentation technique to probe the intrinsic mechanical properties of hybrid perovskites. The dynamic nature of the lead-halide perovskite framework gives rise to mechanical flexibility, leading to relatively low Young's moduli and hardnesses. The structural–mechanical relationships were further explored by X-ray crystallography and density functional theory calculations, where the effect of structural anisotropy, the size of the A cations and hydrogen bonding on the material's response under uniaxial stress were addressed. More details can be found in the Communication by Sun et al. (
      DOI : 10.1002/cssc.201700991).
      PubDate: 2017-09-25T05:25:20.469587-05:
       
  • Non-aqueous Primary Li-air Flow Battery and Optimization of its Cathode
           through Experiments and Modeling
    • Authors: Byoungsu kim; Kensuke Takechi, Sichao Ma, Sumit Verma, Shiqi Fu, Amit Desai, Ashtamurthy S Pawate, Fuminori Mizuno, Paul Kenis
      Abstract: We develop a primary Li-air battery with a flowing Li-ion free ionic liquid as the recyclable electrolyte, boosting power capability due to promoted superoxide diffusion and enhancing discharge capacity due to separately stored discharge products. Also we use experimental and computational tools to analyze cathode properties leading to a set of parameters that improve the discharge current density of the non-aqueous Li-air flow battery. We systematically modified the structure and configuration of the cathode gas diffusion layers (GDLs) by using different levels of hot-pressing and the presence or absence of a microporous layer (MPL). These experiments revealed that use of thinner but denser MPLs are key for performance optimization; indeed, this led to an improvement in discharge current density. Also, computational results indicate that the extent of electrolyte immersion and porosity of the cathode can be optimized to achieve higher current density.
      PubDate: 2017-09-22T23:25:47.58321-05:0
      DOI: 10.1002/cssc.201701255
       
  • Discovery of open cubane-core Structures for biomimetic {LnCo3(OR)4} Water
           Oxidation Catalysts
    • Authors: Sandra Luber; Mauro Schilling, Florian Hodel
      Abstract: Bio-mimetic catalysts such as {LnCo3(OR)4} (Ln = Er, Tm, OR = alkoxide) cubanes have recently been in the focus of research for artificial water oxidation processes. Previously the remarkable adaptability with respect to ligand shell, nuclear structure as well as protonation and oxidation states of those catalysts has been shown to be beneficial for the water oxidation process. We further explored the structural flexibility of those catalysts and present here a series of novel structures in which one metal center is pulled out of the cubane cage. This leads to an open cubane core, which is to some extend reminiscent of observed open/closed cubane core forms of the oxygen-evolving complex in nature's photosystem II. We investigate how those open cubane core models alter the thermodynamics of the water oxidation cycle and how different solvation approaches influence their stability.
      PubDate: 2017-09-22T06:21:36.760282-05:
      DOI: 10.1002/cssc.201701527
       
  • Interface Manipulation Improving Plasmon-Coupled Photoelectrochemical
           Water Splitting on α-Fe2O3 Photoanodes
    • Authors: Zhe Xu; Zhongwen Fan, Zhan Shi, Mengyu Li, Jianyong Feng, Lang Pei, Chenguang Zhou, Junkang Zhou, Lingxia Yang, Wenchao Li, Guangzhou Xu, Shicheng Yan, Zhigang Zou
      Abstract: Plasmon resonance effect of metal nanoparticles (NPs) offers a promising route to improve the solar energy conversion efficiency of semiconductors. Here, we found that the hot electrons generated by plasmon resonance effect of Au NPs tend to inject into the surface states instead of the conduction band of Fe2O3 photoanodes, then the severe surface recombination occurs. Such an electron transfer process seems to be independent on external applied potentials, but is sensitive to metal-semiconductor interface properties. Passivating the surface states of Fe2O3 by a non-catalytic Al2O3 layer can construct an effective resonant energy transfer interface between Ti-doped Fe2O3 (Ti-Fe2O3) and Au NPs. In such a Ti-Fe2O3/Al2O3/Au electrode configuration, the enhanced photoelectrochemical water splitting performance can be attributed to the following two factors: (1) in non-light-response wavelength range of Au NPs, both relaxing Fermi pinning effect by Al2O3 passivation layer and higher work function of Au enlarged band bending, thus promoting the charge separation. (2) In light-response wavelength range of Au NPs, the effective resonant energy transfer contributes to the light harvesting and conversion. The interface manipulation proposed in our study may provide a new route to design efficient plasmonic PEC devices for energy conversion
      PubDate: 2017-09-21T21:20:51.705638-05:
      DOI: 10.1002/cssc.201701679
       
  • Preparation of Cobalt-Based Electrodes by Physical Vapor Deposition on
           Various Nonconductive Substrates for Electrocatalytic Water Oxidation
    • Authors: Yizhen Wu; Le Wang, Mingxing Chen, Zhaoxia Jin, Wei Zhang, Rui Cao
      Abstract: Artificial photosynthesis requires efficient anodic electrode materials for water oxidation. We herein report the facial preparation of Co metal thin films through physical vapor deposition (PVD) on various nonconductive substrates, including regular and quartz glass, mica sheet, polyimide, and polyethylene terephthalate (PET). Subsequent surface electrochemical modification using cyclic voltammetry (CV) makes these films active for electrocatalytic water oxidation by reaching a current density of 10 mA cm−2 at a low overpotential of 330 mV in 1.0 M KOH solution. These electrodes are robust with unchanged activity in prolonged chronopotentiometry measurements. This work is thus significant to show that the combination of PVD and CV is very valuable and convenient to fabricate active electrodes using various nonconductive substrates, particularly, flexible polyimide and PET substrates. This efficient, safe and convenient way can be potentially expanded to many other electrochemical applications.
      PubDate: 2017-09-21T09:20:43.228645-05:
      DOI: 10.1002/cssc.201701576
       
  • Graphene-Supported Pyrene-Modified Cobalt Corrole with Axial
           Triphenylphosphine for Enhanced Hydrogen Evolution in pH 0–14 Aqueous
           Solutions
    • Authors: Xialiang Li; Haitao Lei, Xiaojun Guo, Xueli Zhao, Shuping Ding, Xueqing Gao, Wei Zhang, Rui Cao
      Abstract: A cobalt complex of 5,15-bis(pentafluorophenyl)-10-(4)-(1-pyrenyl)phenyl corrole that contains a triphenylphosphine axial ligand (1-PPh3) was synthesized and examined as an electrocatalyst for the hydrogen evolution reaction (HER). If supported on graphene (G), the resulting 1-PPh3/G material can catalyze the HER in aqueous solutions over a wide pH range of 0–14 with a high efficiency and durability. The significantly enhanced activity of 1-PPh3/G, compared with that of its analogues 1-py/G (the Co-bound axial ligand is pyridine instead of triphenylphosphine) and 2-py/G (Co complex of 5,10,15-tris(pentafluorophenyl)corrole), highlights the effects of the pyrenyl substituent and the triphenylphosphine axial ligand on the HER activity. On one hand, the pyrenyl moiety can increase the π–π interactions between 1 and graphene and thus lead to a fast electron transfer from the electrode to 1. On the other hand, the triphenylphosphine axial ligand can increase the electron density (basicity) of Co and thus make the metal center more reactive to protons at the trans position through a so-called “push effect”. This study concerns a significant example that shows the trans effect of the axial ligand on the HER, which has been investigated rarely. The combination of various ligand-design strategies in one molecule has been realized in 1-PPh3 to achieve a high catalytic HER performance. These factors are valuable to be used in other molecular catalyst systems.In the company of corroles: Graphene-supported cobalt corroles are active and stable catalysts for the hydrogen evolution reaction in water over a wide pH range of 0–14. The introduction of a pyrenyl group to the corrole macrocycle and the use of a triphenylphosphine axial ligand on Co improve the catalytic efficiency significantly.
      PubDate: 2017-09-21T07:51:34.330007-05:
      DOI: 10.1002/cssc.201701196
       
  • Reactive electrophilic OI--species evidenced in high-performance
           Ir-oxohydroxide water oxidation electrocatalysts
    • Authors: Cyriac Massué; Verena Pfeifer, Maurice Van Gastel, Johannes Noack, Gerardo Algara-Siller, Sebastien Cap, Robert Schlögl
      Abstract: Although quasi-amorphous Ir-oxohydroxides haverepeatedly been identified as superior oxygen evolution reaction(OER) electrocatalysts, an exact description of the performance relevantspecies has so far remained a challenge. In this context, wereport on the characterization of hydrothermally prepared IrIII/IV oxohydroxides exhibiting exceptional OER-performance. It was foundthat holes in the O2p states of IrIII/IV-oxohydroxides result in reactiveOI--species identified by characteristic NEXAFS-features. Aprototypical titration reaction based on CO as a probe molecule showsthat these OI--species are highly susceptible to nucleophilic attack atroom temperature. Similarly to pre-activated oxygen involved in thebiological OER in Photosystem II, the electrophilic OI--speciesevidenced in IrIII/IV-oxohydroxides are suggested to be precursors tospecies involved in the O-O bond formation during electrocatalyticOER. CO-titration also highlights a link between OER-performanceand the surface/sub-surface mobility of OI--species. The superiorelectrocatalytic properties of IrIII/IV-oxohydroxides are thus explainedby their ability to accommodate pre-activated electrophilic OI--speciesable to migrate within the lattice.
      PubDate: 2017-09-21T03:21:02.885574-05:
      DOI: 10.1002/cssc.201701291
       
  • BiVO4 Fern Architectures: A Competitive Anode for Li-ion Batteries
    • Authors: Deepak Dubal; Deepak Patil, Santosh Patil, N. R. Munirathnam, Pedro Gomez-Romero
      Abstract: The search of high-performance anode materials for Lithium-ion batteries (LIBs) is currently one of the most important tasks. Herein, we are introducing BiVO4 fern architectures as a new anode material for LIBs. The BiVO4 fern shows an excellent reversible capacity of 769 mAh/g (ultrahigh volumetric capacity of 3984 mAh/cm3) at 0.12 A/g with a great capacity retention. Later, a LIB full cell is assembled with BiVO4 ferns as anode and LiFePO4 (LFP, commercial) as cathode material. Notably, the device can achieve the capacity of 140 mAh/g at 1C rate that is 81 % of the capacity of cathode and maintained to 104 mAh/g at high C-rate of 8C, which makes BiVO4 a promising candidate as high-energy anode materials for LIBs.
      PubDate: 2017-09-21T00:15:54.24716-05:0
      DOI: 10.1002/cssc.201701483
       
  • Imidazolium Ions with an Alcohol Substituent for Enhanced Electrocatalytic
           Reduction of CO2
    • Authors: Xianbo Jin; Lin Zhang, Nian Wu, Jichen Zhang, Yang Hu, Zhiyong Wang, Lin Zhuang
      Abstract: Electrochemical reduction of CO2 to CO is attractive for carbon dioxide reduction, energy regeneration and storage. Imidazolium Ionic liquids (IMILs) are promising electrolyte catalysts for this important reaction. Herein we report functionalizing the imidazolium ion with a propanol substituent at the N site can significantly enhance the catalytic activity of IMILs, causing a positive shift of the onset potential for the CO2 reduction by about 90 mV in an acetonitrile electrolyte. Theoretical calculation indicated that the propanol hydroxyl could bridge a local hydrogen bonding chain as shortcut for proton transfer, leading to a dramatic decrease of the activation barrier for the IMIL-catalytic reduction of CO2.
      PubDate: 2017-09-20T04:20:22.109872-05:
      DOI: 10.1002/cssc.201701673
       
  • Enhancing Photocurrent Generation in Photosynthetic Reaction Center-based
           Photoelectrochemical Cells with Biomimetic DNA Antenna
    • Authors: Anne-Marie Carey; Haojie Zhang, Minghui Liu, Daiana Sharaf, Natalie Akram, Hao Yan, Su Lin, Neal Woodbury, Dong-Kyun Seo
      Abstract: 3 to 4 times higher performance of biohybrid photoelectrochemical cells with photosynthetic reaction centers (RC) has been achieved by using a DNA-based biomimetic antenna. Synthetic dyes Cy3 and Cy5 were chosen and strategically placed in the anntena in such a way that they can collect additional light energy in the visible region of the solar spectrum and transfer it to RC through Förster resonance energy transfer (FRET). The antenna, a DNA templated multiple dye system, is attached to each Rhodobacter sphaeroides RC near the primary donor, P, to facilitate the energy transfer process. Excitation with a broad light spectrum (approximating sunlight) triggers a cascade of excitation energy transfer from Cy3 to Cy5 to P, and also directly from Cy5 to P. This additional excitation energy increases RC absorbance cross-section in the visible and thus, the performance of the photoelectrochemical cells. DNA-based biomimetic antennas offer a tunable, modular light-harvesting system for enhancing RC solar coverage and performance for photoelectrochemical cells.
      PubDate: 2017-09-19T20:51:03.01933-05:0
      DOI: 10.1002/cssc.201701390
       
  • NIR Absorbing Metal-Free Organic, Porphyrin, and Phthalocyanine Dyes for
           Panchromatic DSCs
    • Authors: Phillip Brogdon; Hammad Cheema, Jared Heath Delcamp
      Abstract: Dye-sensitized solar cells (DSCs) are a promising source of renewable energy. However, power conversion efficiency (PCE) of devices has been limited largely by the difficulty of producing electricity using photons from the near-infrared (NIR) spectral region. Metal-free organic sensitizers frequently employ strong electron donating or withdrawing moieties to tune the optical band gap to allow the absorption of lower energy wavelengths in charge transfer systems while porphyrins and phthalocyanines use substituents to shift the Soret and Q bands toward lower energy absorption. Very few devices employing precious metal free dyes have been able to achieve panchromatic, NIR photon conversion for electricity generation at wavelengths>750 nm despite a tremendous number of sensitizers published over last 25 years. This minireview seeks to compile a summary of these sensitizers to encourage assimilation, analysis and development of efficient future NIR sensitizers. Herein, we discuss common synthetic strategies, optical properties and electronic properties of the most successful panchromatic organic sensitizers in this regard.
      PubDate: 2017-09-19T13:40:32.723807-05:
      DOI: 10.1002/cssc.201701441
       
  • A Strategy for Simultaneous Synthesis of Methallyl Alcohol and Diethyl
           Acetal with Sn-β
    • Authors: Wenda Hu; Yan Wan, Lili Zhu, Xiaojie Cheng, Shaolong Wan, Jingdong Lin, Yong Wang
      Abstract: Herein we report a strategy to simultaneously produce two important chemicals namely Methallyl alcohol (Mol) and diethyl acetal (Dal) from methacrolein (Mal) in ethanol solvent at low temperature with the use of Beta zeolites modified by tin (Sn-β catalysts). All Sn-β catalysts were prepared by the solid-state ion-exchange (SSIE) method, wherein the calcination step was conducted in different gas atmospheres. The one pre-calcined in Ar (Sn-β-Ar) diminishes the number of extra-framework Sn species and instead enables more Sn species exchanged into the framework as isolated tetrahedral Sn (IV), thus enhancing the catalytic activity of Meerwein-Ponndorf-Verley (MPV) reaction. The sodium-exchanged Sn-β-Ar, with the weak Brønsted acid site further diminished, leads to an even better result to Mol, thanks to the restriction of those side reactions such as acetalization, addition and etherification. Under optimized catalyst and reaction condition, the yield of Mol and Dal could reach about 90% and 96%, respectively. The possible reaction pathway, along with the complex network of side products, was proposed after a detailed investigation through the use of different substrates as the reactants. The findings of Sn-β fine-tuned through different treatment in this work, are of great significance toward understanding and manipulating the complex reaction between ɑ, β-unsaturated aldehydes and primary alcohols.
      PubDate: 2017-09-19T07:40:44.303221-05:
      DOI: 10.1002/cssc.201701435
       
  • Ring-Opening Polymerization of L-Lactide to Cyclic Poly(Lactide) by
           Zeolitic Imidazole Framework-8 Catalyst
    • Authors: Zhixiong Luo; Somboon Chaemchuen, Kui Zhou, Francis Verpoort
      Abstract: The catalytic activity of ZIF-8 in the ring-opening polymerization of L-lactide without solvents or co-catalysts is presented for the first time. Two different synthetic strategies have been applied for synthesizing ZIF-8, either under solvothermal condition or by spray-drying procedure. Their catalytic activities are found to be correlating with the presence of open active sites in ZIF-8 structure. The structural defects which afford active acid and basic sites are supposed to cooperatively catalyze the reaction. ZIF-8 assembled by spray-drying technique, displays a superior catalytic activity at temperature of 160 °C, leading to the formation of high molecular weight cyclic polylactide. The ZIF-8 catalysts could be recycled and reused without any significant loss of catalytic activity.
      PubDate: 2017-09-18T21:45:33.605983-05:
      DOI: 10.1002/cssc.201701438
       
  • Catalyst stability benchmarking for the oxygen evolution reaction - the
           importance of backing electrode material and dissolution in accelerated
           aging studies
    • Authors: Simon Geiger; Olga Kasian, Andrea M. Mingers, Shannon S. Nicley, Ken Haenen, Karl J. J. Mayrhofer, Serhiy Cherevko
      Abstract: In searching for alternative oxygen evolution reaction (OER) catalysts for acidic water splitting, fast screening of materials intrinsic activity and stability in half-cell tests is of vital importance. It significantly accelerates the discovery of new promising materials without the need of time-consuming real cell analysis. In commonly employed tests, a conclusion on the catalyst stability is drawn solely on the basis of pure electrochemical information, e.g. by evaluating potential vs. time profiles. In this work we demonstrate important limitations of such approaches, which are related to the degradation of the backing electrode material. For this purpose we use state-of-the-art Ir-black powder and investigate its OER activity and dissolution as a function of the backing electrode material. We show that even at very short time intervals materials like glassy carbon passivate, increasing the contact resistance and concealing the degradation phenomena of the electrocatalyst itself. Alternative backing electrodes like gold and boron doped diamond show a better stability and are thus recommended for short accelerated aging investigations. Moreover, parallel quantification of dissolution products in the electrolyte is shown to be of great importance for a solid comparison of OER catalyst feasibility.
      PubDate: 2017-09-18T11:45:25.259895-05:
      DOI: 10.1002/cssc.201701523
       
  • Anion Exchange Membranes for Alkaline Fuel Cell Applications: The Effects
           of Cations
    • Authors: Zhe Sun; Bencai Lin, Feng Yan
      Abstract: Alkaline anion exchange membrane fuel cells (AEMFCs) are attracting great attention, because of their potential use of non-precious electrocatalysts. Anion exchange membrane (AEM) is one of the key components of AEMFCs. An ideal AEM should possess high hydroxide conductivity and sufficient long-term durability at elevated temperatures in high pH solutions. This review provides recent progresses of alkaline stability behavior of cations (including quaternary ammonium, imidazolium, guanidinium, pyridinium, tertiary sulfonium, phosphonium, benzimidazolium and pyrrolidinium) and their analogous AEMs, which have been investigated by both experimental studies and theoretical calculations. Effects, including conjugated effect, steric hindrance effect, σ−π hyperconjugative effect and electron effect on the alkaline stability of cations and their analogous AEMs have been discussed. The attempt of this article is to give an overview of some key factors, for future design of novel cations, and their analogous AEMs with high alkaline stability.
      PubDate: 2017-09-18T10:40:40.577073-05:
      DOI: 10.1002/cssc.201701600
       
  • Mechanistic parameters of electrocatalytic water oxidation on LiMn2O4 in
           comparison to natural photosynthesis
    • Authors: Lennart Köhler; Majid Ebrahimizadeh Abrishami, Vladimir Roddatis, Janis Geppert, Marcel Risch
      Abstract: Targeted improvement of the low efficiency of water oxidation during the oxygen evolution reaction (OER) is severely hindered by insufficient knowledge of the electrocatalytic mechanism on heterogeneous surfaces. We chose LiMn2O4 as a model system for mechanistic investigations as it shares the cubane structure with the active site of photosystem II and the valence of Mn3.5+ with the dark-stable S1 state in the mechanism of natural photosynthesis. The investigated LiMn2O4 nanoparticles are electrochemically stable in NaOH electrolytes and show respectable activity in any of the main metrics. At low overpotential, the key mechanistic parameters of Tafel slope, Nernst slope and reaction order have constant values of 62(1) mV dec-1, 1(1) mV pH-1 (RHE), -0.04(2) (RHE), respectively. These values are interpreted in the context of the well-studied mechanism of natural photosynthesis. The uncovered difference in the reaction sequence is important for the design of efficient bio-inspired electrocatalysts.
      PubDate: 2017-09-18T05:40:49.544189-05:
      DOI: 10.1002/cssc.201701582
       
  • Enhanced formation of>C1 products in the electroreduction of CO2 by adding
           a carbon dioxide adsorption component to a gas diffusion layer-type
           catalytic electrode
    • Authors: Bhanu Chandra Marepally; Claudio Ampelli, Chiara Genovese, Tapish Saboo, Siglinda Perathoner, Florian M. Wisser, Laurent Veyre, Jérôme Canivet, Elsje Alessandra Quadrelli, Gabriele Centi
      Abstract: The addition of a CO2 adsorption component (substituted imidazolate-based SIM-1 crystals) to a gas diffusion layer (GDL) type catalytic electrode allows to enhance the activity and especially the selectivity to>C1 carbon chain products (ethanol, acetone and isopropanol) of a Pt-based electrocatalyst that is not able to form products of CO2 reduction involving C-C bond formation under conventional (liquid-phase) conditions. This indicates that the increase of the CO2 effective concentration at the electrode active surface is the factor controlling the formation of>C1 products rather than only the intrinsic properties of the electrocatalyst.
      PubDate: 2017-09-18T03:41:36.923837-05:
      DOI: 10.1002/cssc.201701506
       
  • Polaronic charge carrier - lattice interaction in lead halide perovskites
    • Authors: Christoph Wolf; Young-Hoon Kim, Himchan Cho, Tae-Woo Lee
      Abstract: Almost ten years after the renaissance of the popular perovskite-type semiconductors based on lead-salts with general formula AMX3 (A=organic or inorganic cation, M=divalent metal, X=halide), many facets of photophysics continue to puzzle researchers. In this review, we shed some light on the low mobilities of charge carriers in lead-halide perovskites with special focus on the lattice properties at non-zero temperature. The polar and soft lattice leads to pronounced electron-phonon coupling, limiting carrier mobility and retarding recombination. We propose that the proper picture of excited charge carriers at temperature ranges that are relevant for device operations is that of a polaron, with Fröhlich coupling constants between 1
      PubDate: 2017-09-18T00:15:21.889289-05:
      DOI: 10.1002/cssc.201701284
       
  • Natural and Artificial Mn4Ca-cluster for Water-Splitting Reaction
    • Authors: Chunxi Zhang; Changhui Chen, Yanxi Li, Guoqing Zhao, Ruoqing Yao
      Abstract: The oxygen-evolving center (OEC) in photosystem II (PSII) is a unique biological catalyst that splits water into electrons, protons and O2 by using solar energy. Recent crystallographic studies have revealed that the structure of the OEC is an asymmetric Mn4Ca-cluster, which provides a blueprint to develop man-made water-splitting catalysts in artificial photosynthesis. Although it is a great challenge to mimic the whole structure and function of the OEC in the laboratory, significant advances have recently been achieved. Recent progress on mimicking of the natural OEC is now reviewed and discussed. New strategies are suggested to construct more stable and efficient new generation of catalytic materials for the water-splitting reaction based on the artificial Mn4Ca-cluster in the future.
      PubDate: 2017-09-17T21:31:04.71808-05:0
      DOI: 10.1002/cssc.201701371
       
  • Stupendous Role of Co-sensitizers in Dye Sensitized Solar Cells
    • Authors: Lingamallu Giribabu; Vamsi Krishna Narra, Venkata Suman Krishna Jonnadula, Mrinalini Madoori, Prasanthkumar Seelam
      Abstract: Co-sensitization in dye sensitized solar cells (DSSCs) received significant attention for improving the efficiency and stability of renewable energy resources. In this context, ruthenium metal and porphyrin dyes based DSSCs achieved increment in power conversion efficiency (PCE) from 8 - 11% to 11-14% after addition of additives, co-adsorbents and co-sensitizers by reducing the aggregation and charge recombination. Among the three supporting materials, co-sensitizers played major role to enhance the performance and stability of DSSCs which assist in commercialization. In this review, we highlighted the importance of co-sensitizers in photovoltaic performance of ruthenium metal and porphyrin dye based solar cells. Consequently, co-sensitizers are rather important to modulate the PCE of DSSCs and find realistic future practical applications.
      PubDate: 2017-09-16T04:20:22.917607-05:
      DOI: 10.1002/cssc.201701224
       
  • Chemoselective and catalyst-free O-borylation of silanols: a facile access
           to borasiloxanes
    • Authors: Krzysztof Kuciński; Grzegorz Hreczycho
      Abstract: This paper demonstrates, for the first time, a highly chemoselective synthesis of various borasiloxanes from hydroboranes and silanols which was achieved through a catalyst-free dehydrogenative coupling at room temperature. This green protocol, which uses easily accessible reagents, allows for the obtaining of borasiloxanes under air atmosphere and solvent-free conditions.
      PubDate: 2017-09-15T12:21:01.830659-05:
      DOI: 10.1002/cssc.201701648
       
  • Fuel Production from Seawater and Fuel Cells Using Seawater
    • Authors: Shunichi Fukuzumi; Yong-Min Lee, Wonwoo Nam
      Abstract: Seawater is the most abundant resource on our planet and fuel production from seawater has the remarkable merit that it would not compete with growing demands of pure water. This review focuses on the production of fuels from seawater and their direct use in fuel cells. Electrolysis of seawater under appropriate conditions affords hydrogen and dioxygen with 100% Faradaic efficiency without oxidation of chloride ion. Photoelectrocatalytic production of hydrogen from seawater provides promising way to produce hydrogen with low cost and high efficiency. Microbial solar cells (MSCs) using biofilms produced in seawater can generate electricity from sun light without additional fuel because the products of photosynthesis can be utilized as electrode reactants, while the electrode products can be utilized as photosynthetic reactants. Another important source for hydrogen is hydrogen sulfide, which is abundantly found in Black Sea deep water. Hydrogen is produced by electrolysis of Black Sea deep water that can also be used in hydrogen fuel cells. Production of a fuel and its direct use in a fuel cell has been made possible for the first time by combination of photocatalytic production of hydrogen peroxide from seawater and dioxygen in the air and its direct use in one-compartment hydrogen peroxide fuel cells to obtain electric power.
      PubDate: 2017-09-15T04:20:27.485191-05:
      DOI: 10.1002/cssc.201701381
       
  • Application of Pulse Radiolysis to Mechanistic Investigations of Catalysis
           Relevant to Artificial Photosynthesis
    • Authors: Etsuko Fujita; David C Grills, Dmitry E Polyansky
      Abstract: Taking inspiration from natural photosystems, the goal of artificial photosynthesis is to harness solar energy to convert abundant materials, such as CO2 and H2O, into solar fuels. Catalysts are required to ensure that the necessary redox half-reactions proceed in the most energy-efficient manner. It is therefore critical to gain a detailed mechanistic understanding of these catalytic reactions in order to develop new and improved catalysts. Many of the key catalytic intermediates are short-lived transient species, requiring time-resolved spectroscopic techniques for their observation. The two main methods for rapidly generating such species on the sub-microsecond timescale are laser flash photolysis and pulse radiolysis. These methods complement one another, and both can provide important spectroscopic and kinetic information. However, pulse radiolysis proves to be superior in systems with significant spectroscopic overlap between photosensitizer and other species present during the reaction. Here, we review the pulse radiolysis technique and how it has been applied to mechanistic investigations of half-reactions relevant to artificial photosynthesis.
      PubDate: 2017-09-12T15:15:25.440615-05:
      DOI: 10.1002/cssc.201701559
       
  • Green and sustainable route to carbohydrate vinyl ethers for accessing
           bio-inspired materials with a unique microspherical morphology
    • Authors: Konstantin Rodygin; Irina Werner, Valentine P. Ananikov
      Abstract: Synthesizing chemicals and materials based on renewable sources is one of the main tasks of modern science. Carbohydrates represent excellent renewable natural raw materials, that are eco-friendly, inexpensive and biologically compatible. Herein, we developed a green vinylation procedure for carbohydrates using readily available calcium carbide. Various carbohydrates were utilized as starting materials resulting in mono-, di- and tetra-vinyl ethers in high to excellent yields (81-92 %). The synthesized bio-based vinyl ethers were utilized as monomers in free radical and cationic polymerizations. A unique combination of smooth surface and intrinsic microcompartments was achieved in the synthesized materials. Two types of bio-based materials were prepared involving microspheres and "Swiss cheese" polymers. Scanning electron microscopy with built-in ion beam cutting was applied to reveal the spatial hierarchical structures in three-dimensional space.
      PubDate: 2017-09-12T05:21:44.227869-05:
      DOI: 10.1002/cssc.201701489
       
  • Rational Development of Neutral Aqueous Electrolytes for Zinc-Air
           Batteries
    • Authors: Simon Clark; Arnulf Latz, Birger Horstmann
      Abstract: Neutral aqueous electrolytes have been shown to extend both the calendar-life and cycling stability of secondary zinc-air batteries (ZABs). Despite this promise, there are currently no modeling studies investigating the performance of neutral ZABs. Traditional continuum models are numerically insufficient to simulate the dynamic behavior of these complex systems, due to the rapid, orders-of-magnitude concentration shifts that occur. In this work, we present a novel framework for modeling the cell-level performance of pH-buffered aqueous electrolytes. We apply our model to conduct the first continuum-scale simulation of secondary ZABs with aqueous ZnCl2-NH4Cl electrolytes. We first use our model to interpret the results of two recent experimental studies of neutral ZABs, and show that the stability of the pH is a significant factor in cell performance. We then optimize the composition of the electrolyte and the design of the cell considering factors including pH stability, final discharge product and overall energy density. Our simulations predict that the effectiveness of the pH buffer is limited by slow mass transport and that chlorine-containing solids may precipitate in addition to ZnO.
      PubDate: 2017-09-12T05:21:19.927613-05:
      DOI: 10.1002/cssc.201701468
       
  • Enhanced Trace CO2 Capture on Heteroatom-substituted RHO zeolites under
           Humid Conditions
    • Authors: Quan-li Ke; Tian-jun Sun, Xiao-li Wei, Ya Guo, Shu-Dong Wang
      Abstract: In this paper, boron and copper heteroatoms were successfully incorporated into the frameworks of high-silica RHO zeolite by adopting a bulky alkali metal-crown ether (AMCE) complex as the template. As a consequence, these heteroatom-doped zeolites show both larger micropore surface areas and volumes than those of their aluminosilicate analogue. Proton-type RHO zeolites were then applied for separation of CO2 / CH4 / N2 mixtures so as to weaken the electric field of these zeolites and then decrease the adsorption heat. The adsorption results show that a balance between working capacity and adsorption heat could be achieved harmoniously on these heteroatom-doped zeolites. The ideal adsorbed solution theory (IAST) predictions further demonstrate their high selectivities even for remarkably dilute sources of carbon dioxide. Finally, the heteroatom-substituted zeolites, especially the boron-substituted one, could be thermally regenerated rapidly at 150℃ after full hydration and could maintain high regenerability up to 30 cycles, which makes them potential candidates for trace CO2 removal under humid conditions.
      PubDate: 2017-09-12T04:20:31.025185-05:
      DOI: 10.1002/cssc.201701162
       
  • Catalytic upgrading of ethanol to n-butanol: A progress in catalyst
           development
    • Authors: Xianyuan Wu; Geqian Fang, Yuqin Tong, Dahao Jiang, Zhe Liang, Wenhua Leng, Liu Liu, Pengxiang Tu, Hongjing Wang, Jun Ni, Xiaonian Li
      Abstract: In view that n-butanol as fuel additive has more advantageous physico-chemical properties compared to ethanol, ethanol valorization to n-butanol via homogeneous or heterogeneous catalysis has received great attention over the last decades both in the scientific and industrial fields. This paper reviewed the recent progress in catalyst development for upgrading ethanol to n-butanol, which involves homogeneous catalysts such as Iridium and Ruthenium complexes catalysts and heterogeneous catalysts mainly including metal oxides, hydroxyapatite (HAP) and especially supported metal catalysts. The structure-performance relationship of catalysts and underlying reaction mechanism were critically examined. Future research directions on the catalyst design and improvement were also proposed.
      PubDate: 2017-09-12T03:21:19.653865-05:
      DOI: 10.1002/cssc.201701590
       
  • Single-Atom Catalysts of Precious Metals for Electrochemical Reactions
    • Authors: Jiwhan Kim; Hee-Eun Kim, Hyunjoo Lee
      Abstract: Single-atom catalysts (SACs), where the metal atom is dispersed on the support without forming nanoparticles, have been used for various heterogeneous reactions and most recently for electro-chemical reactions. In this mini-review, we introduce recent exam-ples of single-atom electrocatalysts used for the oxygen reduction reaction (ORR), hydrogen oxidation reaction (HOR), hydrogen evo-lution reaction (HER), formic acid oxidation reaction (FAOR), and methanol oxidation reaction (MOR). Many density functional theory (DFT) simulations have predicted that SACs may be effective for CO2 reduction towards methane or methanol production while sup-pressing H2 evolution, and those cases are introduced here as well. Single atoms, mainly Pt single atoms, have been deposited on TiN or TiC nanoparticles, defective graphene nanosheets, N-doped covalent triazine framework, graphitic carbon nitride, S-doped zeo-lite template carbon, and Sb-doped SnO2 surfaces. Scanning transmission electron microscopy, extended X-ray absorption fine structure measurement, and in-situ infrared spectroscopy have been used to detect the single-atom structure and confirm the ab-sence of nanoparticles. SACs have shown high mass activity, min-imizing the use of precious metal, and unique selectivity distinct from nanoparticle catalysts due to the absence of ensemble sites. Additional features that SACs should possess for effective elec-trochemical applications were also suggested.
      PubDate: 2017-09-11T22:21:26.837017-05:
      DOI: 10.1002/cssc.201701306
       
  • Decoupling the Effects of High Crystallinity and Surface Area on the
           Photocatalytic Overall Water Splitting over β-Ga2O3 Nanoparticles by
           Chemical Vapor Synthesis
    • Authors: Sasa Lukic; Jasper Menze, Philipp Weide, Wilma Busser, Markus Winterer, Martin Muhler
      Abstract: Chemical vapor synthesis (CVS) is a unique method to prepare well-defined photocatalyst materials with both large specific surface area and a high degree of crystallinity. The obtained β-Ga2O3 nanoparticles were optimized for photocatalysis by reductive photodeposition of the Rh/CrOx cocatalyst system. The influence of the degree of crystallinity and the specific surface area on photocatalytic aqueous methanol reforming and overall water splitting (OWS) was investigated by synthesizing β-Ga2O3 samples in the temperature range from 1000˚C to 1500˚C. With increasing temperature, the specific surface area and the microstrain were found to decrease, whereas the degree of crystallinity and the crystallite size increased. While the photocatalyst with the highest specific surface area showed the highest aqueous methanol reforming activity, the highest OWS activity was observed for the sample with an optimum ratio between high degree of crystallinity and specific surface area. Thus, it was possible to show that the facile aqueous methanol reforming and the demanding OWS have different requirements for high photocatalytic activity.
      PubDate: 2017-09-11T10:45:30.589035-05:
      DOI: 10.1002/cssc.201701309
       
  • In-Situ Formed Hierarchical Metal-Organic Flexible Cathode for High-Energy
           Sodium-Ion Batteries
    • Authors: Ying Huang; Chun Fang, Rui Zeng, Yaojun Liu, Wang Zhang, Yanjie Wang, Qingju Liu, Yunhui Huang
      Abstract: Metal-organic compounds are a family of electrode materials with structural diversity and excellent thermal stability for rechargeable batteries. Here, we fabricate a hierarchical nanocomposite with metal-organic cuprous tetracyanoquino- dimethane (CuTCNQ) in three-dimensional (3D) conductive carbon nanofibers (CNFs) network by in-situ growth, and evaluate it as flexible cathode for sodium-ion batteries (SIBs). CuTCNQ in such flexible composite electrode is able to exhibit a superhigh capacity of 252 mAh g-1 at 0.1 C and highly reversible stability for 1200 cycles within the voltage range of 2.5 - 4.1 V (vs. Na+/Na). A high specific energy of 762 Wh kg-1 is obtained with high average potential of 3.2 V (vs. Na+/Na). The in-situ formed electroactive metal-organic composites with tailored nanoarchitecture provide a promising alternative choice for high-performance cathode materials in sodium-ion batteries with high energy.
      PubDate: 2017-09-10T21:25:46.040595-05:
      DOI: 10.1002/cssc.201701484
       
  • Atom Transfer Radical Addition to Unactivated Alkenes Employing
           Heterogeneous Visible Light Photocatalysis
    • Authors: Liang-Liang Mao; Huan Cong
      Abstract: Heterogeneous visible light photocatalysis represents an important direction toward the development of sustainable organic synthesis. In this Communication, we report visible light-induced, heavy metal-free atom transfer radical addition to unactivated terminal olefins using the combination of heterogeneous titanium dioxide as photocatalyst and a hypervalent iodine(III) reagent as co-initiator. The reaction can be applied to a range of substrates with good functional group tolerance under very mild condition. In addition to a number of commonly used atom transfer reagents, the relatively challenging chloroform is also suitable.
      PubDate: 2017-09-09T00:35:24.207771-05:
      DOI: 10.1002/cssc.201701382
       
  • Homogeneous water oxidation by half-sandwich iridium(III)NHC complexes
           with pendant hydroxy and amino groups
    • Authors: Bani Mahanti; Greco González Miera, Elisa Martínez-Castro, Michele Bedin, Belén Martín-Matute, Sascha Ott, Anders Thapper
      Abstract: Herein we report three Ir(III)Cp* complexes with hydroxy- (1, 2) or amino- (3) functionalized N-heterocyclic carbene (NHC) ligands as catalysts for efficient water oxidation induced by addition of ceric ammonium nitrate (CAN). The pendant hydroxy- or amino- groups are very important for activity and the complexes with heteroatom-functionalized NHC ligands show up to 15 times higher rate of oxygen evolution in CAN-induced water oxidation compared to a reference Ir(III)Cp* complex without heteroatom functionalization (4). The presence of molecular high-valent Ir intermediates that are presumably involved in the rate-determining step for water oxidation is established by UV-vis spectroscopic and ESI mass spectrometric analyses during turnover conditions. The hydroxy-groups on the NHC ligands, as well as chloride ligands on the iridium center are proposed to structurally stabilize the high-valent species, and thereby improve the catalytic activity. The Ir(III) complex 1 with a hydroxy-functionalized NHC shows the highest catalytic activity with a TON of 2500 obtained in 3 h and with>90% yield relative to the amount of used oxidant.
      PubDate: 2017-09-08T07:41:07.108966-05:
      DOI: 10.1002/cssc.201701370
       
  • Effects of Self-Assembling Monolayer Modification of NiOx Nanoparticles
           Layer on the Performance of Inverted Perovskite Solar Cells and
           Application in High Power-Per-Weight Devices
    • Authors: Qin Wang; Chu-Chen Chueh, Ting Zhao, Morteza Eslamian, Wallace C.H. Choy, Alex K.-Y. Jen
      Abstract: Entirely low-temperature solution-processed (≤ 100 °C) planar p-i-n perovskite solar cells (PVSCs) offer great potential for commercialization of roll-to-roll fabricated photovoltaic devices. However, the stable inorganic hole transporting layer (HTL) in PVSCs is usually processed at high temperature (200 °C ~500 °C) which is far beyond the tolerant temperature (≤ 150 °C) of roll-to-roll fabrication. In this context, inorganic NiOx -nanoparticles (NPs) are an excellent candidate to serve as the HTL in PVSCs, owing to their excellent solution-processability at room temperature. However, the low-temperature processing condition is usually accompanied with defect formation.To suppress this setback, we used a series of benzoic acid self-assembly monolayers (SAMs) to passivate the surface defects of the NiOx NPs, and found that 4-bromobenzoic acid could effectively play the role of the surface passivation. This SAM layer reduces the trap-assisted recombination, minimizes the energy offset between the NiOx NPs and perovskite, and changes the HTL surface wettability, thus enhances the perovskite crystallization, resulting in more stable PVSCs with enhanced power conversion efficiency (PCE) of 18.4%, exceeding the control device PCE (15.5%). Also, we incorporated the above-mentioned SAMs into flexible PVSCs (F-PVSCs) and achieved one of the highest PCE of 16.2% on polyethylene terephthalate (PET) substrate with a remarkable power-per-weight of 26.9 W/g.
      PubDate: 2017-09-07T13:20:49.326827-05:
      DOI: 10.1002/cssc.201701262
       
  • Rational Design of Sulfur-Doped Copper Catalysts for the Selective
           Electroreduction of Carbon Dioxide to Formate
    • Authors: Yun Huang; Yilin Deng, Albertus Denny Handoko, Gregory K L Goh, Boon Siang Yeo
      Abstract: The selective electroreduction of CO2 to formate (or formic acid) is currently of great interest in the field of renewable energy utilization. In this work, we designed a sulfur-doped Cu2O-derived Cu catalyst, and showed that the presence of sulfur could significantly tune the selectivity of Cu from producing a myriad of CO2 reduction products to almost exclusively formate. Sulfur is doped into the Cu catalysts by dipping the Cu substrates into ammonium polysulfide solutions. Catalyst films with the highest sulfur content of 2.7 atom% showed the largest formate current density (jHCOO-) of -13.9 mA/cm2 at -0.9 V vs. RHE, which is ~46 times larger than that previously reported on Cu(110) surfaces. At -0.8 V vs. RHE, the Faradaic efficiency of formate was maintained at ~75% for 12 h of continuous electrolysis. By analyzing how the jHCOO- and jH2 of the catalysts evolved with different sulfur content, we show that sulfur doping efficaciously increases formate production, while suppressing the hydrogen evolution reaction. Ag-S and Cu-Se catalysts did not exhibit any significant enhancement towards the reduction of CO2 to formate. This demonstrates clearly that sulfur and copper acted synergistically to promote the selective formation of formate. A hypothesis of the role of sulfur is proposed and discussed.
      PubDate: 2017-09-07T09:21:31.786827-05:
      DOI: 10.1002/cssc.201701314
       
  • Anatase-TiO2 as low-cost and sustainable buffering filler for nanosize
           Silicon anodes in Lithium-ion batteries
    • Authors: Fabio Maroni; Gilberto Carbonari, Fausto Croce, Roberto Tossici, Francesco Nobili
      Abstract: The design of effective supporting matrices to efficiently cycle Si nanoparticles is often difficult to be achieved and requires complex preparation strategies. In this work, we present a simple synthesis of low-cost and environmentally benign Anatase-TiO2 nanoparticles as buffering filler for Si nanoparticles (Si@TiO2). Average anatase crystallite size is estimated in 5 nm. A complete structural, morphological and electrochemical characterization is performed. Electrochemical test results show very good specific capacity values around up to 1000 mAhg-1 and cycling at several specific currents, ranging from 500 mAg-1 to 2000 mAg-1, demonstrating a very good tolerance to high cycling rates. Post-mortem morphological analysis shows very good electrode integrity after 100 cycles at 500 mAg-1 specific current.
      PubDate: 2017-09-07T08:20:45.708226-05:
      DOI: 10.1002/cssc.201701431
       
  • Ultrathin composite polymeric membranes for CO2/N2 separation with minimum
           thickness and high CO2 permeance
    • Authors: Benito Javier; Javier Sánchez Laínez, Beatriz Zornoza, Santiago Martín, Mariolino Carta, Richard Malpass-Evans, Carlos Téllez, Neil B. McKeown, Joaquín Coronas, Ignacio Gascon
      Abstract: The use of ultrathin films as selective layers in composite membranes offers significant advantages in gas separation for increasing productivity whilst reducing the membrane size and energy costs. In this contribution, composite membranes have been obtained by the successive deposition of ca. 1 nm thick monolayers of a polymer of intrinsic microporosity (PIM) on top of dense membranes of the ultra-permeable poly[1-(trimethylsilyl)-1-propyne] (PTMSP). The ultrathin PIM films (30 nm in thickness) demonstrate CO2 permeance up to 7 times higher than dense PIM membranes using only 0.04% of the mass of PIM without a significant decrease in CO2/N2 selectivity.
      PubDate: 2017-09-06T11:34:16.009573-05:
      DOI: 10.1002/cssc.201701139
       
  • Optimization of Photoanodes for Photocatalytic Water Oxidation by
           Combining a Heterogenized Iridium Water-Oxidation Catalyst with a
           High-Potential Porphyrin Photosensitizer
    • Authors: Kelly L. Materna; Jianbing Jiang, Kevin P. Regan, Charles A. Schmuttenmaer, Robert H. Crabtree, Gary Brudvig
      Abstract: Development of water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) has gained interest due to their ability to generate renewable fuels using solar energy. In this study, photoanodes were assembled composed of a SnO2 film sensitized with a combination of a high potentialCF3-substituted porphyrin dye with a THP-protectedhydroxamic acid surface-anchoring group, and a Cp*-iridium water-oxidation catalystcontaining a silatrane anchoring group. The dye-to-catalyst ratios were varied from 2:1 to 32:1 to optimize photocatalytic water oxidation. Photoelectrochemical measurements not only showed more stable and reproducible photocurrents for lower dye-to-catalyst ratios, but photostability was also improved. O2 production was confirmed in real-time over a 20-hour period using a Clark electrode. Photoanodes prepared from 2:1 and 8:1 dye-to-catalyst sensitization solutions provided the most active electrodes for photocatalytic water oxidation, performing approximately 30-35 turnovers in 20 hours.
      PubDate: 2017-09-06T09:52:21.350035-05:
      DOI: 10.1002/cssc.201701693
       
  • Quantum Chemical Modeling of Homogeneous Water Oxidation Catalysis
    • Authors: Rong-Zhen Liao; Per Siegbahn
      Abstract: The design of efficient and robust water oxidation catalysts has proven challenging in the development of artificial photosynthetic systems for solar energy harnessing and storage. Tremendous progress has been made in the development of homogeneous transition metal complexes capable of mediating water oxidation. To improve the efficiency of the catalyst and to design new catalysts, a detailed mechanistic understanding is necessary. Quantum chemical model calculations have been successfully used to complement the experimental techniques to suggest a catalytic mechanism and to identify all stationary points including transition states for both O-O bond formation and O2 release. In this review, we discuss the recent progress in the applications of the quantum chemical methods for the modeling of homogeneous water oxidation catalysis, covering various transition metals, including Mn, Fe, Co, Ni, Cu, Ru, and Ir.
      PubDate: 2017-09-05T21:26:44.970346-05:
      DOI: 10.1002/cssc.201701374
       
  • Diphenylpyridine Amine-Substituted Porphyrins as Hole-Transporting
           Materials for Perovskite Solar Cells
    • Authors: Un-Hak Lee; Randi Azmi, Septy Sinaga, Sunbin Hwang, Seung Hun Eom, Tae-Wook Kim, Sung Cheol Yoon, Sung-Yeon Jang, IN HWAN JUNG
      Abstract: The susceptibility of porphyrin derivatives to light-harvesting and charge-transport operations have enabled these materials to be employed in solar cell applications. The potential of porphyrin derivatives as hole-transporting materials (HTMs) for perovskite solar cells (PSCs) has recently been demonstrated, but research on the relationships between the porphyrin structure and device performance remains insufficient. In this work, a series of novel porphyrin derivatives, PZn-TPA-O, PZn-TPA, PZn-DPPA-O and PZn-DPPA, are developed and employed as HTMs for low-temperature processed PSCs. In our key design strategy, the electron deficient pyridine moiety was incorporated to down-shift HOMO levels of porphyrin HTMs. The porphyrin HTMs containing diphenylpyridine amine (DPPA) possess HOMO levels which are in good agreement with the perovskite active layers, thus facilitating hole transfers from the perovskite to the HTMs. The DPPA-containing PZn-DPPA based PSCs showed the best performance, with efficiency levels comparable to those of PSCs using spiro-OMeTAD, a current state-of-the-art HTM. In particular, PZn-DPPA based PSCs show superior air-stability in both doped and undoped forms, compared to spiro-OMeTAD based devices.
      PubDate: 2017-09-05T21:26:40.681091-05:
      DOI: 10.1002/cssc.201701526
       
  • Selective and Efficient Iridium Catalyst for the Reductive Amination of
           Levulinic Acid into Pyrrolidones
    • Authors: Shengdong Wang; Haiyun Huang, Christian Bruneau, Cedric Fischmeister
      Abstract: The catalytic reductive amination of Levulinic acid (LA) into pyrrolidones with iridium catalyst using H2 as hydrogen source is reported. The chemoselective iridium catalyst displayed high efficiency for the synthesis of a variety of N-substituted 5-methyl-2-pyrrolidones and N-arylisoindolinones. N-Substituted 5-methyl-2-pyrrolidone was evaluated as a bio-sourced substitute solvent to NMP (N-Methyl-pyrrolidone) in the catalytic arylation of 2-phenylpyridine.
      PubDate: 2017-09-05T12:20:37.784519-05:
      DOI: 10.1002/cssc.201701299
       
  • Co9S8/Co as a High Performance Anode for Sodium Ion Batteries with a
           Preferred Ether-based Electrolyte
    • Authors: Yingying Zhao; Qiang Pang, Yingjin Wei, Luyao Wei, Yanming Ju, Bo Zou, Yu Gao, Gang Chen
      Abstract: Co9S8 has been regarded as a desirable anode material for sodium ion batteries because of its high theoretical capacity. In this study, a Co9S8 anode material containing 5.5 wt% Co (Co9S8/Co) was prepared by a solid-state reaction. The material's electrochemical properties were studied with carbonate-based and ether-based electrolytes (the latter, EBE), which showed that the material had a longer cycling life and better rate capability in the EBE. This excellent electrochemical performance was attributed to the low apparent activation energy and the low over-potential for Na deposition in the ether based electrolyte, which improved the electrode kinetic properties. Also, EBE suppressed side reactions of the electrode and electrolyte, which avoided the formation of a solid electrolyte interphase film.
      PubDate: 2017-09-05T07:24:27.258399-05:
      DOI: 10.1002/cssc.201701334
       
  • Biocatalytic valorization of Furans: Opportunities for inherently unstable
           substrates.
    • Authors: Pablo Dominguez de Maria; Nadia V. Guajardo
      Abstract: Biogenic furans (Furfural and 5-hydroxymethylfurfural) are expected to become relevant building blocks based on their high functionalization and versatility. However, the inherent instability of furans poses considerable challenges for their synthetic modifications. Valorization routes of furans typically generate by-products, impurities, wastes, and a cumbersome downstream processing, compromising their ecological footprint. Biocatalysis may become an alternative, given the high selectivity of enzymes, together with the mild reaction conditions applied. This review critically discusses the options for enzymes in the upgrading of furans. Based on the reported literature, there is a variety of biocatalytic transformations applied to furans, with successful cases both in aqueous and in water-free media. Options comprise the biodetoxification of toxic furans in hydrolysates, selective syntheses based on oxidation-reduction processes, solvent-free esterifications, or carboligations to afford C12 derivatives. Reported strategies show in general promising but still modest productivities (range of 2-30 g product L-1 d-1, depending on the example). There are opportunities with high potential, deserving further development, scale-up and techno-economic assessment, to entirely validate them as realistic alternatives.
      PubDate: 2017-09-04T12:15:32.060844-05:
      DOI: 10.1002/cssc.201701583
       
  • Electrocatalytic water oxidation by MnOx@C: in-situ catalyst formation,
           carbon substrate variations and direct O2 / CO2 monitoring by
           membrane-inlet mass-spectrometry
    • Authors: Jens Melder; Wai Ling Kwong, Dimitriy Shevela, Johannes Messinger, Philipp Kurz
      Abstract: Layers of amorphous manganese oxides were directly formed on the surfaces of different carbon materials by exposing the carbon to aqueous solutions of permanganate (MnO4-) followed by sintering at 100 - 400°C. During electrochemical measurements in neutral aqueous buffer, nearly all of the Mn-oxide@Carbon electrodes show significant oxidation currents at potentials relevant for the oxygen-evolution reaction (OER). However, by combining electrolysis with product detection using mass-spectrometry, it was found that these currents were only strictly linked to water-oxidation where MnOx was deposited on graphitic carbon materials (faradaic O2 yields>90%). On the contrary, supports containing sp³-C's were found to be unsuitable as the OER is accompanied by carbon corrosion to CO2. Thus, choosing the "right" carbon material is crucial for the preparation of stable and efficient MnOx@C-anodes for water-oxidation catalysis. For MnOx on graphitic substrates, current densities of>1mA·cm-2 at η = 540 mV could be maintained for at least 16 h of continuous operation at pH 7 (very good values for electrodes containing only abundant elements like C, O and Mn) and post-operando measurements proved the integrity of both the catalyst coating and the underlying carbon at OER conditions.
      PubDate: 2017-09-04T10:15:32.275611-05:
      DOI: 10.1002/cssc.201701383
       
  • Anodic dissolution of Al current collectors in unconventional solvents for
           high voltage electrochemical double layer capacitors
    • Authors: Jakob Krummacher; Lars Henning Hess, Andrea Balducci
      Abstract: This study investigated the anodic dissolution of Al current collectors in unconventional electrolytes for high voltage electrochemical double layer capacitors (EDLC) containing adiponitrile (ADN), 3-cyanopropionic acid methyl ester (CPAME), 2-methyl-glutaronitrile (2-MGN) as solvent, and tetraethylammonium tetrafluroroborate (Et4NBF4) and tetraethylammonium bis(trifluoromethanesulfonyl)imide (Et4NTFSI) as conductive salts. In order to have a comparison with the state-of-the-art electrolytes, the same salts were also used in combination with acetonitrile (ACN). The chemical-physical properties of the electrolytes were investigated. Furthermore, their impact on the anodic dissolution of Al was analysed in detail, as well as the influence of this process on the performance of high voltage EDLCs. The results of this study indicated that in the case of Et4NBF4-based electrolytes the use of alternative solvent is very beneficial for the realization of stable devices. When Et4NTFSI is used, the reduced solubility of the complex Al(TFSI)3 appears to be the key for the realization of advanced electrolytes.
      PubDate: 2017-09-04T05:18:54.101189-05:
      DOI: 10.1002/cssc.201701422
       
  • High photoluminescence quantum yield in organic semiconductor-perovskite
           composite thin films
    • Authors: Giulia Longo; Maria-Grazia La-Placa, Michele Sessolo, Henk J. bolink
      Abstract: One of the obstacles to allow efficient radiative recombination in hybrid perovskites is their low exciton binding energy, typically in the orders of tens of meV. It has been shown that the use of electron-donor additives can lead to a substantial reduction of the non-radiative recombination in perovskite films. We expand this approach to the use of small molecules with semiconducting properties, which are candidate to be implemented in future optoelectronic devices. In particular, we have developed highly luminescent perovskite/organic semiconductors composite thin films, which can be processed from solution in a simple coating step. By tuning the relative concentration of MAPbBr3 and SPPO1, we showed that it is possible to achieve PLQY as high as 85%, thanks to dual function of SPPO1, which limit the grain growth while passivating the perovskite surface. The electroluminescence of these materials was investigated by fabricating multilayer LEDs, where the charge injection and transport was found to be severely hindered in the presence of solely the perovskite and SPPO1. This was alleviated by partially substituting the SPPO1 with a hole transporting material, mCP, leading to bright electroluminescence. This work shows the potential of combining perovskite and organic semiconductors in order to achieve materials with improved properties, and open new venues for the preparation of simple light-emitting devices using perovskites as the emitter.
      PubDate: 2017-09-04T04:15:23.443926-05:
      DOI: 10.1002/cssc.201701265
       
  • Cascade Reductive-Etherification of Bio-derived Aldehydes over Zr-based
           Catalysts
    • Authors: Suhas Shinde; Chandrashekhar V. Rode
      Abstract: A single pot, efficient catalytic cascade sequence is developed for the production of value-added ethers from bio-derived aldehydes. Etherification of 5-(hydroxymethyl)furfural with different aliphatic alcohols over acidic Zr-Montmorillonite (Zr-Mont) catalyst, produced a mixture of 5-(alkoxymethyl)furfural and 2-(dialkoxymethyl)-5-(alkoxymethyl)furan. The later was selectively converted back to 5-(alkoxymethyl)furfural by treating it with water over the same catalyst. Synthesis of 2,5-bis(alkoxymethyl)furan was successfully achieved through a cascade sequence involving etherification, transfer hydrogenation and re-etherification over a combination of acidic catalyst (Zr-Mont) and CTH catalyst [ZrO(OH)2]. This catalyst combination was further successfully explored for cascade conversion of 2-furfuraldehyde into 2-(alkoxymethyl)furan. The scope of this strategy was then extended for reductive-etherification of lignin derived arylaldehydes to get respective benzyl ethers in> 80% yield. Additionally, the mixture of Zr-Mont and ZrO(OH)2 doesn't undergo mutual destruction which was proved by recycle experiments and XRD analysis. Both the catalysts were thoroughly characterized using BET, NH3-TPD, CO2-TPD, pyridine-FTIR, XRD, XPS and ICP-OES techniques.
      PubDate: 2017-09-04T03:25:47.202509-05:
      DOI: 10.1002/cssc.201701275
       
  • Effect of FA/Cs Substitution and PbI2 on the Long Term Stability of Triple
           Cation Perovskites
    • Authors: Shashwat Shukla; Sudhanshu Shukla, Lew Jia Haur, Harsha Satya Sai, Guifang Han, Anish Priyadarshi, Tom Baikie, Subodh Mhaisalkar, Nripan Mathews
      Abstract: Altering cation and anion ratios in perovskites has been an excellent avenue in tuning the perovskite properties and enhancing the performance. Recently, MA/FA/Cs triple cation mixed halide perovskites have demonstrated efficiencies reaching up to 22 %. Similar to the widely explored MAPbI3, excess PbI2 is added in these perovskite films to enhance the performance. Previous reports demonstrate that the excess PbI2 is beneficial for the performance. However, not much work has been conducted about its impact on stability. Triple cation perovskites (TCP) deploy excess PbI2 up to 8 %. Thus, it is imperative to analyze the role of excess PbI2 in the degradation kinetics. In this paper, we have varied the amount of PbI2 in the triple cation perovskite films and monitored the degradation kinetics by X-ray diffraction (XRD) and optical absorption spectroscopy. We found that the inclusion of excess PbI2 adversely affects the stability of the material. Faster degradation kinetics is observed for higher PbI2 samples. However, excess PbI2 samples showed superior properties such as enhanced grain sizes and better optical absorption. Thus, careful management of the PbI2 quantity is required to obtain better stability and alternative pathways should be explored to achieve better device performance rather than adding excess PbI2.
      PubDate: 2017-09-03T21:31:24.45687-05:0
      DOI: 10.1002/cssc.201701203
       
  • Modulating Crystallinity of Graphitic Carbon Nitride for Photocatalytic
           Oxidation of Alcohols
    • Authors: Min Zhou; Pengju Yang, Rusheng Yuan, Abdullah M. Asiri, Muhammad Wakeel, Xinchen Wang
      Abstract: Exploiting efficient photocatalysts with strengthened structure properties for solar-driven alcohol oxidation is of great significance. Herein, we found that the photocatalytic performance of graphitic carbon nitrides can be sharply promoted by modulating the crystallinity. Results confirmed that the high crystallinity accelerates the separation and transfer of photogenerated charge carriers, thus providing more free-charges for photoredox reactions. More importantly, the crystallinity facilitated the adsorption of benzyl alcohol and desorption of benzyl aldehyde, and simultaneously lowered the energy barrier for O2 activation. As a result, the crystalline carbon nitride exhibited ~ 12-fold promotion with respect to the normal carbon nitride. The remarkable enhancement of activity can be attributed to the synergistic effects of the increased electron/hole separation and boosted surface reaction kinetic. These findings will open up new opportunities in modulating the structure of the polymers for a wide variety of organic transformations.
      PubDate: 2017-09-03T21:20:37.848231-05:
      DOI: 10.1002/cssc.201701392
       
  • Evident Improvement of Electrochemical Water Oxidation by Fine Tuning the
           Structure of Tetradentate N4 Ligands of Molecular Copper Catalysts
    • Authors: Junyu Shen; Mei Wang, Jinsuo Gao, Hongxian Han, Hong Liu, Licheng Sun
      Abstract: Two copper complexes, [L1Cu(OH2)](BF4)2 [1, L1 = N,N′-dimethyl-N,N′-bis(pyridin-2-ylmethyl)-1,2-diaminoethane] and [L2Cu(OH2)](BF4)2 [2, L2 = 2,7-bis(2-pyridyl)-3,6-diaza-2,6-octadiene], were prepared as molecular water oxidation catalysts. Complex 1 displayed an overpotential (η) of 1.07 V at 1 mA cm−2 and an observed rate constant (kobs) of 13.5 s−1 at η 1.0 V in pH 9.0 phosphate buffer solution, while 2 exhibited a significantly smaller η (0.70 V) to reach 1 mA cm−2 and a higher kobs (50.4 s−1) than 1 under identical test conditions. Additionally, 2 displayed a better stability than 1 in controlled potential electrolysis experiments in a Faradaic efficiency of 94% for O2 evolution at 1.58 V, when a casing tube was used for Pt cathode. The possible mechanism for 1- and 2-catalyzed O2 evolution reactions is discussed based on the experimental evidence. These comparative results indicate that fine tuning structures of tetradentate N4 ligands can bring about significant change in the performance of copper complexes for electrochemical water oxidation.
      PubDate: 2017-09-03T21:20:22.614833-05:
      DOI: 10.1002/cssc.201701458
       
  • Aqueous and Template-Free Synthesis of Meso-Macroporous Polymers for
           Highly Selective Capture and Conversion of CO2
    • Authors: Kuan Huang; Fujian Liu, Lilong Jiang, Sheng Dai
      Abstract: Meso-macroporous polymers possessing nitrogen functionality were innovatively synthesized via an aqueous and template-free route in this work. Specifically, the polymerization of 1-(4-vinylbenzyl)-1,3,5,7-tetraazaadamantan-1-ium chloride in aqueous solutions under high temperatures induces the decomposition of hexamethylenetetramine unit into ammonia and formaldehyde molecules, followed by the cross-linking of benzene rings via "resol chemistry". During this process, extended meso-macroporous frameworks were constructed, and meanwhile active nitrogen species were incoporated. Taking the advantage of meso-macroporosity and nitrogen functionality, the synthesized polymers offer competitive CO2 capacities (0.37−1.58 mmol/g at 0˚C and 0.15 bar) and extraodinary CO2/N2 selectivities (155−324 at 0 ˚C). Furthermore, after complexed with metal ions, the synthesized polymers show excellent activity for catalyzing the cycloaddition of propylene oxide with CO2 (Yield>98.5%, TOF: 612.9−761.1 h-1)
      PubDate: 2017-09-01T23:25:45.676774-05:
      DOI: 10.1002/cssc.201701666
       
  • Visible-light Homogeneous Photocatalytic Conversion of CO2 to CO in
           Aqueous Solutions with an Fe Catalyst
    • Authors: Marc Robert; Heng Rao, Julien Bonin
      Abstract: We used an iron substituted tetraphenyl porphyrin bearing positively charged trimethylammonio groups at the para position of each phenyl ring for the photoinduced conversion of CO2. This complex is water soluble and acts as a molecular catalyst to selectively reduce CO2 into CO under visible light irradiation in aqueous solutions (acetonitrile:water 1:9 v:v) with the assistance of purpurin, a simple organic photosensitizer. CO is produced with a catalytic selectivity of 95% and turnover up to 120, illustrating the possibility of photo-catalysing the reduction of CO2 in aqueous solution using visible light, a simple organic sensitizer coupled to an amine as sacrificial electron donor and an earth abundant metal based molecular catalyst.
      PubDate: 2017-09-01T07:20:22.966433-05:
      DOI: 10.1002/cssc.201701467
       
  • Al2O3 Underlayer Prepared by Atomic Layer Deposition for Efficient
           Perovskite Solar Cells
    • Authors: Jinbao Zhang; Adam Hultqvist, Tian Zhang, Liangcong Jiang, Changqing Ruan, Li Yang, Yibing Cheng, Marika Edoff, Erik Johansson
      Abstract: Perovskite solar cells, as a newly emerged solar energy conversion technology, have attracted tremendous attention in the solar cell community by demonstrating impressive enhancement in power conversion efficiencies. However, the high temperature and manually processed TiO2 underlayer prepared by spray pyrolysis has significantly limited the large-scale application and device reproducibility of the perovskite solar cells. Here, we for the first time utilize low-temperature atomic layer deposition (ALD) to prepare a compact Al2O3 underlayer for perovskite solar cells. The thickness of the Al2O3 layer can be controlled well by adjusting the deposition cycles during the ALD process. An optimal Al2O3 layer can effectively block the electron recombination at the perovskite/FTO interface as well as sufficiently transport the electrons via tunneling. Perovskite solar cells fabricated with an Al2O3 layer demonstrated the highest efficiency of 16.2% for 50 cycles of ALD (~5 nm), which is a significant improvement over the underlayer free PSCs which have an efficiency of 11.0%. Detailed characterization confirms that the thickness of the Al2O3 underlayer significantly influences the charge transfer resistance and electron recombination process in the devices. Furthermore, this work successfully shows the feasibility of using a high-bandgap semiconductor like Al2O3 as the underlayer in perovskite solar cells and opens up pathways to use ALD Al2O3 underlayers for flexible solar cells.
      PubDate: 2017-08-31T03:21:30.971583-05:
      DOI: 10.1002/cssc.201701160
       
  • Green solvent system for fabricating bismuth based lead-free
           (CH3NH3)3Bi2I9 perovskite photovoltaics with open circuit voltage over 0.8
           V
    • Authors: Congcong Wu; Haijin Li
      Abstract: The toxicity of lead present in organohalide perovskites and the hazardous solvent system used for their synthesis hinders the deployment of perovskite solar cells (PSCs). Here, we report an environmentally friendly route for synthesis of bismuth based lead-free (CH3NH3)3Bi2I9 perovskites that utilize ethanol as the solvent. Using this method, dense and homogeneous microstructure was obtained, compared the porous rough microstructure obtained by DMF solution. Thus, the photovoltaic performance was enhanced and open voltage as high as 0.84 V can be obtained.
      PubDate: 2017-08-30T14:20:21.933519-05:
      DOI: 10.1002/cssc.201701470
       
  • Three-dimensional Porous Nickel-Cobalt Nitrides Supported on Ni Foam as
           Efficient Electrocatalysts for Overall Water Splitting
    • Authors: Jintao Zhang; Yueqing Wang, Baohua Zhang, Wei Pan, Houyi Ma
      Abstract: Exploring highly efficient and durable bifunctional electrocatalyst from the earth-abundant low-cost transition metals is central to obtain clean hydrogen energy via the large scale electrolytic water splitting. Herein, we demonstrate in-situ synthesis of porous nickel-cobalt nitride nanosheets on macroporous Ni foam (NF) via a facile electro-deposition process followed by one-step annealing process in NH3 atmosphere. The transformation from metal hydroxide to metal nitride could efficiently enhance the electrocatalytic performance for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Interestingly, we found that the incorporation of nickel could further boost the catalytic activity of cobalt nitride. Typically, when used as bifunctional electrocatalysts, the obtained nickel-cobalt nitride electrocatalyst shows superior catalytic performance toward both HER and OER with a low overpotential of 0.29 and 0.18 V to achieve a current density of 10 mA cm-2, respectively and good stabilities. The good electrocatalytic performance was also evidenced by the as-fabricated electrolyzer for overall water splitting, exhibiting a high gas generation rate for hydrogen and oxygen with the excellent stability in the prolonged alkaline water electrolysis. The present work provides an efficient approach to preparing 3D interconnected porous nickel-cobalt nitride network with exposed inner active sites for overall water splitting.
      PubDate: 2017-08-30T10:20:27.826612-05:
      DOI: 10.1002/cssc.201701456
       
  • Cobalt-Doping to Boost the Electrochemical Properties of Ni@Ni3S2 Nanowire
           Films for High-Performance Supercapacitors
    • Authors: Shusheng Xu; Tao Wang, Yujie Ma, Wenkai Jiang, Shuai Wang, Min Hong, Nantao Hu, Yanjie Su, Yafei Zhang, Zhi Yang
      Abstract: Metal sulfides have aroused great interest for energy storage. However, low specific capacity and inferior rate capability hinder their practical applications. In this work, we demonstrate a facile cobalt-doped (Co-doped) process to boost the electrochemical performance of Ni@Ni3S2 core−sheath nanowire film electrodes for high-performance electrochemical energy storage. Co ions are successfully and uniformly doped to Ni3S2 nanosheets by a facile ion exchange process. The electrochemical properties of film electrodes are greatly improved with ultrahigh volumetric capacity (increased from 105 to 730 C cm-3 at 0.25 A cm-3) and excellent rate capability after Co is doped to Ni@Ni3S2 core−sheath nanowires. A hybrid asymmetric supercapacitor using Co-doped Ni@Ni3S2 as positive electrode and graphene-carbon nanotubes as negative electrode is assembled which exhibits a ultrahigh volumetric capacitance of 142 F cm-3 (based on the total volume of both electrodes) at 0.5 A cm-3 and excellent cycle stability (only 3% capacitance decrease after 5000 cycles). Moreover, the volumetric energy density can reach up to 44.5 mWh cm-3, this value is much larger than those of as-reported thin film lithium batteries (1−10 mWh cm-3). These results revealed in our work may give an insight into high-performance film electrodes fabrication for energy storage applications
      PubDate: 2017-08-30T07:21:21.554582-05:
      DOI: 10.1002/cssc.201701305
       
  • Insight into aluminium sulfate catalyzed xylan conversion to furfural in
           γ-valerolactone/water biphasic solvent under microwave condition
    • Authors: Tao Yang; Yi-Han Zhou, Sheng-Zhen Zhu, Hui Pan, Yao-Bing Huang
      Abstract: A simple and efficient biphasic system with earth-abundant metal salt catalyst was reported to produce furfural from xylan with a high yield up to 87.8% under microwave condition. Strikingly, the metal salt Al2(SO4)3 exhibited excellent catalytic activity for xylan conversion due to its appropriate combination of Lewis and Brønsted acidity, and as well as a good phase separation promoter. The critical role of SO42- anion was firstly emphasized, which determined the aforementioned characteristic when combining with Al3+ cation. The solvents with γ-valerolactone (GVL) as organic phase provided the highest furfural yield, resulting from its good dielectric properties and dissolving capacity that facilitated the absorption of microwave energy and promoted mass transfer. Mechanistic studies suggested that the xylan-to-furfural conversion proceeded mainly via a hydrolysis-isomerization-dehydration pathway and the hexa-coordinated Lewis acidic [Al(OH)2(aq)]+ species were the active sites for xylose-xylulose isomerization. Detailed kinetic studies of the subreaction for xylan conversion revealed the regulatory role of GVL on the reaction rates and pathways, by promoting the rates of the key steps involved for furfural production and suppressed the side reactions for humin production. Finally, Al2(SO4)3 catalyst was successfully used for the production of furfural from several lignocellulosic feedstocks, revealing its great potential of being used for other biomass conversions.
      PubDate: 2017-08-30T03:20:33.569379-05:
      DOI: 10.1002/cssc.201701290
       
  • Design and Evaluation of a Boron Dipyrrin (BODIPY) Electrophore for Redox
           Flow Batteries
    • Authors: Niklas Heiland; Clemens Cidarér, Camilla Rohr, Piescheck Mathias, Johannes Ahrends, Martin Bröring, Uwe Schröder
      Abstract: A BODIPY (boron dipyrrin) dye was designed as a molecular single component electrophore in a redox flow battery. All positions at the BODIPY core were assessed from literature data, in particular from cyclic voltammetry and density functional calculations, and a minimum requirement substitution pattern accounting for solubility, aggregation, radical cation and anion stabilities, a large potential window, and synthetic accessibility was designed. In depths electrochemical and physical studies of this electrophore revealed suitable cathodic behavior and stability of the radical anion, but rapid anodic decomposition of the radical cation. Three products which formed under the conditions of controlled oxidative electrolysis were isolated and their structures determined by spectroscopy and comparison with a synthetic model compound. From these structures a benzylic radical reactivity, initiated by one-electron oxidation, was concluded to play the major role in this unexpected decomposition.
      PubDate: 2017-08-29T02:15:22.6456-05:00
      DOI: 10.1002/cssc.201701109
       
  • Facile Spray Pyrolysis Synthesis of Yolk-shell Earth-abundant Elemental
           NiFe-based Nanohybrid Electrocatalysts for Full Water Splitting
    • Authors: Zhenhai Wen; Hao Li, Suqin Ci, Mengtian Zhang, Junxiang Chen, Keyuan Lai
      Abstract: It is critical while remains a daunting challenge in the development of high-activity electrocatalysts for water splitting that comprise only inexpensive, earth-abundant elements. In this work, the preparation of yolk-shell Ni3Fe/Ni3FeN was developed by a possible scale-up method using spray pyrolysis technique. The yolk-shell Ni3Fe/Ni3FeN presents excellent catalytic activity for OER and HER with overpotentials of 268 mV and 166 mV at 10 mA cm-2, respectively, and bears a prominent electrochemical durability. The overall water splitting on the electrolyzer with yolk-shell Ni3Fe/Ni3FeN as cathode and anode only requires a cell voltage of 1.62 V to reach current density of 10 mA cm-2. The present research not only proposes a new route in synthesizing advanced functional electrocatalysts for overall water splitting but also shed light on its potential commercial application.
      PubDate: 2017-08-28T09:16:37.643301-05:
      DOI: 10.1002/cssc.201701521
       
  • Electrolyte engineering toward efficient water splitting at mild pH
    • Authors: Tatsuya Shinagawa; Marcus Tze-Kiat Ng, Kazuhiro Takanabe
      Abstract: The development of processes for the conversion of H2O/CO2 driven by electricity generated in renewable manners is essential to achieve sustainable energy and chemical cycles, in which the electrocatalytic oxygen evolution reaction (OER) is one of the bottlenecks. In this contribution, the influences of the electrolyte molarity and identity on OER at alkaline to neutral pH were investigated at an appreciable current density of ~10 mA cm−2, revealing (1) the clear boundary of reactant switching between H2O/OH− due to the diffusion limitation of OH− and (2) the substantial contribution of the mass transport of the buffered species in buffered mild pH conditions. These findings propose a strategy of electrolyte engineering: tuning the electrolyte properties to maximize the mass-transport flux. The concept was successfully demonstrated for OER as well as overall water electrolysis in buffered mild pH conditions, shedding light on the development of practical solar fuel production systems.
      PubDate: 2017-08-28T06:20:52.251692-05:
      DOI: 10.1002/cssc.201701266
       
  • Photocatalytic CO2-to-CO Conversion by a Copper(II) Quaterpyridine Complex
    • Authors: Marc Robert; Zhenguo Guo, Fei Yu, Ying Yang, Chi-Fai Leung, Siu-Mui Ng, Chiu-Chiu Ko, Claudio Cometto, Tai-Chu Lau
      Abstract: The invention of efficient systems for the photocatalytic reduction of CO2 comprising earth-abundant metal catalysts is a promising approach for the production of solar fuels. One bottleneck is to design highly selective and robust molecular complexes able to transform the gas. The Cu(II) quaterpyridine complex [Cu(qpy)]2+ (1) is found to be a highly efficient and selective catalyst for visible-light driven CO2 reduction in CH3CN using [Ru(bpy)3]2+ as photosensitizer, BIH/TEOA as sacrificial reductant. The photocatalytic reaction is greatly enhanced by the presence of H2O (1-4% v/v), and a TON of>12,400 for CO production can be achieved with 97% selectivity, which is among the highest of molecular 3d CO2 reduction catalysts. Results from Hg-poisoning and dynamic light scattering (DLS) experiments suggest that this photocatalysis is homogenous. To the best of our knowledge 1 is the first example of molecular Cu-based catalyst for the photoreduction of CO2.
      PubDate: 2017-08-25T04:39:30.374325-05:
      DOI: 10.1002/cssc.201701354
       
  • Benzoate Anions-Intercalated Layered Cobalt Hydroxide Nanoarray: An
           Efficient Electrocatalyst for Oxygen Evolution Reaction
    • Authors: Xuping Sun; Xiang Ren, Xuqiang Ji, Zhiang Liu, Gu Du, Abdullah M. Asiri, Xuping Sun, Liang Chen
      Abstract: Efficient oxygen evolution reaction (OER) catalysts are highly desired to improve the overall efficiency of electrochemical water splitting. In this communication, we develop a benzoate anions-intercalated layered cobalt hydroxide nanobelt array on nickel foam (benzoate-Co(OH)2/NF) via a one-pot hydrothermal process. As a three-dimensional electrode, benzoate-Co(OH)2/NF with an expanded interlayer spacing (14.72 Å) drives a high OER catalytic current density of 50 mA cm-2 at an overpotential of 291 mV, outperforming its carbonate anions-intercalated counterpart with a lower interlayer spacing of 8.81 Å (337 mV overpotential at 50 mA cm-2). Moreover, this benzoate-Co(OH)2/NF can maintain its catalytic activity for 21 h.
      PubDate: 2017-08-24T23:35:39.589067-05:
      DOI: 10.1002/cssc.201701358
       
  • Iron-Catalyzed C-O Bond Activation: Opportunity for Sustainable Catalysis
    • Authors: Elwira Bisz; Michal Szostak
      Abstract: Oxygen-based electrophiles have emerged as some of the most valuable cross-coupling partners in organic synthesis due to several major strategic and environmental benefits such as abundance and potential to avoid toxic halide waste. In this context, iron-catalyzed C-O activation/cross-coupling holds particular promise to achieve sustainable catalytic protocols due to its natural abundance, inherent low toxicity, an excellent economic and ecological profile. Recently, tremendous progress has been achieved in the development of new methods for functional group tolerant iron-catalyzed cross-coupling reactions by selective C-O cleavage. These methods establish highly attractive alternatives to traditional cross-coupling reactions using halides as electrophilic partners. In particular, new easily accessible oxygen-based electrophiles have emerged as substrates in iron-catalyzed cross- coupling reactions, which significantly broaden the scope of this catalysis platform. New mechanistic manifolds involving iron catalysis have been established, thus opening vistas for the development of a wide range of unprecedented reactions. The synthetic potential of this sustainable mode of reactivity has been highlighted by the development of new strategies in the construction of complex motifs, including in target synthesis. In this minireview, we discuss the most recent advances in sustainable iron-catalyzed cross-coupling of C-O based electrophiles with a focus on both mechanistic aspects and synthetic utility. It should be noted that this catalytic manifold provides access to motifs that are often not easily available by other methods, such as the assembly of stereodefined dienes or C(sp2)-C(sp3) cross-couplings, emphasizing the synthetic importance of this mode of reactivity.
      PubDate: 2017-08-24T21:35:33.270552-05:
      DOI: 10.1002/cssc.201701287
       
  • Dendritic Fibrous Nanosilica (DFNS) for Catalysis, Energy Harvesting, CO2
           Mitigation, Drug Delivery and Sensing
    • Authors: Ayan Maity; Vivek Polshettiwar
      Abstract: Morphology-controlled nanomaterials such as silica play a crucial role in the development of technologies for addressing challenges in the fields of energy, environment and health. After the discovery of Stöber silica, followed by the discovery of mesoporous silica materials, such as MCM-41 and SBA-15, a significant surge in the design and synthesis of nanosilica with various sizes, shapes, morphologies and textural properties (surface area, pore size and pore volume) has been observed in recent years. One notable invention is dendritic fibrous nanosilica (DFNS), also known as KCC-1. This material possesses a unique fibrous morphology, unlike the tubular porous structure of various conventional silica materials. It has a high surface area with improved accessibility to the internal surface, tunable pore size and pore volume, controllable particle size, and importantly, improved stability. After its discovery, a large number of reports appeared in the literature citing its successful use in a range of applications, such as catalysis, solar energy harvesting (photocatalysis, solar cells, etc.), energy storage, self-cleaning antireflective coatings, surface plasmon resonance (SPR)-based ultra-sensitive sensors, CO2 capture and biomedical applications (drug delivery, protein and gene delivery, bioimaging, photothermal ablation, and Ayurvedic and radiotherapeutics drug delivery, among others). These reports indicate that dendritic fibrous nanosilica has excellent potential as an alternative to popular silica materials such as MCM-41, SBA-15, Stöber silica, and mesoporous silica nanoparticles (MSNs), among others. This review provides a critical survey of the dendritic fibrous nanosilica family of materials, and the discussion includes i) the synthesis and formation mechanism, ii) applications in catalysis and photocatalysis, iii) applications in energy harvesting and storage, iv) applications in magnetic and composite materials, v) applications in CO2 mitigation, v) biomedical applications, and vi) analytical applications (sensing, extraction, and chromatography). Wherever possible, the comparison of dendritic fibrous nanosilica -based materials with conventional mesoporous materials, such as MCM-41, SBA-15, Stöber silica, and MSNs, is presented.
      PubDate: 2017-08-23T09:35:43.602932-05:
      DOI: 10.1002/cssc.201701076
       
  • The effect of the formulation of silicon-based composite anode on its
           mechanical, storage and electrochemical properties
    • Authors: Daniel Bélanger; BIRHANU DESALEGN ASSRESAHEGN
      Abstract: In this work, the effect of the formulation of silicon-based composite anode on its mechanical, storage and electrochemical properties was investigated. The formulation of the electrode was changed by using hydrogenated or modified (through covalent attachment of a binding additive eg. polyacrylic acid) silicon and acetylene black or graphene sheets, as conducting additive. We found that the composite anode with the covalently grafted binder has the highest elongation without break and strong adhesion to the current collector. It was also found that these mechanical properties are significantly dependent on the conductive carbon additive used and that the use of graphene sheets instead of acetylene black can significantly improve elongation and adhesion. Upon storage at ambient conditions during 180 days, the electronic conductivity and discharge capacity of the modified silicon electrode showed a much smaller decrease than the hydrogenated silicon composite electrode suggesting that the modification can play a passivation role to maintain a constant active material composition. Moreover, it was shown that this composite Si anode has high packing density and consequently thin film electrodes having a very high material loading can be prepared without penalizing its electrochemical performance.
      PubDate: 2017-08-23T09:35:28.281898-05:
      DOI: 10.1002/cssc.201701281
       
  • Electrocatalytic Conversion of CO2 and Nitrate Ions to Urea below -1.0 V
           vs Ag/AgCl by a TiO2-Nafion® Composite Electrode
    • Authors: Saravanakumar Duraisamy; Jieun Song, Sunhye Lee, Namhwi Hur, Woonsup Shin
      Abstract: CO2 and nitrate ions were successfully converted to urea by a TiO2/Nafion® nanocomposite electrode under ambient conditions. The composite electrode was constructed by drop-casting the mixture of P-25 titania and Nafion® solution on an ITO electrode. When the electrode was electrolyzed in CO2-saturated 0.1 M KNO3 (pH 4.5) solution at -0.98 V vs. Ag/AgCl, urea was formed with a Faradaic efficiency of 40%. The other reduced products obtained were ammonia, CO, and H2.
      PubDate: 2017-08-23T07:36:15.490408-05:
      DOI: 10.1002/cssc.201701448
       
  • Modulating excitonic recombination effects and improved PLQY through
           one-step synthesis of perovskite nanoparticles for LEDs
    • Authors: Sneha A. Kulkarni; Subas Muduli, Guichuan Xing, Natalia Yantara, Mingjie Li, Chen Shi, Tze Chien Sum, Nripan Mathews, Tim J. White, Subodh G. Mhaisalkar
      Abstract: The primary advantages of halide perovskites for light emitting diodes (LEDs) are solution processability, direct band gap, good charge carrier diffusion lengths, low trap density, and reasonable carrier mobility. The luminescence in three-dimensional (3D) halide perovskite thin films originates from free electron-hole bimolecular recombination. However, the slow bimolecular recombination rate is a fundamental performance limitation. Perovskite nanoparticles could result in improved performance but processability and cumbersome synthetic procedures remain challenges. Herein, these constraints are overcome by tailoring the 3D perovskite as a near monodisperse nanoparticle film laid down via a one step in-situ deposition method. Replacing methyl ammonium bromide (CH3NH3Br, MABr) partially by octyl ammonium bromide (CH3(CH2)7NH3Br, OABr) in defined mole ratios in the perovskite precursor proved crucial for the nanoparticle formation. Films consisting of the in-situ formed nanoparticles displayed signatures associated with excitonic recombination, rather than that of bimolecular recombination associated with 3D perovskites. This transition was accompanied by enhanced PLQY (~20.5% vs 3.40%). PeLEDs fabricated from the nanoparticle films exhibit a one order of magnitude improvement in current efficiency and a doubling in luminance efficiency. This study provides the means to control perovskite morphologies through the selection and mixing of appropriate additives.
      PubDate: 2017-08-23T05:30:45.825235-05:
      DOI: 10.1002/cssc.201701067
       
  • Dry reforming of methane in a gliding arc plasmatron: Towards a better
           understanding of the plasma chemistry
    • Authors: Emelie Cleiren; Stijn Heijkers, Marleen Ramakers, Annemie Bogaerts
      Abstract: We studied the dry reforming of methane in a plasma reactor, called gliding arc plasmatron, for different CH4 fractions in the mixture. The CO2 and CH4 conversions reach their highest values of around 18 and 10 %, respectively, at 25 % CH4 in the gas mixture, corresponding to an overall energy cost of 10 kJ/L (or 2.5 eV/molec) and an energy efficiency of 66 %. CO and H2 are the major products, with some smaller fractions of C2Hx (x= 2, 4 or 6) compounds and H2O formed as well. We also present a chemical kinetics model, to investigate the underlying chemical processes. The calculated CO2 and CH4 conversion and the energy efficiency are in good agreement with the experimental data. The model calculations reveal that the reaction of CO2 (mainly in vibrationally excited levels) with H radicals is mainly responsible for the CO2 conversion, especially at higher CH4 fractions in the mixture, and this explains why the CO2 conversion rises upon rising CH4 fraction. The main process responsible for CH4 conversion is the reaction with OH radicals. The excellent energy efficiency can be explained by the non-equilibrium character of the plasma, where the electrons mainly activate the gas molecules, and by the important role of the vibrational kinetics of CO2. Our results demonstrate that a gliding arc plasmatron is very promising for dry reforming of methane.
      PubDate: 2017-08-22T09:30:26.650034-05:
      DOI: 10.1002/cssc.201701274
       
  • Polymeric Redox Active Electrodes for Sodium Ion Batteries
    • Authors: Naiara Fernández; Paula Sanchez-Fontecoba, Elizabeth Castillo-Martínez, Javier Carretero-González, Teófilo Rojo, Michel Armand
      Abstract: Polymer binding agents are critical for the good performance of the electrodes of sodium and lithium ion batteries during cycling as they hold the electroactive material together forming a cohesive assembly by means of mechanical and chemical stability as well as adhesion to the current collector. Herein, novel redox active polymer binders that insert Na+ ions and show adhesion properties were synthesized by adding polyetheramine blocks (Jeffamine®) based on mixed propylene oxide and ethylene oxide blocks to p-phenylenediamine and terephthalaldehyde units forming electroactive Schiff bases groups along the macromolecule. Synthesis parameters and the electrochemical properties of these terpolymers as sodium ion negative electrodes in half-cells have been studied. Reversible capacities of 300 mAh/g (50 wt. % conducting carbon) and 200 mAh/g (20 wt. % conducting carbon) are achieved, in powder and Cu supported electrodes, respectively for a polySchiff-polyether terpolymer synthesized using a poly(ethylene oxide) block of 600 g/mol, instead of one third of the aniline units. The new redox active polymers were also deployed as binding agent of another anode material (hard carbon), leading to an increase of the total capacity of the electrode compared to other standard fluorinated polymer binders such as polyvinylidene fluoride.
      PubDate: 2017-08-22T07:10:43.900294-05:
      DOI: 10.1002/cssc.201701471
       
  • Angelica Lactones: from Biomass-Derived Platform Chemicals to Value-Added
           Products
    • Authors: Arlene Correa; Carolina G. S. Lima, Júlia Monteiro, Thiago Melo Lima, Marcio Webber Paixão
      Abstract: The upgrading of biomass-derived compounds has arisen in recent years as a very promising research field in both academia and industry. In this sense, a lot of new processes and products have been developed, often involving levulinic acid as a starting material or intermediate. In the last few years, though, other scaffolds have been receiving growing attention, in special, angelica lactones. Considering these facts and the emergent applications of said molecules, in this review we will discuss their preparation and applications - the use of these frameworks as starting materials in organic synthesis to produce potential bioactive compounds will be covered, as well as their arising use as the foundation to highly regarded compounds such as liquid alkanes with prospective use as fuels and polymers.
      PubDate: 2017-08-21T10:00:39.20312-05:0
      DOI: 10.1002/cssc.201701469
       
  • Interfacial heterojunction engineering of ZnIn₂S₄/MoSe₂ hierarchical
           nanoarchitectures for highly efficient noble-metal-free photocatalytic
           hydrogen evolution under visible light
    • Authors: Deqian Zeng; Lang Xiao, Wee-Jun Ong, Pengyuan Wu, Hongfei Zheng, Yuanzhi Chen, Dong-Liang Peng
      Abstract: Exploiting a highly efficient visible-light-driven photocatalyst is an urgent necessity for photocatalytic hydrogen (H₂) generation from water splitting. Herein, flower-like ZnIn₂S₄ hierarchical architectures assembled by ultrathin nanosheets were synthesized by a facile one-pot polyol approach, and subsequently, the colloidally developed two-dimensional (2D) network-like MoSe₂ was successfully hybridized with ZnIn₂S₄ via a facile hybridization approach by taking advantage of their analogues intrinsic layered morphologies. The ZnIn₂S₄/MoSe₂ heterostructures show enhanced noble-metal-free photocatalytic H₂ evolution compared to pure ZnIn₂S₄. It is noteworthy that the optimum nanocomposite of ZnIn₂S₄/2%MoSe₂ photocatalyst displays a dramatically high H₂ generation rate of 2228 μmol g¯¹ h¯¹ and an apparent quantum yield (AQY) of 21.39% at 420 nm. This study presents an unprecedented ZnIn₂S₄/MoSe₂ metal-sulfide/metal-selenide hybrid system for remarkable H₂ evolution. Importantly, the present efficient hybridization strategy uncovers a huge potential in the construction of hierarchical nanoarchitectures for a multitude of energy storage and solar energy conversion applications.
      PubDate: 2017-08-18T07:00:33.267296-05:
      DOI: 10.1002/cssc.201701345
       
  • Synthesis of renewable lubricant alkanes from biomass-derived platform
           chemicals
    • Authors: Mengyuan Gu; Qineng Xia, Xiaohui Liu, Yong Guo, Yanqin Wang
      Abstract: Catalytic synthesis of liquid alkanes from renewable biomass has received tremendous attention in recent years. However, highly branched lubricant alkanes are not yet synthetically exploited from biomass and are currently produced by hydrocracking and hydroisomerization of long-chain n-paraffins. Here we describe a selective catalytic synthetic route for the production of highly branched C23 alkanes for lubricant base oil component from biomass-derived furfural and acetone, through a tandem four-step process, namely aldol condensation of furfural with acetone to produce a C13 double adduct, then selective hydrogenation to a C13 ketone, followed by a second condensation of the C13 ketone with furfural to generate a C23 aldol adduct and finally to highly branched C23 alkanes by hydrodeoxygenation. The overall yield of C23 alkanes reaches in 50.6% (97.9%×72.8%×83.8%×84.8%) from furfural. This work opens a general strategy for the synthesis of high-quality lubricant alkanes from renewable biomass.
      PubDate: 2017-08-18T05:00:23.410735-05:
      DOI: 10.1002/cssc.201701200
       
  • Nanoparticles embedded in amphiphilic membranes for CO2 separation and
           dehumidification
    • Authors: Wai Fen YONG; Yan Xun Ho, Tai-Shung Chung
      Abstract: Polymers containing ethylene oxide groups have gained significant interest as the ethylene oxide groups have favorable interactions with polar molecules such as H2O, quadrupolar molecules such as CO2 and metal ions. However, the main challenges of poly(ethylene oxide) (PEO) membranes are their weak mechanical properties and high crystallinity nature. The amphiphilic copolymer made from poly(ethylene oxide) terephthalate and poly(butylene terephthalate) (PEOT/PBT) comprising both hydrophilic and hydrophobic segments. The hydrophilic PEOT segment is thermosensitive that facilities gas transports while the hydrophobic PBT segment is rigid that provides mechanical robustness. This work demonstrates a novel strategy to design amphiphilic mixed matrix membranes (MMMs) by incorporating zeolitic imidazolate framework, ZIF-71, into the PEOT/PBT copolymer. The resultant membrane shows an enhanced CO2 permeability with an ideal CO2/N2 selectivity surpassing the original PEOT/PBT and Robeson's Upper bound line. The nanoparticles embedded amphiphilic membranes exhibit characteristics of high transparency and mechanical robustness. Mechanically strong composite hollow fiber membranes consisting PEOT/PBT/ZIF-71 as the selective layer have also been prepared. The resultant hollow fibers possess an excellent CO2 permeance of 131 GPU, CO2/N2 selectivity of 52.6, H2O permeance of 9,300 GPU and H2O/N2 selectivity of 3,700, showing great potential for industrial CO2 capture and dehumidification.
      PubDate: 2017-08-17T11:25:24.58133-05:0
      DOI: 10.1002/cssc.201701405
       
  • Synthetic Manipulation of Hybrid Perovskite Systems in Search of Novel and
           Enhanced Functionalities
    • Authors: Rounak Naphade; Satyawan Nagane, Umesh Bansode, Mukta Tathavadekar, Aditya Sadhanala, Satishchandra B. Ogale
      Abstract: Over the past few years the organic/Inorganic hybrid perovskite systems have emerged as a promising class of materials for photo-voltaic and electroluminescent thin film device applications, in view of their unique set of tunable optoelectronic properties. Importantly, these materials can be easily solution-processed at low temperatures and as such are amenable to facile molecular engineering. Thus, a variety of low dimensional forms and quantum structures of these materials can be obtained through strategic synthetic manipulations via small molecule incorporation or molecular ion doping. In this mini review, we specifically focus on these approaches and outline the possibilities of utilizing these for enhanced functionalities and newer application domains.
      PubDate: 2017-08-13T21:25:26.044652-05:
      DOI: 10.1002/cssc.201701093
       
  • Self-Co-Catalyzed Fluorine-Doped Hematite Nanocrystal for Efficient Water
           Oxidation
    • Authors: Yi Xie; Junfeng Xie, Weiwei Liu, Jianping Xin, Fengcai Lei, Li Gao, Haichao Qu, Xiaodong Zhang
      Abstract: Herein, enhanced light absorption and oxygen-evolving activity were simultaneously achieved by doping fluorine anions into hematite nanocrystals. With the merits of anion doping, the band structure of hematite can be effectively regulated, leading to the generation of defect level between the bandgap and remarkably increased visible light absorption. In addition, the activity for electrocatalytic oxygen evolution reaction (OER) of the hematite nanocrystals exhibits obvious enhancement after fluorine doping, making the doped hematite play as an effective self-co-catalyst for photoelectrochemical water splitting. The optimization strategy proposed in this work by simultaneously tuning the intrinsic OER activity and light absorption may shed light on the future design of photocatalysts for energy-related applications.
      PubDate: 2017-08-12T02:25:29.241701-05:
      DOI: 10.1002/cssc.201701074
       
  • Electrochemical Reduction of Carbon Dioxide in a Monoethanolamine Capture
           Medium
    • Authors: Jie Zhang; Lu Chen, Fengwang Li, Ying Zhang, Cameron Bentley, Mike Horne, Alan Bond
      Abstract: Electrocatalytic reduction of CO2 present in a 30% (w/w) monoethanolamine (MEA) aqueous solution has been undertaken at In, Sn, Bi, Pb, Pd, Ag, Cu and Zn metal electrodes. Upon dissolution of CO2, the non-conducting MEA solution is transformed into a conducting one, as needed for electrochemical reduction of CO2. Both an increase in the electrode surface porosity and addition of surfactant cetyltrimethylammonium bromide (CTAB) suppress the competing hydrogen evolution reaction with the latter having a significantly stronger impact. The combination of a porous metal electrode and 0.1% (w/w) of CTAB allows molecular CO2 to be reduced to CO and formate ([HCOO]-) with the product distribution being highly dependent on the identity of the metal electrode used. At a potential of -0.8 V vs. RHE, and use of coralline-like structured indium electrode, faradaic efficiencies for generation of CO and [HCOO]- are 22.8% and 54.5%, respectively compared to efficiencies of 2.9% and 60.8% with a porous lead electrode and 38.2% and 2.4% with a porous silver electrode. Extensive data for the other 5 electrodes are also provided. In addition to identifying optimal conditions for CO2 reduction, mechanistic details for reaction pathways are proposed in this proof of concept electrochemical study in a CO2 capture medium. Conditions and features needed to achieve industrially and commercially viable CO2 reduction in an amine based capture medium are considered.
      PubDate: 2017-08-10T21:25:32.953267-05:
      DOI: 10.1002/cssc.201701075
       
  • New Insights into the Hydrothermal Stability of Triamine-Functionalized
           SBA-15 Silica for CO2 Adsorption
    • Authors: Masoud Jahandar Lashaki; Hessam Ziaei-Azad, Abdelhamid Sayari
      Abstract: The hydrothermal stability of triamine-grafted, large-pore SBA-15 CO2 adsorbents was studied using steam stripping. Following two 3-h cycles of steam regeneration, lower CO2 uptakes, lower CO2/N ratios, and slower adsorption kinetics were observed relative to fresh samples, particularly at the lowest adsorption temperature (25 oC). CO2 adsorption measurements for a selected sample exposed to 48 h of steam stripping depicted that after the initial loss during the first exposure to steam (3 to 6 h), the adsorptive properties stabilized. For higher adsorption temperatures (i.e., 50 and 75 oC), however, all adsorptive properties remained almost unchanged after steaming, indicating the significance of diffusional limitations. TGA and FT-IR spectroscopy results for grafted samples before and after steam stripping showed no amine leaching and no change in the chemical nature of the amine groups, respectively. However, N2 adsorption measurement at 77 K showed significant reductions in the BET surface area of the grafted samples following steaming. Based on the pore size distribution of calcined, grafted samples before and after steaming, it is proposed that exposure to steam restructured the grafted materials, causing mass transfer resistance. It is inferred that triamine-grafted, large-pore SBA-15 adsorbents are potential candidates for CO2 capture at relatively high temperatures (50 to 75 oC; e.g. flue gas) combined with steam regeneration.
      PubDate: 2017-08-08T10:15:28.531151-05:
      DOI: 10.1002/cssc.201701439
       
  • Catalyst particle density controls hydrocarbon product selectivity in CO2
           electroreduction on CuOx
    • Authors: Xingli Wang; Ana Sofia Varela, Arno Bergmann, Stefanie Kuehl, Peter Strasser
      Abstract: A key challenge of the carbon dioxide electroreduction (CO2RR) on Cu-based nanoparticles is its low faradic selectivity towards higher-value products such as ethylene. Here, we demonstrate a facile method for tuning the hydrocarbon selectivities on CuOx nanoparticle ensembles by varying the nanoparticle areal density. The sensitive dependence of the experimental ethylene selectivity on catalyst particle areal density is attributed to a diffusional interparticle coupling which controls the de- and re-absorption of CO and thus the effective coverage of COad intermediates. Thus, higher areal density constitutes dynamically favoured conditions for CO re-adsorption and *CO dimerization leading to ethylene formation independent of pH and applied overpotential.
      PubDate: 2017-08-04T03:00:39.194668-05:
      DOI: 10.1002/cssc.201701179
       
  • CsPb2Br5 Single Crystals: Synthesis and Characterization
    • Authors: Ibrahim Dursun; Michele De Bastiani, Bekir Turedi, Badriah Alamer, Aleksander Shkurenko, Jun Yin, Issam Gereige, Ahmed Alsaggaf, Omar F. Mohammed, Mohamed Eddaoudi, Osman M. Bakr
      Abstract: CsPb2Br5 is a ternary halogen-plumbate material with close characteristics to well-reported halide perovskites. Due to its unconventional two-dimensional structure, CsPb2Br5 is being looked at broadly for potential applications in optoelectronics. CsPb2Br5 investigations are currently limited to nanostructures and powder forms of the material, which present unclear and conflicting optical properties. In this study, we present the synthesis and characterization of CsPb2Br5 bulk single crystals, which enabled us to finally clarify the material's optical features. Our CsPb2Br5 crystal has a two-dimensional structure with Pb2Br5- layers spaced by Cs+ cations, and exhibits a ~3.1 eV indirect bandgap with no emission in the visible spectrum.
      PubDate: 2017-08-01T21:00:37.064473-05:
      DOI: 10.1002/cssc.201701131
       
  • Hindered Amine Light Stabilizers increase stability of Methylammonium Lead
           Iodide Perovskite against Light and Oxygen
    • Authors: Juan L. Delgado; Nevena Marinova, marius Franckevičius, Ieva Matulaitienė, Andrius Devižis, Gediminas Niaura, Vidmantas Gulbinas
      Abstract: Methylammonium lead iodide perovskite (MAPI) is a promising material for highly-efficient photovoltaic devices. However, it suffers from photooxidation, which imposes strict requirements for its protection from oxygen during processing and operation. Herein we report the unprecedented stabilization effect of hindered amine light stabilizer (HALS) on methylammonium iodide (MAI) and MAPI against photooxidation. We found that HALS prevents the degradation of MAI by inhibiting the oxidation of iodide to iodine. Chemical modification of HALS allows us to incorporate it in MAPI films which extends the resistivity of MAPI against photodegradation at ambient air from a couple of hours to several days, while causing no significant changes in key properties, such as optical absorption and charge transport. These results represent an important advance in the fight against MAPI decomposition and demonstrate for the first time that antioxidants improve the stability of MAPI.
      PubDate: 2017-08-01T06:22:03.273079-05:
      DOI: 10.1002/cssc.201700707
       
  • Broadband Emitting 2D-Hybrid Organic Inorganic Perovskite Based on
           Cyclohexane-bis(methylamonium) Cation
    • Authors: Ishita neogi; Annalisa Bruno, Damodaran Bahulayan, Teck Wee Goh, Biplab Ghosh, Rakesh Ganguly, Daniele Cortecchia, Tze Chien Sum, Cesare Soci, Nripan Mathews, Subodh Gautam Mhaisalkar
      Abstract: A novel broadband emitting 2D-hybrid organic inorganic perovskite (CyBMA)PbBr4 based on highly flexible cis-1,3-bis(methylaminohydrobromide)cyclohexane (CyBMABr) core has been designed, synthesized and investigated, highlighting the effects of stereoisomerism of the templating cation on the formation and properties of the resulting perovskite. The new 2D-material has high exciton binding energy of 340 meV and a broad emission spanning from 380-750 nm, incorporating a prominent excitonic band and a less intense broad peak at room temperature. Prominent changes in the photoluminescence spectrum were observed at lower temperatures, showing remarkable enhancement in the intensity of broad band at the cost of excitonic emission. Temperature dependent PL mapping indicate the effective role of only a narrow band of excitonic absorption in the generation of the active channel for emission. Based on the evidences obtained from the photo-physical investigations, we attributed the evolution of the broad B-band of (CyBMA)PbBr4 to excitonic self-trapped states
      PubDate: 2017-07-28T00:55:49.501421-05:
      DOI: 10.1002/cssc.201701227
       
  • Carbon dioxide capture by aqueous ionic liquid solutions
    • Authors: Jairton Dupont; Nathalia M. Simon, Marcileia Zanatta, Francisco P. dos Santos, Marta C. Corvo, Eurico J. Cabrita
      Abstract: Confined water in aqueous solutions of imidazolium-based ionic liquids (ILs) associated with acetate and imidazolate anions react reversibly with CO2 to yield bicarbonate. Three types of CO2 sorption in these "IL-aqueous solutions" were observed: physical, CO2-imidazolium adduct generation and bicarbonate formation (up to 1.9 mol of bicarbonate/mol of IL), resulting in a 10/1 mol/mol total absorption of CO2 relative to imidazolate anions in the presence of water 1/1000 (IL/water). These sorption values are higher than the classical alkanol amines or even alkaline aqueous solutions under similar experimental conditions.
      PubDate: 2017-07-25T09:26:07.257338-05:
      DOI: 10.1002/cssc.201701044
       
  • Towards extending solar cells life time : Addition of a fluorous cation to
           triple-cation based perovskite films
    • Authors: Manuel Salado; M Asunción Fernández, Juan P Holgado, Samrana Kazim, M. K. Nazeeruddin, P J Dyson, Shahzada Ahmad
      Abstract: Organo metal halide perovskites have emerged as highly promising replacements for thin film solar cells. However, their poor stability under ambient conditions remains problematic, hindering commercial exploitation. Here, we describe our investigation on the incorporation of a fluorous-functionalized imidazolium cation in a highly stable cesium based mixed perovskite material (Cs0.05(MA0.15FA0.85)0.95Pb(I0.85Br0.15)3 and how it influnce enhances stability. The resulting materials, which vary according to the content of the fluorous-functionalized imidazolium cation, display a prolonged tolerance to atmospheric humidity (>100 days) along with power conversion efficiencies exceeding 16%. This work provides a general route which can be implemented in variety of perovskites and highlights a promising way to increase perovskite solar cell stability.
      PubDate: 2017-07-25T04:20:28.148225-05:
      DOI: 10.1002/cssc.201700797
       
  • Impact of Interfacial Layers in Perovskite Solar Cells
    • Authors: An-Na Cho; Nam-Gyu Park
      Abstract: Perovskite solar cell (PCSs) is composed of organic-inorganic lead halide perovskite as light harvester. Since the first report on long-term durable 9.7% efficient solid-state perovskite solar cell in 2012, organic-inorganic halide perovskite received great attention because of its superb opto-electronic properties. As a result, a power conversion efficiency (PCE) exceeding 22% was certified. Controlling grain size and grain boundary of perovskite layer perovskite is important for attaining high efficiency. In addition, interfacial engineering is equally or more important to improve further PCE via better charge collection and reduction in charge recombination. In this article, type of interfacial layers and their impacts on photovoltaic performance are investigated for the normal and inverted architectures. Grain boundary engineering is also included because it is related to interfacial engineering and grain boundary in perovskite layer plays important role in charge conduction, recombination and carrier life time.
      PubDate: 2017-07-23T21:30:22.262051-05:
      DOI: 10.1002/cssc.201701095
       
  • Low dimensional organic-inorganic halide perovskite: structure,
           properties, and applications
    • Authors: Ravi K.Misra; Bat-El Cohen, Lior Iagher, Lioz Etgar
      Abstract: Three-dimensional (3D) perovskite has attracted a lot of attention due to its success in photovoltaic (PV) solar cells. However, one the major crucial issues lies in its stability, which has limited its commercialization. An important property of organic-inorganic perovskite is the possibility of forming a layered material using long organic cations that do not fit into the octahedral cage. The long organic cation acts as a "barrier" that "caps" the 3D perovskite forming the layered material. Controlling the number of perovskite layers could provide a confined structure with different chemical and physical properties than 3D perovskite has. This opens up a whole new batch of interesting materials with huge potential for optoelectronic applications. This mini review presents the synthesis, properties, and structural orientation of low-dimensional perovskite. It also discusses the progress of low-dimensional perovskite in PV solar cells, which, to date, have a comparable performance but with enhanced stability in comparison with the 3D perovskite. Finally, the use of low-dimensional perovskite in LEDs and photodetectors is discussed. The low-dimensional perovskites are promising candidates for LED devices, mainly due to their high radiative recombination as a result of the confined low-dimensional quantum well.
      PubDate: 2017-07-13T10:25:26.032361-05:
      DOI: 10.1002/cssc.201701026
       
  • Cooking with active oxygen and solid alkali (CAOSA): a promising
           alternative approach for lignocellulosic biorefineries
    • Authors: Yetao Jiang; Xianhai Zeng, Rafael Luque, Xing Tang, Yong Sun, Tingzhou Lei, Shijie Liu, Lu Lin
      Abstract: Lignocellulosic biomass, a matrix of the biopolymers including cellulose, hemicellulose and lignin, has gathered increasing attention in recent years in the production of chemicals, fuels and materials based on biorefinery processes due to its renewability and availability. Fractionating lignocellulose is considered as the foundational step to establish an economical and sustainable lignocellulosic biorefinery. This Minireview summarized a newly developed oxygen delignification for lignocellulose fractionation called cooking with active oxygen and solid alkali (CAOSA), which could fractionate lignocellulose into its constituents while remaining in processable form. In the CAOSA approach, environmentally-friendly chemicals were applied instead of undesirable chemicals including strong alkalis and sulfides. Notably, the alkali recovery for this process promised to be relatively simple, neither causticizing nor sintering. These features made the CAOSA process an alternative for both lignocellulose fractionation and biomass pretreatment. Advantages and challenges have also been discussed in order to provide a comprehensive perspective with respect to existing strategies.
      PubDate: 2017-07-10T06:15:22.111817-05:
      DOI: 10.1002/cssc.201700906
       
  • Influence of the Water Phase State on the Thermodynamics of Aqueous Phase
           Reforming for Hydrogen Production
    • Authors: Séverine Le Gac; Renée M Ripken, Jan Meuldijk, Johannes G.E. Gardeniers
      Abstract: Abstract: Hydrogen is a promising renewable energy source that can be produced from biomass using Aqueous Phase Reforming (APR). Here, using data obtained from AspenPlus and the literature, we evaluated the phase state, temperature-dependent enthalpy, and Gibbs free energy for the APR of small biomass model substrates. Phase equilibrium studies reveal that, under typical APR reaction conditions, the reaction mixture is in the liquid phase. Therefore, we show for the first time that the water-gas-shift (WGS), which is the second main reaction of APR, must be modeled in the liquid phase, resulting in an endothermic instead of an exothermic enthalpy of reaction. A significant implication of this finding is that, although APR has been introduced as more energy saving than conventional reforming methods, the WGS in APR has a comparable energy demand to the WGS in steam reforming (SR).
      PubDate: 2017-07-10T04:15:42.924986-05:
      DOI: 10.1002/cssc.201700189
       
  • High Efficiency MAPbI3 Perovskite Solar Cell Using a Pure Thin Film of
           Polyoxometalate as Scaffold Layer
    • Authors: Mohammad Khaledi Sardashti; Mahmoud Zendehdel, Narges Yaghoobi Nia, Davud Karimian, Mohammad Sheikhi
      Abstract: In this work, we successfully used a pure layer of [SiW11O39]8- polyoxomethalate (POM) structure as a thin film scaffold layer of CH3NH3PbI3 based perovskite solar cells (PSCs). A smooth nanoporous surface of POM cause to amazing improvement of the photocurrent density, External Quantum Efficiency (EQE) and overall efficiency of the PSCs compare to mp-TiO2 as scaffold layer. Average PCE values of 15.5% with champion device as 16.3% could achieve by using POM and sequential deposition method of perovskite layer. Furthermore, modified and defect-free POM/perovskite interface led to elimination of the anomalous hysteresis in the current-voltage curves. Open-circuit voltage decay study show promising decrease of the electron recombination in the POM based PSCs which also related to modification of POM/perovskite interface and higher electron transport inside the POM layer.
      PubDate: 2017-07-07T23:25:56.281131-05:
      DOI: 10.1002/cssc.201701027
       
  • Prospective Symbiosis of Green Chemistry and Energetic Materials
    • Authors: Ilya V. Kuchurov; Mikhail N. Zharkov, Leonid L. Fershtat, Nina N. Makhova, Sergei G. Zlotin
      Abstract: A global increase in the environmental pollution demands the development of new "cleaner" chemical processes. Among urgent improvements, replacement of traditional hydrocarbon-derived toxic organic solvents with neoteric solvents less harmful for the environment is one of the most vital issues. Due to favorable combination of unique properties, ionic liquids (ILs), dense gases, and supercritical fluids (SCFs) have gained considered attention as suitable green chemistry media for preparation and modification of important chemical compounds and materials. In particular, they have a significant potential in a specific and very important area of research which is associated with manufacturing and processing of high-energy materials (HEMs). These large-scale manufacturing processes, in which hazardous chemicals and extreme conditions are used, produce a huge amount of hard-to-dispose waste. Furthermore, they are risky to staff and any improvements that would reduce fire and explosion risks of the corresponding processes are highly desirable. In this review, useful applications of almost non-flammable ILs, dense gases, and SCFs (first of all, carbon dioxide) for nitration and other reactions used for manufacturing of HEMs are considered. Recent advances in the field of energetic (oxygen-balanced and hypergolic) ILs are summarized. A significant attention is paid to the SCF-based micronization techniques, which improve energetic performance of HEMs via an efficient control of morphology and particle size distribution of the HEMs fine particles, and to useful applications of SCFs in HEM processing which makes them less hazardous.
      PubDate: 2017-07-06T09:20:30.114555-05:
      DOI: 10.1002/cssc.201701053
       
  • Hierarchical Hollow Covalent Organic Frameworks-derived Heteroatom-doped
           Carbon Spheres for Metal-free Catalysis
    • Authors: Liuyi Li; Lu Li, Caiyan Cui, Hongjun Fan, Ruihu Wang
      Abstract: Covalent organic frameworks (COFs) with hollow structures hold great promises for developing new types of functional materials. Herein, we report a hollow spherical COF with a hierarchical shell, which serves as an effective precursor of B,N-codoped hierarchical hollow carbon spheres. Benefiting from the synergistic effect of hierarchical porosity, high surface area and B,N-codoping, the as-synthesized carbon spheres show the prospective utility as metal-free catalysts in nitroarene reduction. A mechanistic hypothesis is proposed based on theoretical and experimental studies. B atoms meta to pyridinic N atoms are identified to be the main catalytic active sites. The anti-aromaticity originated from the codoping of B and pyridinic N atoms, not charge distribution and deformation energy, is corroborated to play a pivotal role in the catalytic reaction.
      PubDate: 2017-06-29T22:07:51.523633-05:
      DOI: 10.1002/cssc.201700979
       
  • Sustainable separations of C4 hydrocarbons using microporous materials
    • Authors: Stefania Tanase-Grecea; Mascha Gehre, Zhiyong Guo, Gadi Rothenberg
      Abstract: Petrochemical refineries must separate hydrocarbons mixtures on a large scale for the production of fuels and chemicals. Most often, these hydrocarbons are separated by distillation, which is extremely energy-intensive. This high energy cost can be mitigated by developing materials that can enable efficient adsorptive separation. In this critical review, we first outline the principles of adsorptive separation. We then examine the case for C4 separations using zeolites and metal-organic frameworks (MOFs). By analysing both experimental and theoretical studies, we outline the challenges and opportunities in C4 separation, with a focus on the separation mechanisms and structure-selectivity correlations. Zeolites are commonly used as adsorbents, and in some cases can separate C4 mixtures well. The pore sizes of 8-membered-ring zeolites, for example, are in the order of the kinetic diameters of C4 isomers. Although zeolites have the advantage of a rigid and highly stable structure, this is often difficult to functionalize. MOFs are attractive candidates for hydrocarbon separation because their pores can be tailored to optimize the adsorbate-adsorbent interactions. MOF-5 and ZIF-7 show promising results in separating all C4 isomers, but breakthrough experiments under industrial conditions are needed to confirm these results. Moreover, the flexibility of the MOF structures could hamper their application under industrial conditions. All in all, adsorptive separation is a promising viable alternative, and it is likely to play an increasingly important role in tomorrow's refineries.
      PubDate: 2017-06-15T21:20:27.077112-05:
      DOI: 10.1002/cssc.201700657
       
  • Boosting the supercapacitance of nitrogen-doped carbon by tuning surface
           functionalities
    • Authors: Jasper Biemolt; Ilse M. Denekamp, Thierry K. Slot, Gadi Rothenberg, David Eisenberg
      Abstract: We report that the specific capacitance of a highly porous, nitrogen-doped carbon is nearly tripled by orthogonal optimization of microstructure and surface chemistry. First, the carbons' hierarchical pore structure and specific surface area were tweaked by controlling the temperature and sequence of thermal treatments. The best process (pyrolysis at 900 °C, washing, and a second annealing at 1000 °C) yielded carbons with a specific capacitance of 117 F/g - nearly double that of a carbon made by a typical, single-step synthesis at 700 °C. Following the structural optimization, the surface chemistry of the carbons was enriched by applying an oxidation routine based on nitric and sulfuric acids in 1:4 ratio, at two different treatment temperatures (0 °C and 20 °C) and along different treatment times. The optimal treatment times are 4 h at 0 °C and only 1 h at 20 °C. Overall, specific capacitance nearly tripled relative to the original carbon, reaching to 168 F/g. The inherent nitrogen doping of the carbon comes into interplay with the acid-induced surface functionalization, creating a mixture of oxygen- and nitrogen-oxygen functionalities. The evolution of surface chemistry was carefully followed by X-ray photoelectron spectroscopy and by N2 sorption porometry, revealing stepwise surface functionalization and simultaneous carbon etching. Overall, these processes are responsible for the peak-shaped capacitance trends in the carbons.
      PubDate: 2017-06-06T10:15:21.602775-05:
      DOI: 10.1002/cssc.201700902
       
  • Factors Influencing the Mechanical Properties of Formamidinium Lead
           Halides and Related Hybrid Perovskites
    • Authors: Shijing Sun; Furkan H. Isikgor, Zeyu Deng, Fengxia Wei, Gregor Kieslich, Paul D. Bristowe, Jianyong Ouyang, Anthony K. Cheetham
      Pages: 3740 - 3745
      Abstract: The mechanical properties of formamidinium lead halide perovskites (FAPbX3, X=Br or I) grown by inverse-temperature crystallization have been studied by nanoindentation. The measured Young's moduli (9.7–12.3 GPa) and hardnesses (0.36–0.45 GPa) indicate good mechanical flexibility and ductility. The effects of hydrogen bonding were evaluated by performing ab initio molecular dynamics on both formamidinium and methylammonium perovskites and calculating radial distribution functions. The structural and chemical factors influencing these properties are discussed by comparison with corresponding values in the literature for other hybrid perovskites, including double perovskites. Our results reveal that bonding in the inorganic framework and hydrogen bonding play important roles in determining elastic stiffness. The influence of the organic cation becomes more important for structures at the limit of their perovskite stability, indicated by high tolerance factors.Hard or soft' Nanoindentation on single crystals of FAPbX3 (X=Br or I) is used to study the mechanical properties of formamidinium lead halide perovskites. The effects of hydrogen bonding are evaluated by ab initio molecular dynamics and calculating radial distribution functions.
      PubDate: 2017-07-26T06:16:07.06276-05:0
      DOI: 10.1002/cssc.201700991
       
  • Plasmonic Gold Nanostars Incorporated into High-Efficiency Perovskite
           Solar Cells
    • Authors: Munkhbayar Batmunkh; Thomas J. Macdonald, William J. Peveler, Abdulaziz S. R. Bati, Claire J. Carmalt, Ivan P. Parkin, Joseph G. Shapter
      Pages: 3750 - 3753
      Abstract: Incorporating appropriate plasmonic nanostructures into photovoltaic (PV) systems is of great utility for enhancing photon absorption and thus improving device performance. Herein, the successful integration of plasmonic gold nanostars (AuNSs) into mesoporous TiO2 photoelectrodes for perovskite solar cells (PSCs) is reported. The PSCs fabricated with TiO2-AuNSs photoelectrodes exhibited a device efficiency of up to 17.72 %, whereas the control cells without AuNSs showed a maximum efficiency of 15.19 %. We attribute the origin of increased device performance to enhanced light absorption and suppressed charge recombination.Golden star: Plasmonic gold nanostars are incorporated into mesoporous TiO2 photoelectrodes to fabricate high efficiency perovskite solar cells. A power conversion efficiency of 17.72 % is achieved using TiO2-AuNSs photoelectrode-based device.
      PubDate: 2017-08-03T07:05:27.258965-05:
      DOI: 10.1002/cssc.201701056
       
  • Photovoltaic Rudorffites: Lead-Free Silver Bismuth Halides Alternative to
           Hybrid Lead Halide Perovskites
    • Authors: Ivan Turkevych; Said Kazaoui, Eisuke Ito, Toshiyuki Urano, Koji Yamada, Hiroshi Tomiyasu, Hideo Yamagishi, Michio Kondo, Shinji Aramaki
      Pages: 3754 - 3759
      Abstract: Hybrid CPbX3 (C: Cs, CH3NH3; X: Br, I) perovskites possess excellent photovoltaic properties but are highly toxic, which hinders their practical application. Unfortunately, all Pb-free alternatives based on Sn and Ge are extremely unstable. Although stable and non-toxic C2ABX6 double perovskites based on alternating corner-shared AX6 and BX6 octahedra (A=Ag, Cu; B=Bi, Sb) are possible, they have indirect and wide band gaps of over 2 eV. However, is it necessary to keep the corner-shared perovskite structure to retain good photovoltaic properties' Here, we demonstrate another family of photovoltaic halides based on edge-shared AX6 and BX6 octahedra with the general formula AaBbXx (x=a+3 b) such as Ag3BiI6, Ag2BiI5, AgBiI4, AgBi2I7. As perovskites were named after their prototype oxide CaTiO3 discovered by Lev Perovski, we propose to name these new ABX halides as rudorffites after Walter Rüdorff, who discovered their prototype oxide NaVO2. We studied structural and optoelectronic properties of several highly stable and promising Ag–Bi–I photovoltaic rudorffites that feature direct band gaps in the range of 1.79–1.83 eV and demonstrated a proof-of-concept FTO/c-m-TiO2/Ag3BiI6/PTAA/Au (FTO: fluorine-doped tin oxide, PTAA: poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], c: compact, m: mesoporous) solar cell with photoconversion efficiency of 4.3 %.Move over perovskite: Optoelectronic properties of several highly stable silver iodobismuthates with rudorffite structure reveal them as alternative nontoxic and solution-processable photovoltaic materials that feature direct band gaps of around 1.8 eV. The proof-of-concept solar cell with FTO/c-m-TiO2/Ag3BiI6/PTAA/Au (c: compact; m: mesoporous; PTAA: poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]) architecture shows a promising power conversion efficiency of 4.3 %.
      PubDate: 2017-07-06T05:35:41.090549-05:
      DOI: 10.1002/cssc.201700980
       
  • Low-Cost Perovskite Solar Cells Employing
           Dimethoxydiphenylamine-Substituted Bistricyclic Aromatic Enes as Hole
           Transport Materials
    • Authors: Kasparas Rakstys; Sanghyun Paek, Giulia Grancini, Peng Gao, Vygintas Jankauskas, Abdullah M. Asiri, Mohammad Khaja Nazeeruddin
      Pages: 3825 - 3832
      Abstract: The synthesis, characterization and photovoltaic performance of series of novel molecular hole transport materials (HTMs) based on bistricyclic aromatic enes (BAEs) are presented. The new derivatives were obtained following a simple and straightforward procedure from inexpensive starting reagents mimicking the synthetically challenging 9,9′-spirobifluorene moiety of the well-studied spiro-OMeTAD. The novel HTMs were tested in mixed cations and anions perovskite solar cells (PSCs) yielding a power conversion efficiency (PCE) of 19.2 % under standard global 100 mW cm−2 AM1.5G illumination using 9-{2,7-bis[bis(4-methoxyphenyl)amino]-9H-fluoren-9-ylidene}-N2,N2,N7,N7-tetrakis(4-methoxyphenyl)-9H-thioxanthene-2,7-diamine (coded as KR374). The power conversion efficiency data confirms the easily attainable heteromerous fluorenylidenethioxanthene structure as valuable core for low-cost and highly efficient HTM design and paves the way towards cost-effective PSC technology.Bridge to success: We report the synthesis of three new hole transport materials (HTMs) using a cost-effective procedure and the impact of different atoms in heteromerous bistricyclic aromatic ene scaffolds. S-bridged KR374 shows a a significantly improved hole-drift mobility leading to enhanced photovoltaic performance in mixed-ion perovskite solar cells and reduced hysteresis owing to the improved interface between the perovskite and HTM caused by stronger Pb–S interaction.
      PubDate: 2017-08-03T07:10:42.610341-05:
      DOI: 10.1002/cssc.201700974
       
  • Replacement of Biphenyl by Bipyridine Enabling Powerful Hole Transport
           Materials for Efficient Perovskite Solar Cells
    • Authors: Fei Wu; Yahan Shan, Jianhui Qiao, Cheng Zhong, Rui Wang, Qunliang Song, Linna Zhu
      Pages: 3833 - 3838
      Abstract: Here, 2,2′- and 3,3′-bipyridine are introduced for the first time as the core structure to get two new hole transport materials (HTMs), namely F22 and F33. The electron-withdrawing nature of bipyridine lowers the HOMO level of the new compounds and enhances the open-circuit voltage of perovskite solar cells. Especially for F33, the better planarity leads to better conjugation in the whole molecule and the molecular interaction is enhanced. Hole-mobility tests, steady-state photoluminescence (PL) spectra as well as time-resolved PL decay results demonstrate that the new HTMs exhibit good hole extraction and hole-transporting property. Impressive power conversion efficiencies of 17.71 and 18.48 % are achieved in conventional planar perovskite (CH3NH3PbI3−xClx) solar cells containing F22 and F33 as HTMs, respectively. As far as we know, this is the first report on bypiridine-based HTMs with leading efficiencies, and the design motif in this work opens a new way for devising HTMs in the future.Bip, bip: Bipyridine is introduced for the first time as the core structure for new hole transport materials (HTMs). Remarkable power conversion efficiencies of 17.71 and 18.48 % are achieved in conventional planar perovskite (CH3NH3PbI3−xClx) solar cells by using the newly devised HTMs.
      PubDate: 2017-08-02T06:11:24.644054-05:
      DOI: 10.1002/cssc.201700973
       
  • Molecular Self-Assembly Fabrication and Carrier Dynamics of Stable and
           Efficient CH3NH3Pb(1−x)SnxI3 Perovskite Solar Cells
    • Authors: Jiandong Fan; Chong Liu, Hongliang Li, Cuiling Zhang, Wenzhe Li, Yaohua Mai
      Pages: 3839 - 3845
      Abstract: The Sn-based perovskite solar cells (PSCs) provide the possibility of swapping the Pb element toward developing toxic-free PSCs. Here, we innovatively employed a molecular self-assembly approach to obtain a series CH3NH3Pb(1−x)SnxI3 (0≤x≤1) perovskite thin films with full coverage. The optimized planar CH3NH3Pb0.75Sn0.25I3 PSC with inverted structure was consequently realized with a maximum power conversion efficiency (PCE) over 14 %, which displayed a stabilized power output (SPO) over 12 % within 200 s at 0.6 V forward bias. Afterward, we investigated the factors that limited the efficiency improvement of hybrid Sn–Pb PSCs, and analyzed the possible reason of the hysteresis effect occurred even in the inverted structure cell. Particularly, the oxidation of hybrid Sn–Pb perovskite thin film was demonstrated to be the main reason that limited its further efficiency improvement. The imbalance of charge transport was intensified, which was associated with the increased hole defect-state density and decreased electron defect-state density after Sn was introduced. This study helps tackle the intractable issue regarding the toxic Pb in perovskite devices and is a step forward toward realizing lead-free PSCs with high stability and efficiency.Toward lead-free: We employ a molecular self-assembly approach to obtain a series CH3NH3Pb(1−x)SnxI3 (0≤x≤1) perovskite with high stability and efficiency. The reasons that limit its further efficiency improvement are provided by means of studying the carrier dynamics in the device.
      PubDate: 2017-08-04T05:00:28.995181-05:
      DOI: 10.1002/cssc.201700880
       
  • High-Efficiency Perovskite Solar Cell Based on Poly(3-Hexylthiophene):
           Influence of Molecular Weight and Mesoscopic Scaffold Layer
    • Authors: Narges Yaghoobi Nia; Fabio Matteocci, Lucio Cina, Aldo Di Carlo
      Pages: 3854 - 3860
      Abstract: Here, we investigated the effect of the molecular weight (MW) of poly 3-hexylthiophene (P3HT) hole-transport material on the performance of perovskite solar cells (PSCs). We found that by increasing the MW the photovoltaic performances of the cells are enhanced leading to an improvement of the overall efficiency. P3HT-based PSCs with a MW of 124 kDa can achieve an overall average efficiency of 16.2 %, double with respect to the ones with a MW of 44 kDa. Opposite to spiro-OMeTAD-based PSCs, the photovoltaic parameters of the P3HT-based devices are enhanced by increasing the mesoporous TiO2 layer thickness from 250 to 500 nm. Moreover, for a titania scaffold layer thickness of 500 nm, the efficiency of P3HT-based PSCs with high MW is larger than the spiro-OMeTAD based PSCs with the same scaffold layer thickness. Recombination reactions of the devices were also investigated by voltage decay and electrochemical impedance spectroscopy. We found that the relationship between P3HT MW and cell performance is related to the reduction of charge recombination and to the increase of the P3HT light absorption by increasing the MW.Molecular weight matters! High efficiency perovskite solar cells fabricated in ambient conditions by controlling of mesoporous (mp)-TiO2 thickness and investigation of poly(3-hexylthiophene) (P3HT) molecular weight (MW) as hole-transport layer. The best efficiencies are achieved for a MW of 124 kDa and for a thickness of mp-TiO2 of 500 nm. Efficiency enhancement is mainly related to the increase of Jsc and FF as P3HT MW increases.
      PubDate: 2017-06-14T15:31:37.454372-05:
      DOI: 10.1002/cssc.201700635
       
 
 
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