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  Subjects -> COMPUTER SCIENCE (Total: 1991 journals)
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COMPUTER SCIENCE (1157 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 872 Journals sorted alphabetically
3D Printing and Additive Manufacturing     Full-text available via subscription   (Followers: 13)
Abakós     Open Access   (Followers: 4)
ACM Computing Surveys     Hybrid Journal   (Followers: 23)
ACM Journal on Computing and Cultural Heritage     Hybrid Journal   (Followers: 9)
ACM Journal on Emerging Technologies in Computing Systems     Hybrid Journal   (Followers: 13)
ACM Transactions on Accessible Computing (TACCESS)     Hybrid Journal   (Followers: 3)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 16)
ACM Transactions on Applied Perception (TAP)     Hybrid Journal   (Followers: 6)
ACM Transactions on Architecture and Code Optimization (TACO)     Hybrid Journal   (Followers: 9)
ACM Transactions on Autonomous and Adaptive Systems (TAAS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Computation Theory (TOCT)     Hybrid Journal   (Followers: 12)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 4)
ACM Transactions on Computer Systems (TOCS)     Hybrid Journal   (Followers: 18)
ACM Transactions on Computer-Human Interaction     Hybrid Journal   (Followers: 14)
ACM Transactions on Computing Education (TOCE)     Hybrid Journal   (Followers: 5)
ACM Transactions on Design Automation of Electronic Systems (TODAES)     Hybrid Journal   (Followers: 1)
ACM Transactions on Economics and Computation     Hybrid Journal  
ACM Transactions on Embedded Computing Systems (TECS)     Hybrid Journal   (Followers: 4)
ACM Transactions on Information Systems (TOIS)     Hybrid Journal   (Followers: 21)
ACM Transactions on Intelligent Systems and Technology (TIST)     Hybrid Journal   (Followers: 8)
ACM Transactions on Interactive Intelligent Systems (TiiS)     Hybrid Journal   (Followers: 3)
ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP)     Hybrid Journal   (Followers: 10)
ACM Transactions on Reconfigurable Technology and Systems (TRETS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Sensor Networks (TOSN)     Hybrid Journal   (Followers: 9)
ACM Transactions on Speech and Language Processing (TSLP)     Hybrid Journal   (Followers: 11)
ACM Transactions on Storage     Hybrid Journal  
ACS Applied Materials & Interfaces     Full-text available via subscription   (Followers: 25)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Ad Hoc Networks     Hybrid Journal   (Followers: 11)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Advanced Engineering Materials     Hybrid Journal   (Followers: 26)
Advanced Science Letters     Full-text available via subscription   (Followers: 8)
Advances in Adaptive Data Analysis     Hybrid Journal   (Followers: 8)
Advances in Artificial Intelligence     Open Access   (Followers: 16)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 15)
Advances in Computer Science : an International Journal     Open Access   (Followers: 14)
Advances in Computing     Open Access   (Followers: 2)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 51)
Advances in Engineering Software     Hybrid Journal   (Followers: 26)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Human-Computer Interaction     Open Access   (Followers: 20)
Advances in Materials Sciences     Open Access   (Followers: 16)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 38)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Advances in Technology Innovation     Open Access   (Followers: 2)
AEU - International Journal of Electronics and Communications     Hybrid Journal   (Followers: 8)
African Journal of Information and Communication     Open Access   (Followers: 8)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 4)
Air, Soil & Water Research     Open Access   (Followers: 9)
AIS Transactions on Human-Computer Interaction     Open Access   (Followers: 6)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1)
Algorithms     Open Access   (Followers: 11)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 4)
American Journal of Computational Mathematics     Open Access   (Followers: 4)
American Journal of Information Systems     Open Access   (Followers: 7)
American Journal of Sensor Technology     Open Access   (Followers: 4)
Anais da Academia Brasileira de Ciências     Open Access   (Followers: 2)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 7)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Animation Practice, Process & Production     Hybrid Journal   (Followers: 5)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Data Science     Hybrid Journal   (Followers: 11)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 7)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Software Engineering     Hybrid Journal   (Followers: 13)
Annual Reviews in Control     Hybrid Journal   (Followers: 6)
Anuario Americanista Europeo     Open Access  
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applied and Computational Harmonic Analysis     Full-text available via subscription   (Followers: 2)
Applied Artificial Intelligence: An International Journal     Hybrid Journal   (Followers: 14)
Applied Categorical Structures     Hybrid Journal   (Followers: 2)
Applied Clinical Informatics     Hybrid Journal   (Followers: 2)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Computer Systems     Open Access   (Followers: 1)
Applied Informatics     Open Access  
Applied Mathematics and Computation     Hybrid Journal   (Followers: 33)
Applied Medical Informatics     Open Access   (Followers: 11)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Soft Computing     Hybrid Journal   (Followers: 16)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Architectural Theory Review     Hybrid Journal   (Followers: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 5)
Archive of Numerical Software     Open Access  
Archives and Museum Informatics     Hybrid Journal   (Followers: 131)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Artifact     Hybrid Journal   (Followers: 2)
Artificial Life     Hybrid Journal   (Followers: 6)
Asia Pacific Journal on Computational Engineering     Open Access  
Asia-Pacific Journal of Information Technology and Multimedia     Open Access   (Followers: 1)
Asian Journal of Computer Science and Information Technology     Open Access  
Asian Journal of Control     Hybrid Journal  
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
Australian Educational Computing     Open Access   (Followers: 1)
Automatic Control and Computer Sciences     Hybrid Journal   (Followers: 4)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Automatica     Hybrid Journal   (Followers: 11)
Automation in Construction     Hybrid Journal   (Followers: 6)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Basin Research     Hybrid Journal   (Followers: 5)
Behaviour & Information Technology     Hybrid Journal   (Followers: 52)
Bioinformatics     Hybrid Journal   (Followers: 307)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 32)
Briefings in Bioinformatics     Hybrid Journal   (Followers: 44)
British Journal of Educational Technology     Hybrid Journal   (Followers: 129)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
c't Magazin fuer Computertechnik     Full-text available via subscription   (Followers: 2)
CALCOLO     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Journal of Electrical and Computer Engineering     Full-text available via subscription   (Followers: 14)
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal  
Cell Communication and Signaling     Open Access   (Followers: 1)
Central European Journal of Computer Science     Hybrid Journal   (Followers: 5)
CERN IdeaSquare Journal of Experimental Innovation     Open Access  
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
ChemSusChem     Hybrid Journal   (Followers: 7)
China Communications     Full-text available via subscription   (Followers: 7)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
CIN Computers Informatics Nursing     Full-text available via subscription   (Followers: 12)
Circuits and Systems     Open Access   (Followers: 16)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
CLEI Electronic Journal     Open Access  
Clin-Alert     Hybrid Journal   (Followers: 1)
Cluster Computing     Hybrid Journal   (Followers: 1)
Cognitive Computation     Hybrid Journal   (Followers: 4)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Communication Methods and Measures     Hybrid Journal   (Followers: 12)
Communication Theory     Hybrid Journal   (Followers: 20)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Algebra     Hybrid Journal   (Followers: 3)
Communications in Partial Differential Equations     Hybrid Journal   (Followers: 3)
Communications of the ACM     Full-text available via subscription   (Followers: 53)
Communications of the Association for Information Systems     Open Access   (Followers: 18)
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering     Hybrid Journal   (Followers: 3)
Complex & Intelligent Systems     Open Access  
Complex Adaptive Systems Modeling     Open Access  
Complex Analysis and Operator Theory     Hybrid Journal   (Followers: 2)
Complexity     Hybrid Journal   (Followers: 6)
Complexus     Full-text available via subscription  
Composite Materials Series     Full-text available via subscription   (Followers: 9)
Computación y Sistemas     Open Access  
Computation     Open Access  
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 and Structural Biotechnology Journal     Open Access   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Astrophysics and Cosmology     Open Access   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Computational Chemistry     Open Access   (Followers: 2)
Computational Cognitive Science     Open Access   (Followers: 2)
Computational Complexity     Hybrid Journal   (Followers: 4)
Computational Condensed Matter     Open Access  
Computational Ecology and Software     Open Access   (Followers: 9)
Computational Economics     Hybrid Journal   (Followers: 9)
Computational Geosciences     Hybrid Journal   (Followers: 14)
Computational Linguistics     Open Access   (Followers: 23)
Computational Management Science     Hybrid Journal  
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 4)
Computational Methods and Function Theory     Hybrid Journal  
Computational Molecular Bioscience     Open Access   (Followers: 2)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Particle Mechanics     Hybrid Journal   (Followers: 1)
Computational Research     Open Access   (Followers: 1)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computational Science and Techniques     Open Access  
Computational Statistics     Hybrid Journal   (Followers: 13)
Computational Statistics & Data Analysis     Hybrid Journal   (Followers: 31)
Computer     Full-text available via subscription   (Followers: 87)
Computer Aided Surgery     Hybrid Journal   (Followers: 3)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 7)
Computer Communications     Hybrid Journal   (Followers: 10)
Computer Engineering and Applications Journal     Open Access   (Followers: 5)
Computer Journal     Hybrid Journal   (Followers: 8)
Computer Methods in Applied Mechanics and Engineering     Hybrid Journal   (Followers: 22)
Computer Methods in Biomechanics and Biomedical Engineering     Hybrid Journal   (Followers: 10)
Computer Methods in the Geosciences     Full-text available via subscription   (Followers: 1)
Computer Music Journal     Hybrid Journal   (Followers: 16)
Computer Physics Communications     Hybrid Journal   (Followers: 6)
Computer Science - Research and Development     Hybrid Journal   (Followers: 7)
Computer Science and Engineering     Open Access   (Followers: 17)
Computer Science and Information Technology     Open Access   (Followers: 12)
Computer Science Education     Hybrid Journal   (Followers: 13)
Computer Science Journal     Open Access   (Followers: 20)
Computer Science Master Research     Open Access   (Followers: 10)
Computer Science Review     Hybrid Journal   (Followers: 10)

        1 2 3 4 5 6 | 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]
  • Pyran-bridged indacenodithiophene: A novel building block for constructing
           efficient A-D-A type nonfullerene acceptor for polymer solar cells
    • Authors: Renqiang Yang; Shuguang Wen, Yao Wu, Yingying Wang, Yi Li, Ling Liu, Huanxiang Jiang, Zhitian Liu
      Abstract: In recent years, nonfullerene acceptors have attracted much attention due to their great potential for achieving high performance polymer solar cells. In this paper, a novel ladder type building block of pyran-bridged indacenodithiophene (PDT) has been designed for constructing A-D-A nonfullerene acceptors through introducing oxygen atoms into the commonly used indacenodithiophene (IDT) unit. The key step for the synthesis of PDT unit is accomplished by a BBr3-mediated tandem cyclization-deprotection reaction to construct the pyran-ring. In this approach, a novel molecular acceptor PTIC was successfully synthesized and applied in polymer solar cell device. Compared to the IDT-based acceptor, PTIC exhibits higher HOMO levels and wider optical bandgap at 550-800 nm. Polymer solar cells devices fabricated with PBDB-T:PTIC as active layer show a power conversion efficiency (PCE) of 7.66%. The introduction of oxygen atoms would be an effective approach for the modification of acceptor materials for polymer solar cells.
      PubDate: 2017-11-19T22:16:08.670735-05:
      DOI: 10.1002/cssc.201701917
       
  • Effect of Tetrahydrofuran on the Solubilisation and Depolymerisation of
           Cellulose in a Biphasic System
    • Authors: Changwei Hu; Zhicheng Jiang, Pingping Zhao, Jianmei Li, Xudong Liu
      Abstract: The dissolution of cellulose from biomass is a crucial but complicated issue for the utilisation of biomass resources, because of the extreme insolubility of cellulose. Herein, a biphasic NaCl-H2O-tetrahydrofuran system was studied, where most of the pure microcrystalline cellulose (M-cellulose, 96.6% conversion at 220 oC) and that contained in actual biomass were converted. Nearly a half of O(6)H***O(3) intermolecular hydrogen bonding could be broken by THF in H2O-THF co-solvent system, whereas the cleavage of O(2)H***O(6) intramolecular hydrogen bonding by H2O was significantly inhibited. In NaCl-H2O-THF system, THF could significantly promote the effects of both H2O and NaCl on the disruption of O(2)H***O(6) and O(3)H***O(5) intramolecular hydrogen bondings, respectively. In addition, THF could protect and transfer the cellulose-derived products to organic phase through forming hydrogen bonding between oxygen atom in THF and hydrogen atom of C4-O-H in glucose or aldehyde group in 5-hydroxymethylfurfural (HMF), which can lead more NaCl to combine with -OH of M-cellulose and further disrupt hydrogen bonds in M-cellulose, thereby improving the yield of small molecular weight products (especially HMF) and further promoting the dissolution of cellulose. As a cheap and reusable system, NaCl-H2O-THF system may be a promising approach for the dissolution and further conversion of cellulose in lignocellulosic biomass without any enzymes, ionic liquid nor conventional catalyst.
      PubDate: 2017-11-17T04:55:24.735051-05:
      DOI: 10.1002/cssc.201701861
       
  • 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, Dmitriy Shevela, Johannes Messinger, Philipp Kurz
      Abstract: The Cover Feature shows a new anode type for water-oxidation catalysis and its combination with the direct monitoring of gaseous reaction products by mass-spectrometry. Here, layered manganese oxides (birnessites) were directly deposited on carbon during reactions of permanganate with different—also nanostructured—carbon substrates. The highest and most stable water-oxidation currents were observed for birnessites on graphitic carbon where mass spectra confirmed high faradaic O2 yields. On the other hand, supports containing more sp3 carbon atoms corroded, leading to significant CO2 evolution. The good performance and low material cost of MnOx/Cgraphitic anodes makes them, for example, attractive components for light-driven water electrolysers. More information can be found in the Full Paper by Melder et al.
      PubDate: 2017-11-16T09:35:21.774781-05:
      DOI: 10.1002/cssc.201702129
       
  • Catalytic Transfer Hydrogenation of Biomass-Derived Carbonyls over
           Hafnium-Based Metal-Organic Frameworks
    • Authors: Avelino Corma; Pilar García-García, Sergio Rojas-Buzo
      Abstract: A series of highly crystalline, porous, hafnium-based metal-organic frameworks (MOFs) have shown to catalyze the transfer hydrogenation reaction of levulinic ester to produce γ-valerolactone using isopropanol as hydrogen donor and the results are compared with the zirconium-based counterparts. The role of the metal center in Hf-MOFs has been identified and reaction parameters optimized. NMR studies with isotopically labeled isopropanol evidences that the transfer hydrogenation occurs via a direct intermolecular hydrogen transfer route. The catalyst, Hf-MOF-808, can be recycled several times with only a minor decrease in catalytic activity. Generality of the procedure was shown by accomplishing the transformation with aldehydes, ketones and α,β-unsaturated carbonyl compounds. The combination of Hf-MOF-808 with the Brønsted acidic Al-Beta zeolite gives the four-step one-pot transformation of furfural to γ-valerolactone in good yield of 72%.
      PubDate: 2017-11-15T06:50:23.736792-05:
      DOI: 10.1002/cssc.201701708
       
  • Quantum Chemical Modeling of Homogeneous Water Oxidation Catalysis
    • Authors: Rong-Zhen Liao; Per E. M. Siegbahn
      Abstract: The Cover Feature shows transition-metal-catalyzed oxygen evolution by water oxidation with the liberation of protons and electrons. Density functional calculations can be used to elucidate the catalytic mechanism, calculate pKas and redox potentials, and construct full energy diagram for the whole catalytic cycle. More information can be found in the Review by Liao and Siegbahn.
      PubDate: 2017-11-14T12:46:08.081356-05:
      DOI: 10.1002/cssc.201702128
       
  • Metal Phosphides as Co-Catalysts for Photocatalytic and
           Photoelectrocatalytic Water Splitting
    • Authors: Shuang Cao; Chuan-Jun Wang, Wen-Fu Fu, Yong Chen
      Abstract: Invited for this month′s cover is the group of Yong Chen and Wen-Fu Fu at the Technical Institute of Physics and Chemistry of Chinese Academy of Sciences. The image shows a series of transition metal phosphides act as co-catalysts for photocatalytic and photoelectrochemical water splitting. The Minireview itself is available at 10.1002/cssc.201701450.“Exploring and learning from nature plays an important role in scientific research…” 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.201701450. View the Front Cover here: 10.1002/cssc.201702126.
      PubDate: 2017-11-14T12:46:06.733488-05:
      DOI: 10.1002/cssc.201702127
       
  • Metal Phosphides as Co-Catalysts for Photocatalytic and
           Photoelectrocatalytic Water Splitting
    • Authors: Shuang Cao; Chuan-Jun Wang, Wen-Fu Fu, Yong Chen
      Abstract: The Front Cover shows a representation of a vast universe with a series of transition metal phosphides, which can be explored and used as photochemical and photoelectrochemical water-splitting co-catalysts. More information can be found in the Minireview by Cao et al.
      PubDate: 2017-11-14T12:45:58.497334-05:
      DOI: 10.1002/cssc.201702126
       
  • 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: The Cover Feature shows bio-inspired electrocatalysis for the oxygen evolution reaction on LiMn2O4 nanocrystals. The electrocatalyst shares the cubane motif with the active site of photosystem II and the valence of Mn3.5+ with the dark-stable state of natural photosynthesis. These commonalities allow discussion of the electrocatalytic mechanism of LiMn2O4 in the context of natural photosynthesis. More information can be found in the Full Paper by Köhler et al.
      PubDate: 2017-11-14T12:45:50.891497-05:
      DOI: 10.1002/cssc.201701810
       
  • Production of Jet Fuel-Range Hydrocarbons from Hydrodeoxygenation of
           Lignin over Super Lewis Acid Combined with Metal Catalysts
    • Authors: Hongliang Wang; Huamin Wang, Eric Kuhn, Melvin P. Tucker, Bin Yang
      Abstract: Super Lewis acids containing the triflate anion [e.g., Hf(OTf)4, Ln(OTf)3, In(OTf)3, Al(OTf)3] and noble metal catalysts (e.g., Ru/C, Ru/Al2O3) formed efficient catalytic systems to generate saturated hydrocarbons from lignin in high yields. In such catalytic systems, the metal triflates mediated rapid ether bond cleavage through selective bonding to etheric oxygens while the noble metal catalyzed subsequent hydrodeoxygenation (HDO) reactions. Near theoretical yields of hydrocarbons were produced from lignin model compounds by the combined catalysis of Hf(OTf)4 and ruthenium-based catalysts. When a technical lignin derived from a pilot-scale biorefinery was used, more than 30 wt % of the hydrocarbons produced with this catalytic system were cyclohexane and alkylcyclohexanes in the jet fuel range. Super Lewis acids are postulated to strongly interact with lignin substrates by protonating hydroxyl groups and ether linkages, forming intermediate species that enhance hydrogenation catalysis by supported noble metal catalysts. Meanwhile, the hydrogenation of aromatic rings by the noble metal catalysts can promote oxygenation reactions catalyzed by super Lewis acids.The biggest Lewiser: Super Lewis acids and noble metals form an efficient catalytic system that can overcome the energy barrier for conversion of lignin into high yield jet-fuel range hydrocarbons. Metal triflates mediate rapid ether bond cleavage through selective bonding to the etheric oxygen, whereas the noble metal catalyzes the subsequent hydrogenation reaction, eliminating functional groups.
      PubDate: 2017-11-14T12:45:22.716058-05:
      DOI: 10.1002/cssc.201701567
       
  • Role of bismuth in the electro-kinetics of silicon photocathodes for solar
           rechargeable vanadium redox flow batteries
    • Authors: Cristina Flox; Sebastián Murcia-López, Nina M. Carretero, Carles Ros, Juan Ramón Morante, Teresa Andreu
      Abstract: The ability of crystalline Si to photo-assist the V3+/V2+ cathodic reaction under simulated solar irradiation, combined with the effect of Bi have led to important electrochemical improvements. Besides the photo-voltage supplied by the photovoltaics, additional decrease in the onset potentials, high reversibility of the V3+/V2+ redox pair and improvement in the electro-kinetics have been attained thanks to the addition of Bi. In fact, Bi0 deposition has shown to slightly decrease the photocurrent, but the significant betterment in the charge transfer, reflected in the overall electrochemical performance clearly justifies its use as additive in a photo-assisted system for maximizing the efficiency of solar charge to battery.
      PubDate: 2017-11-14T09:51:00.424496-05:
      DOI: 10.1002/cssc.201701879
       
  • Corrigendum: Highly Active N,O Zinc Guanidine Catalysts for the
           Ring-Opening Polymerization of Lactide
    • Authors: Pascal M. Schäfer; Martin Fuchs, Andreas Ohligschläger, Ruth Rittinghaus, Paul McKeown, Enver Akin, Maximilian Schmidt, Alexander Hoffmann, Marcel A. Liauw, Matthew D. Jones, Sonja Herres-Pawlis
      PubDate: 2017-11-14T05:50:20.554383-05:
      DOI: 10.1002/cssc.201702066
       
  • Artificial Photosynthesis: Beyond Mimicking Nature
    • Authors: Holger Dau; Etsuko Fujita, Licheng Sun
      Abstract: In this Editorial, Guest Editors Holger Dau, Etsuko Fujita, and Licheng Sun introduce the Special Issue of ChemSusChem on “Artificial Photosynthesis for Sustainable Fuels”. They discuss the need for non-fossil based fuels, introduce both biological and artificial photosynthesis, and outline various important concepts in artificial photosynthesis, including molecular and solid-state catalysts for water oxidation and hydrogen evolution, catalytic CO2 reduction, and photoelectrochemical systems.Here comes the sun: In this Editorial, Guest Editors Holger Dau, Etsuko Fujita, and Licheng Sun introduce the Special Issue of ChemSusChem on “Artificial Photosynthesis for Sustainable Fuels” and outline various important concepts in artificial photosynthesis, including water oxidation, hydrogen evolution, and CO2 reduction reactions with both molecular and heterogeneous catalysts.
      PubDate: 2017-11-13T05:02:56.175652-05:
      DOI: 10.1002/cssc.201702106
       
  • The three-dimensional-structure of twisted benzo[ghi]perylene-triimide
           dimer as a non-fullerene acceptor for inverted perovskite solar cells
    • Authors: Priyadharsini Karuppuswamy; Hung-Cheng Chen, Pen-Cheng Wang, Chao-Ping Hsu, Ken-Tsung Wong, Chih Wei Chu
      Abstract: In this work, we introduced benzo[ghi]perylenetriimide (BPTI) derivatives including monomer and twisted dimer (t-BPTI) as an alternative electron transport layer (ETL) material to replace the commonly used PC61BM in inverted planar heterojunction perovskite solar cells. Moreover, the double ETL layer was applied in our perovskite solar cells with structure of glass/ITO/PEDOT:PSS/perovskite/BPTI/C60 or PDI-C4/BCP/Al. Use of a double ETL layer structure can effectively eliminate the leakage current. The devices with the t-BPTI/C60 double ETL layer yield an average power conversion efficiency of 10.73% and a maximum efficiency of 11.63%. The device based on the complete non-fullerene electron acceptors of t-BPTI/PDI-C4 as double ETL achieved maximum efficiency of 10.0%. Besides, it is found that the utilization of alloy t-BPTI+BPTI as ETL can effectively reduce the hysteresis effect of perovskite solar cells. The results suggest that BPTI based electron transport materials are potential alternatives for widely used fullerene acceptors in PSCs.
      PubDate: 2017-11-12T22:45:24.902476-05:
      DOI: 10.1002/cssc.201701827
       
  • Ruthenium Ion-Complexed Graphitic Carbon Nitride Nanosheets Supported on
           Reduced Graphene Oxide as High-Performance Catalysts for Electrochemical
           Hydrogen Evolution
    • Authors: Shaowei Chen; Yi Peng, Wanzhang Pan, Nan Wang, Jia-En Lu
      Abstract: Carbon-based materials are promising, low-cost electrocatalysts toward hydrogen evolution reaction (HER), although the catalytic performance needs to be further improved before commercialization. In this study, ruthenium ions are incorporated into carbon nitride-reduced graphene oxide hybrids forming C3N4-rGO-Ru composites through RuN coordination. The incorporation of Ru ions, at a loading of 1.93 at.%, leads to electron redistribution within the materials and dramatically enhances the HER performance, as compared to C3N4, C3N4-rGO, and C3N4-Ru, with an overpotential of only 80 mV to reach the current density of 10 mA/cm2, a Tafel slope of 55 mV/dec, and an exchange current density of 0.462 mA/cm2. This performance is highly comparable to that of Pt/C, and ascribed to the positive shift of the conduction band of the composite, where the charge carrier density increases by over 200 times, as compared to that of C3N4, leading to a lower energy barrier of hydrogen evolution. The results suggest a new strategy in the design and engineering of functional nanocomposites for effective HER electrocatalysis by embedding select metal ions into the carbon-based molecular skeletons.
      PubDate: 2017-11-09T14:25:38.553431-05:
      DOI: 10.1002/cssc.201701880
       
  • Metal Phosphides as Co-Catalysts for Photocatalytic and
           Photoelectrocatalytic Water Splitting
    • Authors: Shuang Cao; Chuan-Jun Wang, Wen-Fu Fu, Yong Chen
      Abstract: Solar-to-hydrogen conversion based on photocatalytic and photoelectrocatalytic water splitting is considered as a promising technology for sustainable hydrogen production. Developing earth-abundant H2-production materials with robust activity and stability has become the mainstream in this field. Due to the unique properties and characteristics, transition metal phosphides (TMPs) have been proven to be high performance co-catalysts to replace some of the classic precious metal materials in photocatalytic water splitting. In this Minireview, we summarize the recent significant progress of TMPs as cocatalysts for water splitting reaction with high activity and stability. Firstly, the characteristic of TMPs is briefly introduced. Then, we mainly discuss the recent research efforts toward their application as photocatalytic co-catalysts in photocatalytic H2-production, O2-evolution and photoelectrochemical water splitting. Finally, the catalytic mechanism, current existing challenges and future working directions for improving the performance of TMPs are proposed.What's all the phos about' This Minireview concerns recent progress in metal phosphide-based heterogeneous photocatalysts for water splitting to produce high-purity hydrogen. Various systems with optimized or enhanced photocatalytic efficiency are introduced through specific examples. The possible catalytic mechanism, recent challenges, and future research directions for optimizing the performance of metal-phosphide-based co-catalysts are discussed.
      PubDate: 2017-11-09T12:31:25.115103-05:
      DOI: 10.1002/cssc.201701450
       
  • Beyond Solar Fuels: Renewable Energy-Driven Chemistry
    • Authors: Paola Lanzafame; Salvatare Abate, Claudio Ampelli, Chiara Genovese, Rosalba Passalacqua, Gabriele Centi, Siglinda Perathoner
      Abstract: The future feasibility of decarbonized industrial chemical production based on the substitution of fossil feedstocks (FFs) with renewable energy (RE) sources is discussed. Indeed, the use of FFs as an energy source has the greatest impact on the greenhouse gas emissions of chemical production. This future scenario is indicated as “solar-driven” or “RE-driven” chemistry. Its possible implementation requires to go beyond the concept of solar fuels, in particular to address two key aspects: i) the use of RE-driven processes for the production of base raw materials, such as olefins, methanol, and ammonia, and ii) the development of novel RE-driven routes that simultaneously realize process and energy intensification, particularly in the direction of a significant reduction of the number of the process steps.I love low-C:Renewable energy (RE)-driven chemistry represents a possible revolution for a low-carbon economy. Its possible implementation requires to go beyond the concept of solar fuels to address two key aspects: the use of RE-driven processes for the production of base raw materials and the development of RE-driven routes that simultaneously realize process and energy intensification.
      PubDate: 2017-11-09T12:30:57.618951-05:
      DOI: 10.1002/cssc.201701507
       
  • Sugar Poly(orthoester) Underwent a Complete Cycle of Depolymerization and
           Repolymerization
    • Authors: Wenjun Du; Lingyao Li, Sampa Maiti, Nicole A Thompson, Lan J Miligan
      Abstract: The capability of a polymer to depolymerize, which regenerates its original monomer for further polymerization, is very attractive in terms of sustainability. Sugar poly(orthoester) was recently synthesized as a novel class of glycopolymer. The high sensitivity of the backbone orthoester linkage towards acidolysis provides a valuable model to study its depolymerization. Herein, we report that the sugar poly(orthoester) can be completely depolymerized at slightly acidic conditions. However, in most cases, the depolymerization gave a stable cyclic product (1,6-anhydro glucopyranose), instead of its original monomer. We discovered that the formation of the cyclic 1,6-anhydro glucopyranose was both kinetically- and thermodynamically-favored. However, this pathway could be shut down by chemically deactivating a key intermediate; shifting the reaction pathway that favors the formation of the original monomer. We further demonstrate that the regenerated monomer can be repolymerized efficiently.
      PubDate: 2017-11-09T08:25:40.396691-05:
      DOI: 10.1002/cssc.201701870
       
  • Isocyanate-free approach to water-borne polyurea dispersions and coatings
    • Authors: Shuang Ma; Ellen van Heeswijk, Bart Noordover, Rafael Sablong, Rolf van Benthem, Cor Koning
      Abstract: In this work, an isocyanate-free approach to produce polyureas from diamines and dicarbamates as monomers is reported. A side reaction limiting molecular weight during the diamine/dicarbamate polymerization, viz. N-alkylation of amine end-groups, is investigated. Mitigation of the N-alkylation, either by enhancing the carbamate aminolysis rate or by substitution of dimethylcarbamates with more sterically hindered diethylcarbamates, affords polyureas with sufficiently high molecular weights to assure satisfactory mechanical properties. Stable polyurea dispersions with polyamines as internal dispersing agents are prepared, and the properties of the corresponding coatings are evaluated.
      PubDate: 2017-11-08T09:56:13.891588-05:
      DOI: 10.1002/cssc.201701930
       
  • Molybdenum-doping augments platinum-copper oxygen reduction
           electrocatalyst
    • Authors: Nicolas Alonso-Vante; Yun Luo, Björn Kirchhoff, Donato Fantauzzi, Laura Calvillo, Luis Alberto Estudillo-Wong, Gaetano Granozzi, Timo Jacob
      Abstract: Improving the efficiency of Pt-based oxygen reduction reaction (ORR) catalysts while also reducing costs remains an important challenge in energy research. To this end, we synthesized highly stable and active carbon-supported Mo-doped PtCu (Mo-PtCu/C) nanoparticles (NPs) from readily available precursors in a facile one-pot reaction. Mo-PtCu/C displays two- to four-fold higher ORR half-cell kinetics than reference PtCu/C and Pt/C materials - a trend which was confirmed in proof-of-concept experiments using a H2/O2 micro-laminar fuel cell. This Mo-induced activity increase mirrors observations for Mo-PtNi/C NPs and possibly suggests an emerging trend. Electrochemical accelerated stability tests revealed that dealloying is greatly reduced in Mo-PtCu/C in contrast to the binaries PtCu/C and PtMo/C. Supporting DFT studies suggest that Mo-PtCu's exceptional stability can be attributed to oxidative resistance of Mo-doped atoms. Furthermore, our calculations revealed that oxygen can induce segregation of Mo to the catalytic surface where it effects beneficial changes to the surface's oxygen adsorption energetics in context of the Sabatier principle.
      PubDate: 2017-11-07T13:20:25.974927-05:
      DOI: 10.1002/cssc.201701822
       
  • WtF-Nano: One-pot dewatering and water-free topochemical modification of
           nanocellulose in ionic liquids or gamma-valerolactone
    • Authors: Tiina Laaksonen; Jussi Kari Juhani Helminen, Laura Lemetti, Jesper Långbacka, Daniel Rico del Cerro, Michael Hummel, Erkko Ilari Filpponen, Antti Rantamäki, Tia Kakko, Marianna Kemell, Susanne Wiedmer, Sami Heikkinen, Ilkka Kilpeläinen, Alistair William Thomas King
      Abstract: It is shown that ionic liquids can be used to dewater birch kraft pulp cellulose nanofibrillar (CNF) suspension and act as a medium for water-free topochemical modification of the nanocellulose. Acetylation, was applied as a model reaction to investigate the degree of modification and scope of effective ionic liquid structures. Little difference in reactivity was observed when water was removed, after introduction of ionic liquid or molecular co-solvent. However, the viscoelastic properties of CNF suspended in two ionic liquids showed that the more basic, but non-dissolving ionic liquid, allows for better solvation of the CNF. Vibrio fischeri bacterials tests showed that all ionic liquids in this study were harmless. Scanning electron microscopy and wide-angle X-ray scattering on regenerated samples show that the acetylated CNF is still in a fibrillar form. 1D and 2D NMR analysis, after direct dissolution in a novel ionic liquid electrolyte solution, identified that both cellulose and residual xylan on the surface of the nanofibrils reacts to give acetate esters
      PubDate: 2017-11-07T08:50:26.592197-05:
      DOI: 10.1002/cssc.201701344
       
  • Electrolyte Engineering towards Efficient Water Splitting at Mild pH
    • Authors: Tatsuya Shinagawa; Marcus Tze-Kiat Ng, Kazuhiro Takanabe
      Abstract: Invited for this month′s cover is the group of Takanabe Kazuhiro at King Abdullah University of Science and Technology (KAUST). The image shows how buffer species plays a crucial role for efficient water electrolysis at near-neutral pH. The Full Paper itself is available at 10.1002/cssc.201701266.“Water splitting is regarded as a core prerequisite to realize sustainable energy technologies…” 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.201701266. View the Front Cover here: 10.1002/cssc.201701993.
      PubDate: 2017-11-06T09:15:36.47062-05:0
      DOI: 10.1002/cssc.201701995
       
  • A New Pentiptycene-Based Dianhydride and Its High-Free-Volume Polymer for
           CO2 Removal
    • Authors: Ahmad Arabi Shamsabadi; Farzad Seidi, Mohammad Nozari, Masoud Soroush
      Abstract: In addition to possessing excellent chemical, mechanical and thermal stability, polyimides and polyetherimides have excellent solubility in many solvents, rendering them suitable for membrane preparation. In this paper, we report the synthesis and characterization of two new monomers [a pentiptycene-based dianhydride (PPDAn) and a pentiptycene imide-containing diamine (PPImDA)], and a pentiptycene-based polyimide [PPImDA-4, 4′-hexafluoroisopropylidene diphthalic anhydride (PPImDA-6FDA)]. The products are characterized using FTIR, 1H NMR, GPC, mass spectroscopy, XPS, TGA, DSC, BET, and XRD. The high molecular-weight PPImDA-6FDA has remarkable thermal stability and excellent solubility in common organic solvents. It also has an extraordinarily high fractional free-volume (0.233) due to the presence of −C(CF3)2− units, the rigid diamine, and the pentiptycene moiety in the polymer structure. It has a high CO2 permeability (812 Barrer) due to its poor chain-packing caused by its rigid groups veiling the influence of the etheric oxygen in its backbone. It has the highest CO2 permeability among all reported pentiptycene-containing polymers (about 6 times higher than the most permeable one) without sacrificing the selectivity. The high free-volume, good microporosity, high solubility in many solvents, and remarkable thermal stability of PPImDA-6FDA point to the great potential of this polymer for CO2 removal.
      PubDate: 2017-11-06T01:15:29.71814-05:0
      DOI: 10.1002/cssc.201701491
       
  • Hierarchical Core-Shell Nickel Cobaltite Chestnut-like Structures as High
           Activity Bi-functional Catalysts for Rechargeable Metal-Air Batteries
    • Authors: Dong Un Lee; Moon Gyu Park, Zachary Paul Cano, Wook Ahn, Zhongwei Chen
      Abstract: Nano-engineered hierarchical core-shell chestnut-like structures have been successfully synthesized as a bi-functionally active electrocatalyst for rechargeable metal-air battery applications. Both the morphology and composition of the catalyst have been optimized by the facile hydrothermal reaction, resulting in the 10-hour treated sample to perform significantly enhanced activity towards facilitating both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Specifically, the catalyst demonstrated -0.28, and 0.60 V vs. SCE at the ORR half-wave potential and the OER current density of 10 mA cm-2, respectively. The resulting ORR/OER potential difference of 0.90 V was the smallest among other catalysts synthesized at 2, 6, and 12 hours. The excellent bi-functional activity of the catalyst is attributed to the nano-scale porous morphology and the spinel nickel cobaltite composition, which improved the active site exposure and transport of reactants and charges during the oxygen reactions.
      PubDate: 2017-11-05T21:55:36.914228-05:
      DOI: 10.1002/cssc.201701832
       
  • Strategies for Efficient Charge Separation and Transfer in Artificial
           Photosynthesis of Solar Fuels
    • Authors: Yuxing Xu; Ailong Li, Tingting Yao, Changtong Ma, Xianwen Zhang, Jafar Hussain Shah, Hongxian Han
      Abstract: Converting sunlight to solar fuels by artificial photosynthesis is aninnovative science and technology for renewableenergy. Light harvesting (LH), photogenerated charge separationand transfer (CST), and catalytic reactions (CR) are the threeprimary steps in the processes of solar energy to chemical energy(SE-CE) conversion. Among them, the CST is the key "energypump and delivery" step in determining the overall solar energyconversion efficiency. Efficient CST is always the priority concernin designing and assembling artificial photosynthesis systems forsolar fuels production. This review not only introduces thefundamental strategies for CST, but also the combinatoryapplication of these strategies in five types of the mostlyinvestigated semiconductor-based artificial photosynthesissystems: particulate, Z-scheme, hybrid, PEC and PV-assistedsystems. It shows that the artificial photosynthesis systems withhigh SE-CE efficiency can be rationally designed and constructedby combinatory application of these strategies, setting apromising blueprint for the future of solar fuels.
      PubDate: 2017-11-04T08:25:24.639687-05:
      DOI: 10.1002/cssc.201701598
       
  • High lithium insertion voltage single-crystal H2Ti12O25 nanorods as high
           capacity and high rate lithium-ion battery anode material
    • Authors: Qiang Guo; Li Chen, Zizhao Shan, Wee Siang Vincent Lee, Wen Xiao, Zhifang Liu, Jingjing Liang, Gaoli Yang, Junmin Xue
      Abstract: H2Ti12O25 holds great promise as high voltage anode material for advanced lithium-ion battery application. In order to enhance its electrochemical performance, controlling crystal orientation and morphology is one of the effective ways to cope the slow Li+ diffusion inside H2Ti12O25 with severe anisotropy. In this report, Na2Ti6O13 nanorods, prepared with Na2CO3 and anatase TiO2 in molten NaCl medium, were used as a precursor in the synthesis of long single-crystal H2Ti12O25 nanorods with reactive facets. As-prepared H2Ti12O25 nanorods with the diameter of 100-200 nm show higher charge (extraction) specific capacity and better rate performance as compared to the previously reported system. The reversible capacity of H2Ti12O25 was 219.8 mAh g-1 at 1C after 100 cycles, 172.1 mAh g-1 at 10 C and 144.4 mAh g-1 at 20 C after 200 cycles, respectively, which were higher than those of H2Ti12O25 prepared by conventional soft-chemical method. Moreover, as-prepared H2Ti12O25 nanorods exhibited superior cycle stability of more than 94% capacity retention with a nearly 100% coulombic efficiency, after 100 cycles at 1C. Based on the above results, long single-crystal H2Ti12O25 nanorods synthesized in molten NaCl with outstanding electrochemical characteristic holds a significant amount of promise for hybrid electric vehicles and energy storage system.
      PubDate: 2017-11-04T07:25:31.62671-05:0
      DOI: 10.1002/cssc.201701479
       
  • H2-assisted CO2 thermochemical reduction on La0.9Ca0.1FeO3-δ
           membranes: a kinetics study
    • Authors: Xiao-Yu Wu; Ahmed F. Ghoniem
      Abstract: Kinetics data for CO2 thermochemical reduction in an isothermal membrane reactor is required to identify the rate-limiting steps. Here, we report a detailed reaction kinetics study on this process supported by an La0.9Ca0.1FeO3-δ (LCF-91) membrane. The dependence of CO2 reduction rate on various operating conditions is examined such as CO2 concentration on the feed side, fuel concentrations on the sweep side and temperatures. CO2 reduction rate is proportional to the oxygen flux across the membrane, and the measured maximum fluxes are 0.191 and 0.164 μmol cm-2 s-1 with 9.5% H2 and 11.6% CO on the sweep side at 990oC, respectively. Fuel is used to maintain the chemical potential gradient across the membrane and CO is used by construction to derive the surface reaction kinetics. This membrane also exhibits stable performances for 106 hours. A resistance-network model is developed to describe the oxygen transport process and the kinetics data are parameterized using the experimental values. The model shows a transition of the rate limiting step between the surface reactions on the feed side and the sweep side depending on the operating conditions.
      PubDate: 2017-11-04T00:30:29.307743-05:
      DOI: 10.1002/cssc.201701372
       
  • Electrochemical Synthesis of Ammonia from Water and Nitrogen: A
           Lithium-Mediated Approach Using Lithium-Ion Conducting Glass Ceramic
    • Authors: Kwiyong Kim; Seung Jong Lee, Dong-Yeon Kim, Chung-Yul Yoo, Jang Wook Choi, Jong-Nam Kim, Youngmin Woo, Hyung Chul Yoon, Jong-In Han
      Abstract: Lithium-mediated reduction of dinitrogen is a promising way to evade electron-stealing hydrogen evolution, a critical challenge which limits faradaic efficiency (FE) and thus hinders the success of traditional protic solvent-based ammonia electro-synthesis. In this study, we propose a viable illustration to realize the lithium-mediated pathway using lithium-ion conducting glass ceramic, which can be divided into three successive steps: (i) lithium deposition, (ii) nitridation, and (iii) ammonia formation. Ammonia was successfully synthesized from molecular nitrogen and water, yielding a maximum FE of 52.3%. With a comparable ammonia synthesis rate to previously reported approaches, the fairly high FE demonstrates the possibility of using this nitrogen fixation strategy as a substitute for the firmly established, yet exceedingly complicated and expensive technology, and in so doing represents a next-generation energy storage system.
      PubDate: 2017-11-03T09:55:28.071443-05:
      DOI: 10.1002/cssc.201701975
       
  • Binder-free hybrid titanium-niobium oxide/carbon nanofiber mats for
           lithium-ion battery electrodes
    • Authors: Aura Tolosa; Simon Fleischmann, Ingrid Grobelsek, Antje Quade, Eunho Lim, Volker Presser
      Abstract: This study introduces the synthesis of free-standing, binder-free, titanium-niobium oxide/carbon hybrid nanofibers for Li-ion battery applications. The one-pot synthesis offers a significant reduction of processing steps and avoids the use of environmentally unfriendly binder materials, making the approach highly sustainable. Tetragonal Nb2O5/C and monoclinic Ti2Nb10O29/C hybrid nanofibers synthesized at 1000 °C presented the highest electrochemical performance, with capacity values of 243 and 267 mAh∙g-1, respectively normalized to the electrode mass. At 5 A∙g-1, the Nb2O5/C and Ti2Nb10O29/C hybrid fibers maintained 78% and 53 % of the initial capacity, respectively. The higher rate performance and stability of tetragonal Nb2O5, compared to monoclinic Ti2Nb10O29, relates to the low energy barriers for Li+ transport in this crystal structure, with no phase transformation. The improved rate performance resulted from the excellent charge propagation in the continuous nanofiber network.
      PubDate: 2017-11-03T03:55:51.587337-05:
      DOI: 10.1002/cssc.201701927
       
  • Hard carbons for sodium ion battery anodes: Synthetic strategies, material
           properties, and storage mechanisms
    • Authors: Malik Wahid; Dhanya Puthusseri, Yogesh Gawli, Neha Sharma, Satishchandra B. Ogale
      Abstract: Na-ion batteries are attracting great interest lately due to their potential as viable future alternatives for Li-ion batteries in view of much higher earth abundance of Na over Li. Although both the battery systems have basically similar chemistries, the key celebrated negative electrode in Li-battery, namely graphite, is unavailable for Na-ion battery due to larger size of Na-ion. This need is satisfied by the so-called "hard carbon" which can internalize the larger Na-ion and has the desirable electrochemical properties. Unlike graphite with its specific layered structure however, hard carbon occurs in diverse microstructural states. In this mini-review we seek to elucidate the connections between precursor choices, synthetic protocols, microstructural states, and performance features of hard carbon forms in the context of Na-ion battery application. Deriving from the pertinent literature employing classical and modern structural characterization techniques, we discuss various issues related to microstructure, morphology, defects, and heteroatom doping. Finally, an outlook is presented suggesting the emergent research directions.
      PubDate: 2017-11-03T02:55:28.055838-05:
      DOI: 10.1002/cssc.201701664
       
  • Production of Low-Freezing-Point Highly Branched Alkanes via Michael
           Addition
    • Authors: Yanqin Wang; Yaxuan Jing, Qineng Xia, Xiaohui Liu
      Abstract: A new approach for the production of low freezing point, high-quality fuels from lignocellulose derived molecules was developed with Michael addition as the key step. Among the investigated catalysts, CoCl2*6H2O was found to be the most active for Michael addition of 2,4-pentanedione with FA (single aldol adduct of furfural and acetone, 4-(2-furanyl)-3-butene-2-one). Over CoCl2*6H2O, a high carbon yield of C13 oxygenates (about 75%) can be achieved under mild conditions (353 K, 20 h). After hydrodeoxygenation, low freezing point (< 223 K) branched alkanes with 13 carbons within jet fuel ranges were obtained over Pd/NbOPO4 catalyst. Furthermore, C18,23 fuel precursors could be easily synthesized through Michael addition of 2,4-pentanedione with DFA (double-condensation product of furfural and acetone) under mild conditions and the molar ratio of C18/C23 is dependent on the reaction conditions of Michael addition. After hydrodeoxygenation, high density (0.8415 g/ml) and low freezing point (< 223 K) branched alkanes with 18, 23 carbons with lubricant range were also obtained over Pd/NbOPO4 catalyst. These highly branched alkanes can be directly used as transportation fuels or additives. This work opens a novel strategy for the synthesis of highly branched alkanes with low-freezing-point from renewable biomass.
      PubDate: 2017-11-02T22:01:36.231912-05:
      DOI: 10.1002/cssc.201701789
       
  • Hydrogen Evolution by Fe(III) molecular electrocatalysts interconverting
           between mono and di-nuclear structures in aqueous phase
    • Authors: Marcella Bonchio; Mirko Tagliapietra, Andrea Squarcina, Neal Kickey, Rita De Zorzi, Silvano Geremia, Andrea Sartorel
      Abstract: A novel FeL/Fe₂L₂ manifold, with HL= 2-{[[di(2-pyridyl)methyl] (methyl)amino]methyl}phenol, has been prepared in gram scale (>50% yield) and characterized in solution and solid state. The monomer/dimer interconversion is controlled in aqueous phase, upon varying the pH conditions. The electrocatalytic hydrogen evolving reaction (HER) occurs through the FeL monomer with added acid (TFA) and through the Fe₂L₂ µ-hydroxo dimer in acetate buffer (pH = 4.9), with overpotential of ca 1 V and faradaic yield up to 75%. The resulting iCAT/iP values in the range 15-28 are among the highest reported for iron-based electrocatalysts.
      PubDate: 2017-11-02T12:55:25.509889-05:
      DOI: 10.1002/cssc.201701612
       
  • Multiple trapping model for the charge recombination dynamics in
           mesoporous-structured perovskite solar cells
    • Authors: Hao-Yi Wang; Yi Wang, Ming-Yang Hao, Yujun Qin, Li-Min Fu, Zhi-Xin Guo, Xi-Cheng Ai, Jian-Ping Zhang
      Abstract: The photovoltaic performance of organic-inorganic hybrid perovskite solar cells has reached a bottleneck after the rapid development in last few years, and further breakthrough requires a deeper understanding about the underlying mechanism of the photoelectric conversion process in the device, especially the dynamics of charge carrier recombination. Originated from dye-sensitized solar cells (DSSCs), mesoporous-structured perovskite solar cells (MPSCs) have shown obvious similarity in the photoelectric dynamics with DSSCs in many aspects. Herein, by incorporating the classic multiple trapping model of the charge recombination dynamic process for DSSCs into MPSCs with rational modification, a novel physical model is proposed to describe the dynamics of charge recombination in MPSCs, which exhibits good agreement with the experimental data. Accordingly, the perovskite-dominating and the TiO₂-dominating charge recombination processes are assigned, respectively, and their relationships with the trap-state distribution are also discussed. An optimal balance between these two dynamic processes is required for the performance improvement of the mesoporous-structured perovskite device.
      PubDate: 2017-11-02T03:26:00.096328-05:
      DOI: 10.1002/cssc.201701780
       
  • Highly Efficient and Robust Enantioselective Liquid-Liquid Extraction of
           1,2-Amino Alcohols Utilising VAPOL- and VANOL-based Phosphoric Acid Hosts.
           
    • Authors: Johannes Gerardus de Vries; Erik B. Pinxterhuis, Jean-Baptiste Gualtierotti, Sander J. Wezenberg, Ben L. Feringa
      Abstract: The large-scale production of enantiopure compounds in a cost-effective and environmentally friendly manner remains one of the major challenges of modern day chemistry. The resolution of racemates via enantioselective liquid-liquid extraction was developed as a suitable solution but has remained largely underused due to a lack of highly efficient and robust chiral hosts to mediate the process. This paucity of hosts can in part be attributed to a feeble understanding of the underlying principles behind these processes hindering the design of more efficient selectors. Herein, we present an in depths study of a previously untested class of hosts, VAPOL and VANOL derived phosphoric acids, for the efficient enantioselective liquid-liquid extraction of 1,2-amino alcohols. A systematic investigation of extraction parameters was conducted revealing many key interactions, while DFT calculations illustrate the binding modes for the 1:1 complexes that are involved in chiral recognition. The resulting, now optimised, procedures, are highly robust and easy to implement. They are also easily scalable as was demonstrated by U-tube experiments.
      PubDate: 2017-11-01T12:20:33.787357-05:
      DOI: 10.1002/cssc.201701896
       
  • Selective Liaison With Liquids for Environment-Friendly and Comprehensive
           Oil/Water Separation
    • Authors: Dibyangana Parbat; Uttam Manna
      Abstract: A hydrophobic three dimensional material—having smart affair with oil phase, is developed using a scalable and facile Micheal addition reaction at ambient condition, without using any catalyst. The synthesized material is capable of absorbing both heavy/light oils with efficiency above 1000 weight %. This super-oil-absorbance property remained intact in diverse scenarios, including extremes of temperature (100°C and 10°C), pressure (184.7mbar), and prolonged (7 days) exposures to extremes of pH (1/12), surfactants (DTAB/SDS, 1mM)-contaminated water, artificial sea water etc. This super-oil-absorbent with impeccable durability was exploited further in demonstrations of comprehensive and facile clean-up from various forms of oil/water mixtures (i.e., floating oil, sediment oil, emulsions etc.) in extremes and complex settings that are relevant to practical scenarios including marine-oil-spills, following eco-friendly and energy-efficient selective-absorption/active-filtration principles.
      PubDate: 2017-10-30T06:08:32.056761-05:
      DOI: 10.1002/cssc.201701791
       
  • A functional hydrogenase mimic chemisorbed onto FTO electrodes; a strategy
           towards water splitting devices
    • Authors: riccardo Zaffaroni; Remko Detz, Jarl Ivar van der Vlugt, Joost Reek
      Abstract: In this contribution, we describe the preparation, characterization and immobilization studies of a benzene dithiolale di-iron hydrogen evolving catalyst, first step towards the development of water splitting devices based on molecular components. FTO (fluorine doped tin oxide), was chosen as the preferred electrode material due to its conductive properties and electrochemical stability. We also report, the use of FTO nano-crystals to greatly improve the surface area of commercially available FTO whilst preserving the properties of the material. Catalyst modified electrodes are shown to be competent for electrocatalytic hydrogen evolution from acidic aqueous media at relatively low overpotential (500 mV) with a Faradaic efficiency close to unity, representing the first hydrogen evolving electrodes based on di-iron hydrogenase synthetic models. We show that the catalyst operates at roughly 160 mV lower overpotentials, yet with similar rates, when immobilized onto the electrode surface.
      PubDate: 2017-10-27T10:35:40.077056-05:
      DOI: 10.1002/cssc.201701757
       
  • Electrolyte Engineering towards Efficient Water Splitting at Mild pH
    • Authors: Tatsuya Shinagawa; Marcus Tze-Kiat Ng, Kazuhiro Takanabe
      Abstract: The Front Cover shows buffer ions participating as “catalysts” in the water splitting process. On the anode (left), oxygen evolves through the oxidation of water molecules to generate protons, which are captured and transported by the buffer species. These buffer species then carry the protons to the cathodic catalytic sites (right), where hydrogen is generated. The overall performance is significantly influenced by the mass transport of the buffer species and the kinetics of the electrocatalysts. Maximizing the flux of the buffer species can be systematically achieved by electrolyte engineering at near-neutral pH. More information can be found in the Full Paper by Shinagawa et al.
      PubDate: 2017-10-27T05:01:37.587374-05:
      DOI: 10.1002/cssc.201701993
       
  • Ring-Opening Polymerization of l-Lactide to Cyclic Poly(Lactide) by
           Zeolitic Imidazole Framework ZIF-8 Catalyst
    • Authors: Zhixiong Luo; Somboon Chaemchuen, Kui Zhou, Francis Verpoort
      Abstract: The Cover Feature shows a new approach to cyclic polylactide in the bulk ring-opening polymerization (ROP) of l-lactide by using ZIF-8 as a heterogeneous catalyst. The ZIF-8 catalyst assembled by spray-drying technique displays high efficiency and good recyclability for this ROP reaction. The active acid and basic sites in ZIF-8 are supposed to cooperatively catalyze the ROP reaction, particularly forming cyclic polylactide with high molecular weight. More information can be found in the Communication by Luo et al.
      PubDate: 2017-10-27T05:01:33.479658-05:
      DOI: 10.1002/cssc.201701996
       
  • 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: The Cover Feature demonstrates the importance of differentiation between several degradation phenomena that appear in lab-scale accelerated stress tests for oxygen evolution reaction (OER) materials. The provided insights are essential for interpretation of electrochemical degradation results and eventually for identifying best catalysts. More information can be found in the Communication by Geiger et al.
      PubDate: 2017-10-27T05:01:30.611342-05:
      DOI: 10.1002/cssc.201701997
       
  • Promoting photocatalytic overall water splitting by controlled
           Mg-incorporation in SrTiO3 photocatalysts
    • Authors: Kai Han; Yen-Chun Lin, Chia-Min Yang, Ronald Jong, Guido Mul, Bastian Mei
      Abstract: SrTiO3 is a well-known photocatalyst inducing overall water splitting when exposed to UV irradiation of wavelengths < 370 nm. However, the apparent quantum efficiency of SrTiO3 is typically low, even when functionalized with nanoparticles of Pt or Ni@NiO. Here, we introduce a simple solid state preparation method to control the incorporation of magnesium into the perovskite structure of SrTiO3. After deposition of Pt or Ni@NiO, the photocatalytic water splitting efficiency of the Mg:SrTiOx composites is up to 20 times higher as compared to SrTiO3 containing similar catalytic nanoparticles, and an apparent quantum yield (AQY) of 10 % can be obtained in the wavelength range of 300 - 400 nm. Detailed characterization of the Mg:SrTiOx composites revealed that Mg is likely substituting the tetravalent Ti-ion, leading to a favorable surface-space-charge layer. This originates from tuning of the donor density in the cubic SrTiO3 structure by Mg-incorporation, and enables high oxygen evolution rates. Nevertheless, interfacing with an appropriate hydrogen evolution catalyst is mandatory and non-trivial, to obtain high performance in water splitting.
      PubDate: 2017-10-26T07:05:23.004511-05:
      DOI: 10.1002/cssc.201701794
       
  • Review of natural product-derived carbon dots: from natural products to
           functional materials
    • Authors: Xinyue Zhang; Mingyue Jiang, Na Niu, Zhijun Chen, Shujun Li, Shouxin Liu, Jian Li
      Abstract: Nature provides an almost limitless supply of natural sources, which inspires scientists to develop new materials with novel applications and less environmental impact. Recently, much attention has focused on preparing natural product-derived carbon dots (NCDs) because of several advantages of natural products. First of all, natural products are renewable and have good biocompatibility. Secondly, Natural products contain heteroatoms, which facilitates the fabrication of heteroatom-doped NCDs without addition of external heteroatom sources. Finally, some natural products can be used to prepare NCDs in very green and simple way, compared to traditional methods for carbon dots from man-made carbon sources. NCDs have shown tremendous potential in many fields, including biosensing, bioimaging, optoelectronics and photocatalysis. However, there have been no reviews that specifically cover NCDs. To address this deficiency, we now provide a review of recent progress in the synthesis, properties and applications of NCDs. The challenges and future direction of NCD-based materials research in this booming field will also be discussed.
      PubDate: 2017-10-26T04:30:26.139026-05:
      DOI: 10.1002/cssc.201701847
       
  • Sodium-Containing Spinel Zinc Ferrite as a Catalyst Precursor for the
           Selective Synthesis of Liquid Hydrocarbon Fuels
    • Authors: Yo Han Choi; Eun Cheol Ra, Eun Hyup Kim, Kwang Young Kim, Youn Jeong Jang, Kyeong-Nam Kang, Sun Hee Choi, Ji-Hyun Jang, Jae Sung Lee
      Abstract: A microwave-assisted hydrothermal synthesis produces ZnFe2O4 containing Na residue as a precursor to a CO2 hydrogenation catalyst that displays high CO2 conversion and high selectivity to liquid hydrocarbon products in the gasoline and diesel range with high olefin-to-paraffin ratios. Compared to reference catalysts derived from Fe2O3 and a ZnO–Fe2O3 physical mixture, the ZnFe2O4-derived catalyst contains well-dispersed iron particles with Zn serving as a structural promoter. A profound effect of the residual Na as an electronic promoter is also observed, which improves the selectivity for C5+ hydrocarbons and olefins. The ZnFe2O4-derived catalyst exhibits excellent performance in the CO2 Fischer–Tropsch reaction as it forms the active Hägg iron carbide (χ-Fe5C2) phase readily through the in situ carburization of iron.It's a gas: A catalyst derived from spinel ZnFe2O4 containing Na residue displays high CO2 hydrogenation activity and liquid-fuel selectivity in the gasoline and diesel range with high olefin-to-paraffin ratios.
      PubDate: 2017-10-25T10:08:16.371312-05:
      DOI: 10.1002/cssc.201701437
       
  • Liquid Hydrocarbon Production from CO2: Recent Development in
           Electrocatalysts
    • Authors: Rahman Daiyan; Xunyu Lu, Yun Hau Ng, Rose Amal
      Abstract: Rising levels of CO2 accumulation in the atmosphere has attracted considerable interest in technologies capable of CO2 capture, storage and conversion. The electrochemical reduction of CO2 into high value liquid organic products could be of vital importance to mitigate this issue. The conversion of CO2 to liquid fuels using photovoltaic cells, which can readily be integrated in the current infrastructure, will help realize the creation of a sustainable cycle of carbon based fuel that will promote zero net CO2 emissions. Despite the promising findings, significant challenges still persist that must be circumvented to make the technology profitable for large scale utilization. With such possibilities, this review presents the current high performing catalysts for the electrochemical reduction of CO2 to liquid hydrocarbons, address the limitations and unify the current understanding of the different reaction mechanisms. The review also explores current research directions to improve process efficiencies and production rate and discusses the scope of using photo-assisted electrochemical reduction systems to find stable, highly efficient catalysts that can harvest solar energy directly to convert CO2 into liquid hydrocarbons.
      PubDate: 2017-10-25T06:37:41.288941-05:
      DOI: 10.1002/cssc.201701631
       
  • Ru water oxidation catalysts based on py5 ligands
    • Authors: Marcos Gil-Sepulcre; Mauro Schilling, Michael Boehler, Fernando Bozoglian, Cyril Bachmann, Dominik Scherrer, Thomas Fox, Bernhard Spinlger, Carolina Gimbert-Suriñach, Roger Alberto, Roger Bofill, Xavier Sala, Sandra Luber, Craig Richmond, Antoni Llobet
      Abstract: Ru complexes containing the pentapyridyl ligand 6,6''-(methoxy(pyridin-2-yl)methylene)di-2,2'-bipyridine (L-OMe) of general formula trans-[RuII(X)(L-OMe--N5)]n+ (X = Cl, n = 1, trans-1+; X = H2O, n = 2, trans-22+) have been isolated and characterized in solution (NMR, UV-Vis) and in the solid state by XRD. Both complexes suffer a series of substitution reactions at oxidation state II and III, when dissolved in aqueous triflic acid-trifluroethanol solutions that have been monitored by UV-vis spectroscopy and their corresponding rate constants reported. In particular, aqueous solutions of the RuIII-Cl complex trans-[RuIII(Cl)(L-OMe--N5)]2+ (trans-12+) generates a family of Ru-aqua complexes namely trans-[RuIII(H2O)(L-OMe--N5)]3+ (trans-23+), [RuIII(H2O)2(L-OMe--N4)]3+ (trans-33+) and [RuIII(Cl)(H2O)(L-OMe--N4)]3+ (trans-42+). While complex trans-42+ is a powerful water oxidation catalyst, complex trans-23+ has only a moderate activity and trans-33+ is not a catalyst. Further, a parallel work has been carried out with related complexes but containing the methyl substituted ligand 6,6''-(1-pyridin-2-yl)ethane-1,1-diyl)di-2,2'-bipyridine (L-Me). The behavior of all these catalysts has been rationalized based on substitution kinetics, oxygen evolution kinetics, electrochemical properties and DFT calculations. The best catalysts, trans-42+, reach turnover frequencies of 0.71 s-1 using Ce(IV) as a sacrificial chemical oxidant with oxidative efficiencies above 95%
      PubDate: 2017-10-25T06:37:14.863758-05:
      DOI: 10.1002/cssc.201701747
       
  • Adsorption and selective recovery of citric acid with
           poly(4-vinylpyridine)
    • Authors: Matthias Van den Bergh; Ben Van de Voorde, Dirk De Vos
      Abstract: Citric acid (CA) is an important organic acid that is produced on a large scale by fermentation. Current methods to recover CA from the fermentation broth require large amounts of chemicals and produce considerable amounts of waste, while not all CA can be recovered. The use of adsorbents can increase the degree of product recovery and reduce chemical consumption and waste generation. In this work poly(4-vinylpyridine) (PVP) is evaluated as adsorbent for CA recovery. It has a high adsorption capacity (>30 wt%) at low pH and a high selectivity for CA at moderate pH in the presence of sulphate anions, two conditions that are frequently encountered during CA recovery. PVP could be efficiently regenerated after adsorption using simple alcohols like methanol and ethanol. Considering selectivity and regeneration, PVP distinctly outperforms more common adsorbents for organic acids, like commercial strongly and weakly basic anion exchangers. The desirable adsorptive features of PVP for CA can be attributed to the low basicity of the pyridine group.
      PubDate: 2017-10-24T10:50:29.263861-05:
      DOI: 10.1002/cssc.201701672
       
  • Reconsidering water electrolysis: producing H2 at cathodes together with
           valuable chemicals at anodes. Selective anodic oxidation of n-butylamine
           to n-butyronitrile as an example
    • Authors: Song Xue; Sebastian Watzele, Victor Čolić, Kurt Brandl, Batyr Garlyyev, Aliaksandr Bandarenka
      Abstract: Electrocatalysis of the oxygen evolution reaction is of great interest for improving the effectiveness of water splitting devices. Decreasing the anodic overpotential and simultaneously changing anode reaction selectively, producing valuable chemicals instead of O2, would be a major improvement of the overall cost efficiency. Recently it was shown that some amines, when present in aqueous electrolytes, change the selectivity of the anodic process generating H2O2 rather than O2 on MnOx at pH=10. This results in unusually high apparent "anodic activities". In this work, we show industrially relevant OER catalysts: oxy-hydroxides of cobalt (CoOx), nickel/iron (NiFeOx) and nickel (NiOx) all show more pronounced effects; also by using these catalysts we selectively produce n-butyronitrile from n-butylamine at higher pHs as an easily retrievable valuable product. The pH-dependence of the activity was investigated at pH values, closer to ones at which alkaline electrolyzers operate. The highest activities were observed for NiOx thin film electrodes at pH=12 in presence of 0.4M n-butylamonium sulfate, without poisoning the active sites of Pt electrocatalysts from the hydrogen evolution electrode side. 1H-NMR showed that n-butylamine is selectively oxidized to n-butyronitrile, an organic chemical with numerous applications. However, the measurements using rotating ring-disk electrodes also provide a proof that some H2O2 is also generated at the surface of the oxide anodes.
      PubDate: 2017-10-24T04:00:56.266506-05:
      DOI: 10.1002/cssc.201701802
       
  • Ligand Controlled Electrodeposition of Highly Intrinsic Active and
           Optically Transparent NiFeOxHy Film as Electrocatalytic Water Oxidation
           Catalyst
    • Authors: Husileng Lee; Xiujuan Wu, Xiaonan Yang, Licheng Sun
      Abstract: A highly intrinsic active and optically transparent NiFeOxHy water oxidation catalyst was prepared by electrodeposition of [Ni(C12-tpen)](ClO4)2 complex (Ni-C12). This NiFeOxHy film exhibits a current density of 10 mA cm-2 with an overpotential (η) of only 298 mV at nanomolar concentration and the current density of 10 mA cm-2 remains constant over 20 h in 1 M KOH. The extremely high TOFs of 0.51 s-1 was obtained with η of 300 mV. More importantly, such outstanding activity and transparency (optical loss < 0.5%) of NiFeOxHy film are attributed to ligand effect of dodecyl substituent in Ni-C12 complex which enable its future application in solar water splitting.
      PubDate: 2017-10-22T20:55:35.872841-05:
      DOI: 10.1002/cssc.201701869
       
  • 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
       
  • 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
       
  • 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: : 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
 
 
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