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  Subjects -> CHEMISTRY (Total: 860 journals)
    - ANALYTICAL CHEMISTRY (53 journals)
    - CHEMISTRY (603 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (42 journals)
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CHEMISTRY (603 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 12)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26)
ACS Catalysis     Full-text available via subscription   (Followers: 40)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 20)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 25)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 41)
ACS Nano     Full-text available via subscription   (Followers: 259)
ACS Photonics     Full-text available via subscription   (Followers: 12)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 23)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription   (Followers: 1)
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chimica Slovenica     Open Access  
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 8)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 51)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 59)
Advances in Chemical Science     Open Access   (Followers: 14)
Advances in Chemistry     Open Access   (Followers: 16)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18)
Advances in Drug Research     Full-text available via subscription   (Followers: 23)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 24)
Advances in Nanoparticles     Open Access   (Followers: 14)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 16)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 12)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 2)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 67)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 15)
American Journal of Chemistry     Open Access   (Followers: 28)
American Journal of Plant Physiology     Open Access   (Followers: 14)
American Mineralogist     Hybrid Journal   (Followers: 15)
Analyst     Full-text available via subscription   (Followers: 40)
Angewandte Chemie     Hybrid Journal   (Followers: 168)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 238)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 4)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 16)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 22)
Applied Surface Science     Hybrid Journal   (Followers: 28)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Full-text available via subscription   (Followers: 338)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 1)
Biomacromolecules     Full-text available via subscription   (Followers: 19)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 121)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 85)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 69)
Catalysis for Sustainable Energy     Open Access   (Followers: 7)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 9)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 16)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 71)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 25)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 22)
Chemical Reviews     Full-text available via subscription   (Followers: 189)
Chemical Science     Open Access   (Followers: 23)
Chemical Technology     Open Access   (Followers: 16)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemical Week     Full-text available via subscription   (Followers: 8)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 24)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 31)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry - A European Journal     Hybrid Journal   (Followers: 155)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 43)
Chemistry of Materials     Full-text available via subscription   (Followers: 246)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 22)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 4)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 11)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography     Open Access   (Followers: 2)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 10)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 22)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 3)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 6)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal  
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 18)
Current Research in Chemistry     Open Access   (Followers: 9)
Current Science     Open Access   (Followers: 64)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 4)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 3)

        1 2 3 4 | Last

Journal Cover Advanced Functional Materials
  [SJR: 5.21]   [H-I: 203]   [51 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1616-301X - ISSN (Online) 1616-3028
   Published by John Wiley and Sons Homepage  [1592 journals]
  • Elemental Ferroelectricity and Antiferroelectricity in Group-V Monolayer
    • Authors: Chengcheng Xiao; Fang Wang, Shengyuan A. Yang, Yunhao Lu, Yuanping Feng, Shengbai Zhang
      Abstract: Ferroelectricity is usually found in compound materials composed by different elements. Here, based on first-principles calculations, spontaneous electric polarization and ferroelectricity in 2D elemental group-V (As, Sb, and Bi) monolayer with the puckered lattice structure similar to phosphorene is revealed. These are the first example of elemental ferroelectric materials. The polarization is due to the spontaneous lattice distortion with atomic layer buckling and has quite sizable values, comparable or even larger than that recently found in 2D monolayer compound SnTe. Interestingly, for Bi monolayer, apart from the ferroelectric phase, it is found that it can also host an antiferroelectric phase. The Curie temperatures of these elemental materials can be higher than room temperature, making them promising for realizing ultrathin ferroelectric devices of broad interest. A general model is constructed to understand and search for 2D ferroelectric and antiferroelectric materials in future studies.Robust ferroelectricity is predicted in 2D elemental group-V (As, Sb, and Bi) monolayers with the puckered lattice structure similar to phosphorene. Interestingly, for Bi monolayer, a metastable antiferroelectric phase is also found. The revealed phase-change mechanism for such elemental monolayer takes to deeply understand the effect of s-p hybridization on stability and distortion of 2D system.
      PubDate: 2018-02-23T03:11:44.870176-05:
      DOI: 10.1002/adfm.201707383
       
  • Transparent, Anisotropic Biofilm with Aligned Bacterial Cellulose
           Nanofibers
    • Authors: Sha Wang; Tian Li, Chaoji Chen, Weiqing Kong, Shuze Zhu, Jiaqi Dai, Alfredo J. Diaz, Emily Hitz, Santiago D. Solares, Teng Li, Liangbing Hu
      Abstract: Cellulose nanofibrils are attractive as building blocks for advanced photonic, optoelectronic, microfluidic, and bio-based devices ranging from transistors and solar cells to fluidic and biocompatible injectable devices. For the first time, an ultrastrong and ultratough cellulose film, which is composed of densely packed bacterial cellulose (BC) nanofibrils with hierarchical fibril alignments, is successfully demonstrated. The molecular level alignment stems from the intrinsic parallel orientation of crystalline cellulose molecules produced by Acetobacter xylinum. These aligned long-chain cellulose molecules form subfibrils with a diameter of 2–4 nm, which are further aligned to form nanofibril bundles. The BC film yields a record-high tensile strength (≈1.0 GPa) and toughness (≈25 MJ m−3). Being ultrastrong and ultratough, yet the BC film is also highly flexible and can be folded into desirable shapes. The BC film exhibits a controllable manner of alignment and is highly transparent with modulated optical properties, paving the way to enabling new functionalities in mechanical, electrical, fluidic, photonics, and biocompatible applications.A transparent and anisotropic cellulose biofilm from bacteria cellulose (BC) is constructed via a well-developed stretching process. The hierarchical alignment of high quality cellulose fibrils renders the biofilm ultrastrong and ultratough. With tailored nanoscale and microscale morphology of stretched BC paper, the optical properties can be dramatically modulated with well-controlled anisotropic transmission patterns, enabling new photonic applications.
      PubDate: 2018-02-23T03:06:43.33473-05:0
      DOI: 10.1002/adfm.201707491
       
  • Direct Growth of Edge-Rich Graphene with Tunable Dielectric Properties in
           Porous Si3N4 Ceramic for Broadband High-Performance Microwave Absorption
    • Authors: Fang Ye; Qiang Song, Zhenchuang Zhang, Wei Li, Shouyang Zhang, Xiaowei Yin, Yuzhao Zhou, Huiwen Tao, Yongsheng Liu, Laifei Cheng, Litong Zhang, Hejun Li
      Abstract: High-performance graphene microwave absorption materials are highly desirable in daily life and some extreme situations. A simple technique for the direct growth of graphene as absorption fillers in wave-transmitting matrices is of paramount importance to bring it to real-world application. Herein, a simple chemical vapor deposition (CVD) route for the direct growth of edge-rich graphene (ERG) with tailored structures and tunable dielectric properties in porous Si3N4 ceramics using only methyl alcohol (CH3OH) as precursor is reported. The large O/C atomic ratio of CH3OH helps to build a mild oxidizing atmosphere and leads to a unique structure featuring open graphite nanosteps and freestanding nanoplanes, endowing the ERG/Si3N4 hybrid with an appropriate balance between good impedance matching and strong loss capacity. Accordingly, the prepared materials exhibit superior electromagnetic wave absorption, far surpassing that of traditional CVD graphene and reduced graphene oxide-based materials, achieving an effective absorption bandwidth of 4.2 GHz covering the entire X band, with a thickness of 3.75 mm and a negligibly low loading content of absorbents. The results provide new insights for developing novel microwave absorption materials with strong reflection loss and wide absorption frequency range.Edge-rich graphene (ERG) with tunable dielectric properties has been grown in porous Si3N4 ceramic by a simple chemical vapor deposition method using methyl alcohol as precursor. ERG/Si3N4 hybrids exhibit superior electromagnetic wave absorption, due to the unique structure of ERG and the resulted good impedance matching.
      PubDate: 2018-02-23T02:30:41.362651-05:
      DOI: 10.1002/adfm.201707205
       
  • Fabrication of Nickel–Cobalt Bimetal Phosphide Nanocages for Enhanced
           Oxygen Evolution Catalysis
    • Authors: Bocheng Qiu; Lejuan Cai, Yang Wang, Ziyuan Lin, Yunpeng Zuo, Mengye Wang, Yang Chai
      Abstract: Replacement of precious metals with earth-abundant electrocatalysts for oxygen evolution reaction (OER) holds great promise for realizing practically viable water-splitting systems. It still remains a great challenge to develop low-cost, highly efficient, and durable OER catalysts. Here, the composition and morphology of Ni–Co bimetal phosphide nanocages are engineered for a highly efficient and durable OER electrocatalyst. The nanocage structure enlarges the effective specific area and facilitates the contact between catalyst and electrolyte. The as-prepared Ni–Co bimetal phosphide nanocages show superior OER performance compared with Ni2P and CoP nanocages. By controlling the molar ratio of Ni/Co atoms in Ni–Co bimetal hydroxides, the Ni0.6Co1.4P nanocages derived from Ni0.6Co1.4(OH)2 nanocages exhibit remarkable OER catalytic activity (η = 300 mV at 10 mA cm−2) and long-term stability (10 h for continuous test). The density-functional-theory calculations suggest that the appropriate Co doping concentration increases density of states at the Fermi level and makes the d-states more close to Fermi level, giving rise to high charge carrier density and low intermedia adsorption energy than those of Ni2P and CoP. This work also provides a general approach to optimize the catalysis performance of bimetal compounds.Ni–Co bimetal phosphide nanocages as highly efficient and robust electrocatalysts are synthesized by using Cu2O nanocubes templates. Through accurate regulation of Co doping concentration, the optimum oxygen evolution reaction performance can be achieved. Theoretical analysis suggests that the Co incorporation into Ni2P effectively optimizes the electronic structures of bimetal phosphide catalysts and enhances their interaction with reactants.
      PubDate: 2018-02-23T02:26:50.214001-05:
      DOI: 10.1002/adfm.201706008
       
  • Addressing Passivation in Lithium–Sulfur Battery Under Lean
           Electrolyte Condition
    • Authors: Huilin Pan; Kee Sung Han, Mark H. Engelhard, Ruiguo Cao, Junzheng Chen, Ji-Guang Zhang, Karl T. Mueller, Yuyan Shao, Jun Liu
      Abstract: Reducing the electrolyte amount is critical for the high specific energy of lithium–sulfur (Li–S) batteries in practice. The reduced electrolyte condition (a so-called “lean electrolyte”) raises a complex situation for sulfur redox reactions since the reactions rely on the electrolyte mediation. The insulating nature of discharge product Li2S and its uncontrollable accumulation (passivation) at the cathode interface is one of the major challenges for stable cycling of a Li–S battery under lean electrolyte condition. In this study, it is presented that the NH4TFSI additive in electrolyte solution greatly alleviates the passivation issue in Li–S batteries under lean electrolyte conditions. The ammonium additive enhances the dissociation of Li2S and largely reduces the insoluble and large Li2S particles in the sulfur cathodes, which facilitate the reversible and sustainable redox reactions of sulfur. Therefore, the cycle life of Li–S batteries under lean electrolyte conditions is significantly improved. In addition, it is found that the morphology of Li anodes is dependent on the cathode structures. An ammonium additive enables homogeneous surface of cathode and Li anode and extended cycle life.Addressing the passivation issue of insulating Li2S is extremely critical to extend the cycle life of lithium–sulfur batteries, especially under the lean electrolyte condition. An electrolyte additive promoting the dissociation of Li2S is an effective solution to prevent the uncontrollable accumulation of Li2S, leading to an active S cathode interface and homogeneous Li metal deposition morphology.
      PubDate: 2018-02-23T02:26:21.644432-05:
      DOI: 10.1002/adfm.201707234
       
  • Catalyst-Free, Fast, and Tunable Synthesis for Robust Covalent Polymer
           Network Semiconducting Thin Films
    • Authors: Liang Yao; Aiman Rahmanudin, Xavier A. Jeanbourquin, Xiaoyun Yu, Melissa Johnson, Néstor Guijarro, Arvindh Sekar, Kevin Sivula
      Abstract: Covalent polymer networks (CPNs) are of great technological interest due to their robustness and tunability; however, they are rarely applied as semiconductors in optoelectronic devices due to poor material processability. Herein, a simple, rapid, and powerful approach is reported to prepare CPN thin films based on an in situ thermal azide–alkyne cycloaddition (TAAC) in the absence of catalyst or solvent. The method is demonstrated with perylenediimide and triazine-based monomers, and affords smooth and homogenous CPN films through solution processing and heat treatment (10 min). Moreover, the site-specific TAAC realizes semiconducting CPNs without undesired impurities or byproducts, and tunable optoelectronic properties are achieved by varying the reaction temperature, which affects the intermolecular self-assembly. The obtained CPN films exhibit exceptional solvent resistance and good n-type semiconducting behavior, which together afford application in a series of multilayer solution-processed organic photovoltaics, where the presence of CPN films significantly improves the solar energy conversion efficiency to over 8% (7% in control devices) when the CPN is used in a planar-mixed heterojunction device architecture.A simple, rapid, and powerful approach to fabricate covalent polymer network (CPN) films is demonstrated. Through a simple in situ heating process, CPN films with high quality are obtained. The resulting CPN films with n-type semiconductor properties exhibit a thermally stable morphology, excellent solvent resistance, and application in organic photovoltaics.
      PubDate: 2018-02-22T04:06:00.273104-05:
      DOI: 10.1002/adfm.201706303
       
  • Versatile Surface Functionalization of Metal–Organic Frameworks through
           Direct Metal Coordination with a Phenolic Lipid Enables Diverse
           Applications
    • Authors: Wei Zhu; Guolei Xiang, Jin Shang, Jimin Guo, Benyamin Motevalli, Paul Durfee, Jacob Ongudi Agola, Eric N. Coker, C. Jeffrey Brinker
      Abstract: A novel strategy for the versatile functionalization of the external surface of metal-organic frameworks (MOFs) has been developed based on the direct coordination of a phenolic-inspired lipid molecule DPGG (1,2-dipalmitoyl-sn-glycero-3-galloyl) with metal nodes/sites surrounding MOF surface. X-ray diffraction and Argon sorption analysis prove that the modified MOF particles retain their structural integrity and porosity after surface modification. Density functional theory calculations reveal that strong chelation strength between the metal sites and the galloyl head group of DPGG is the basic prerequisite for successful coating. Due to the pH-responsive nature of metal-phenol complexation, the modification process is reversible by simple washing in weak acidic water, showing an excellent regeneration ability for water-stable MOFs. Moreover, the colloidal stability of the modified MOFs in the nonpolar solvent allows them to be further organized into 2 dimensional MOF or MOF/polymer monolayers by evaporation-induced interfacial assembly conducted on an air/water interface. Finally, the easy fusion of a second functional layer onto DPGG-modified MOF cores, enabled a series of MOF-based functional nanoarchitectures, such as MOFs encapsulated within hybrid supported lipid bilayers (so-called protocells), polyhedral core-shell structures, hybrid lipid-modified-plasmonic vesicles and multicomponent supraparticles with target functionalities, to be generated. for a wide range of applications.A novel strategy for versatile functionalization of metal–organic frameworks (MOFs) surface has been developed based on the coordination of lipid molecule 1,2-dipalmitoyl-sn-glycero-3-galloyl with metal nodes. Several functions including the reversible surface modification, the protection from water attack, and the assembly into ordered arrays as well as the further construction of a series of MOF-based functional nanoarchitectures, have been realized.
      PubDate: 2018-02-22T02:16:45.292904-05:
      DOI: 10.1002/adfm.201705274
       
  • Revealing Controllable Anisotropic Magnetoresistance in Spin–Orbit
           Coupled Antiferromagnet Sr2IrO4
    • Authors: Chengliang Lu; Bin Gao, Haowen Wang, Wei Wang, Songliu Yuan, Shuai Dong, Jun-Ming Liu
      Abstract: Antiferromagnetic spintronics actively introduces new principles of magnetic memory, in which the most fundamental spin-dependent phenomena, i.e., anisotropic magnetoresistance effects, are governed by an antiferromagnet instead of a ferromagnet. A general scenario of the antiferromagnetic anisotropic magnetoresistance effects mainly stems from the magnetocrystalline anisotropy related to spin–orbit coupling. Here magnetic field driven contour rotation of the fourfold anisotropic magnetoresistance in bare antiferromagnetic Sr2IrO4/SrTiO3 (001) thin films hosting a strong spin–orbit coupling induced Jeff = 1/2 Mott state is demonstrated. Concurrently, an intriguing minimal in the magnetoresistance emerges. Through first principles calculations, the bandgap engineering due to rotation of the Ir isospins is revealed to be responsible for these emergent phenomena, different from the traditional scenario where relatively more conductive state is obtained usually when magnetic field is applied along the magnetic easy axis. These findings demonstrate a new efficient route, i.e., via the novel Jeff = 1/2 state, to realize controllable anisotropic magnetoresistance in antiferromagnetic materials.Controllable anisotropic magnetoresistance and concurrent magnetoresistance minimal are evidenced in Sr2IrO4 thin film, which is antiferromagnetic with strong spin–orbit coupling. First-principles calculations reveal that bandgap engineering due to rotation of the Ir's isospins in the films is responsible for these two emergent phenomena.
      PubDate: 2018-02-22T02:15:56.273004-05:
      DOI: 10.1002/adfm.201706589
       
  • Amplified Spontaneous Emission Based on 2D Ruddlesden–Popper
           Perovskites
    • Authors: Meili Li; Qinggang Gao, Peng Liu, Qing Liao, Haihua Zhang, Jiannian Yao, Wenping Hu, Yishi Wu, Hongbing Fu
      Abstract: 2D Ruddlesden–Popper perovskites (RPPs) are a class of quantum-well (QW) materials, composed of layered perovskite QWs encapsulated between two hydrophobic organic layers. Different from widely investigated 3D-perovskites with free carriers at room temperature, 2D-RPPs exhibit strongly bound electron–hole pairs (excitons) for high-performance solar cells and light emitting diodes (LEDs). Herein, it is reported that self-organized multiple QWs in 2D-RPP thin films naturally form an energy cascade, which enables an ultrafast energy transfer process from higher energy-bandgap QWs to lower energy-bandgap QWs. Therefore, photoexcitations are concentrated on lower-bandgap QWs, facilitating the build-up of population inversion. Room-temperature amplified spontaneous emission (ASE) from 2D-RPP thin films is achieved at dramatically low thresholds, with gain coefficients as high as>300 cm−1, and stoichiometrically tunable ASE wavelengths from visible to near-infrared spectral range (530–810 nm). In view of the high efficiency reported for LEDs, these solution-processed 2D-RPP thin films may hold the key to realize electrically driven lasers.Room-temperature amplified spontaneous emission (ASE) from thin films of 2D Ruddlesden–Popper perovskites is achieved at dramatically low thresholds, with gain coefficients as high as>300 cm−1 comparable to that reported for 3D-perovskites, and stoichiometrically tunable ASE wavelengths from visible to near-infrared spectral range.
      PubDate: 2018-02-22T02:11:50.452707-05:
      DOI: 10.1002/adfm.201707006
       
  • Metal–Organic Frameworks (MOFs)-Derived Nitrogen-Doped Porous Carbon
           Anchored on Graphene with Multifunctional Effects for Lithium–Sulfur
           Batteries
    • Authors: Ke Chen; Zhenhua Sun, Ruopian Fang, Ying Shi, Hui-Ming Cheng, Feng Li
      Abstract: Lithium–sulfur (Li–S) batteries are highly appealing for next-generation electrochemical energy storage owing to their high theoretical energy density, environmental friendliness, and low cost. However, the insulating nature of sulfur and migration of dissolved polysulfide intermediates lead to low active material utilization and fast capacity decay, which pose a significant challenge to their practical applications. Here, this paper reports a multifunctional carbon hybrid with metal–organic frameworks (MOFs)-derived nitrogen-doped porous carbon anchored on graphene sheets (NPC/G) serving as a sulfur host. On the one hand, the high surface area and nitrogen-doping of the carbon nanoparticles enable effective polysulfide immobilization through both physical confinement and chemical adsorption; on the other hand, the highly conductive graphene provides an interconnected conductive framework to facilitate fast electron transport, improving the sulfur utilization. As a result, the NPC/G-based sulfur cathode exhibits a high specific capacity of 1372 mAh g−1 with good cycling stability over 300 cycles. This approach provides a promising approach for the design of MOFs-derived carbon materials for high performance Li–S batteries.A multifunctional carbon hybrid with metal–organic frameworks-derived nitrogen-doped porous carbon in situ formed on graphene sheets is prepared for sulfur accommodation. Benefiting from the high conductivity, abundant pore structure and nitrogen doping of the carbon hybrid, the as-obtained sulfur electrode shows excellent electrochemical performance with a high specific capacity of 1372 mAh g−1 and good cycling stability over 300 cycles.
      PubDate: 2018-02-22T02:10:56.14211-05:0
      DOI: 10.1002/adfm.201707592
       
  • Redox-Stability of Alkoxy-BDT Copolymers and their Use for Organic
           Bioelectronic Devices
    • Authors: Alexander Giovannitti; Karl J. Thorley, Christian B. Nielsen, Jun Li, Mary J. Donahue, George G. Malliaras, Jonathan Rivnay, Iain McCulloch
      Abstract: Organic semiconductors can be employed as the active layer in accumulation mode organic electrochemical transistors (OECTs), where redox stability in aqueous electrolytes is important for long-term recordings of biological events. It is observed that alkoxy-benzo[1,2-b:4,5-b′]dithiophene (BDT) copolymers can be extremely unstable when they are oxidized in aqueous solutions. The redox stability of these copolymers can be improved by molecular design of the copolymer where it is observed that the electron rich comonomer 3,3′-dimethoxy-2,2′-bithiophene (MeOT2) lowers the oxidation potential and also stabilizes positive charges through delocalization and resonance effects. For copolymers where the comonomers do not have the same ability to stabilize positive charges, irreversible redox reactions are observed with the formation of quinone structures, being detrimental to performance of the materials in OECTs. Charge distribution along the copolymer from density functional theory calculations is seen to be an important factor in the stability of the charged copolymer. As a result of the stabilizing effect of the comonomer, a highly stable OECT performance is observed with transconductances in the mS range. The analysis of the decomposition pathway also raises questions about the general stability of the alkoxy-BDT unit, which is heavily used in donor–acceptor copolymers in the field of photovoltaics.The redox-stability of benzodithiophene copolymers is analyzed where it is found that copolymers with large ionization potentials (IPs) degrade during electrochemical oxidation in aqueous electrolytes while copolymers with a small IP can be charged reversibly. The degradation product is identified to be a quinone structure which has a significant impact on the performance of the copolymers in electronic devices.
      PubDate: 2018-02-21T02:12:22.643933-05:
      DOI: 10.1002/adfm.201706325
       
  • Highly Stable Plasmon Induced Hot Hole Transfer into Silicon via a SrTiO3
           Passivation Interface
    • Authors: Takayuki Matsui; Yi Li, Min-Hsiang Mark Hsu, Clement Merckling, Rupert F. Oulton, Lesley F. Cohen, Stefan A. Maier
      Abstract: Extracting plasmon-induced hot carriers over a metal–semiconductor Schottky barrier enables photodetection below the semiconductor bandgap energy. However, interfacial carrier recombination hinders the efficiency and stability of this process, severely limiting its implementation in telecommunication. This study proposes and demonstrates the use of epitaxially grown lattice-matched SrTiO3 for interfacial passivation of silicon-based plasmonic Schottky devices. The devices are activated by an electrical soft-breakdown of the interfacial SrTiO3 layer, resulting in reproducible rectified Schottky characteristics. The transition to a low resistance state of the SrTiO3 layer boosts the extraction efficiency of hot holes upon resonant plasmonic excitation, giving rise to a two orders of magnitude higher photocurrent compared to devices with a native oxide layer. Photoresponse, tunability, and barrier height studies under reverse biases as high as 100 V present superior stability with the incorporation of the SrTiO3 layer. The investigation paves the way toward plasmon-induced photodetection for practical applications including those under challenging operating conditions.A boosted near-infrared photocurrent upon resonant plasmonic excitation is reported through ultrathin perovskite SrTiO3 protected silicon-based Schottky devices. The superior stability up to 100 V and low noise level of devices under reverse biases are investigated at a soft-breakdown induced low-resistive state, outperforming conventional plasmonic hot-carrier photodetector without interfacial engineering.
      PubDate: 2018-02-21T02:11:26.398067-05:
      DOI: 10.1002/adfm.201705829
       
  • Conducting Helical Structures from Celery Decorated with a Metallic
           Conjugated Polymer Give Resonances in the Terahertz Range
    • Authors: Anders Elfwing; Carlito S. Ponseca, Liangqi Ouyang, Andrzej Urbanowicz, Aru–nas Krotkus, Deyu Tu, Robert Forchheimer, Olle Inganäs
      Abstract: A method to decorate cellulose-based helices retrieved from the plant celery with a conductive polymer is proposed. Using a layer-by-layer method, the decoration of the polyanionic conducting polymer poly(4-(2,3-dihydrothieno [3,4-b]-[1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid (PEDOT-S) is enhanced after coating the negatively charged cellulose helix with a polycationic polyethyleneimine. Microscopy techniques and two-point probe are used to image the structure and measure the conductivity of the helix. Analysis of the optical and electrical properties of the coated helix in the terahertz (THz) frequency range shows a resonance close to 1 THz and a broad shoulder that extends to 3.5 THz, consistent with electromagnetic models. Moreover, as helical antennas, it is shown that both axial and normal modes are present, which are correlated to the orientation and antenna electrical lengths of the coated helices. This work opens the possibility of designing tunable terahertz antennas through simple control of their dimensions and orientation.Using a biotemplating procedure, a conducting coil is produced from a helical bundle of celery fibers coated with a conductive polymer. The coated structure shows resonance in the terahertz region.
      PubDate: 2018-02-21T02:05:57.444716-05:
      DOI: 10.1002/adfm.201706595
       
  • Ultrasensitive and Stable Au Dimer-Based Colorimetric Sensors Using the
           Dynamically Tunable Gap-Dependent Plasmonic Coupling Optical Properties
    • Authors: Dilong Liu; Lingling Fang, Fei Zhou, Huilin Li, Tao Zhang, Cuncheng Li, Weiping Cai, Zhaoxiang Deng, Liangbin Li, Yue Li
      Abstract: A novel Au dimer-based colorimetric sensor is reported that consists of Au dimers to a chitosan hydrogel film. It utilizes the ultrasensitively gap-dependent properties of plasmonic coupling (PC) peak shift, which is associated with the dynamical tuning of the interparticle gap of the Au dimer driven by the volume swelling of the chitosan hydrogel film. The interparticle gap and PC peak shift of the Au dimer can be precisely and extensively controlled through the pH-driven volume change of chitosan hydrogel film. This colorimetric sensor exhibits a high optical sensitivity and stability, and it works in a completely reversible manner at high pH values. Importantly, the sensitivity of the composite film can be tuned by controlling the crosslinking time of the composite film, and thus leading to a wide dynamic tuning sensitive range for different applications. This presented strategy paves a way to achieve the construction of high-quality colorimetric sensors with ultrahigh sensitivity, stability and wide dynamic tuning sensitive range.A novel Au dimer-based colorimetric sensor is developed by combining an Au dimer with a smart hydrogel. This colorimetric sensor utilizes the ultrasensitively gap-dependent properties of the plasmonic coupling peak shift of the Au dimers, and thus exhibits a high optical sensitivity, stability, and wide dynamic tuning sensitive range for different applications.
      PubDate: 2018-02-21T02:02:25.603638-05:
      DOI: 10.1002/adfm.201707392
       
  • Scalable and Highly Efficient Mesoporous Wood-Based Solar Steam Generation
           Device: Localized Heat, Rapid Water Transport
    • Authors: Tian Li; He Liu, Xinpeng Zhao, Guang Chen, Jiaqi Dai, Glenn Pastel, Chao Jia, Chaoji Chen, Emily Hitz, Das Siddhartha, Ronggui Yang, Liangbing Hu
      Abstract: Solar steam generation is regarded as one of the most sustainable techniques for desalination and wastewater treatment. However, there has been a lack of scalable material systems with high efficiency under 1 Sun. A solar steam generation device is designed utilizing crossplane water transport in wood via nanoscale channels and the preferred thermal transport direction is decoupled to reduce the conductive heat loss. A high steam generation efficiency of 80% under 1 Sun and 89% under 10 Suns is achieved. Surprisingly, the crossplanes perpendicular to the mesoporous wood can provide rapid water transport via the pits and spirals. The cellulose nanofibers are circularly oriented around the pits and highly aligned along spirals to draw water across lumens. Meanwhile, the anisotropic thermal conduction of mesoporous wood is utilized, which can provide better insulation than widely used super-thermal insulator Styrofoam (≈0.03 W m−1 K−1). The crossplane direction of wood exhibits a thermal conductivity of 0.11 W m−1 K−1. The anisotropic thermal conduction redirects the absorbed heat along the in-plane direction while impeding the conductive heat loss to the water. The solar steam generation device is promising for cost-effective and large-scale application under ambient solar irradiance.A low-cost steam generation device is demonstrated with 80% conversion efficiency under 1 Sun. The heat transfer and fluidic transport directions are decouple, utilizing the mesostructure of wood. The anisotropic thermal conduction redirects the absorbed heat in-plane while impeding heat loss into bulk water. Nanoscale pits and spirals in crossplanes function as efficient water supply channels.
      PubDate: 2018-02-21T02:01:55.198026-05:
      DOI: 10.1002/adfm.201707134
       
  • Bio-inspired Highly Scattering Networks via Polymer Phase Separation
    • Authors: Julia Syurik; Gianni Jacucci, Olimpia D. Onelli, Hendrik Hölscher, Silvia Vignolini
      Abstract: A common strategy to optimize whiteness in living organisms consists in using 3D random networks with dense and polydisperse scattering elements constituted by relatively low refractive index materials. Inspired by these natural architectures, a fast and scalable method to produce highly scattering porous polymer films via phase separation is developed. By varying the molecular weight of the polymer, the morphology of the porous films is modified, and therefore their scattering properties are tuned. The achieved transport mean free paths are in the micrometer range, improving the scattering strength of analogous low refractive index systems, e.g., standard white paper, by an order of magnitude. The produced porous films show a broadband reflectivity of ≈75% while only 4 µm thick. In addition, the films are flexible and can be readily index-matched with water (i.e., they become transparent when wet), allowing for various applications such as coatings with tunable transmittance and responsive paints.Tuning the morphology of porous polymer films through a scalable phase separation process allows the tailoring of their scattering properties. The porous films show a broadband reflectivity of about 75% for a thickness of only 4 µm. In addition, the films are flexible and can be readily index-matched with water, becoming transparent when wet.
      PubDate: 2018-02-21T02:01:24.533426-05:
      DOI: 10.1002/adfm.201706901
       
  • 1 + 1>> 2: Dramatically Enhancing the Emission Efficiency of TPE-Based
           AIEgens but Keeping their Emission Color through Tailored Alkyl Linkages
    • Authors: Dongfeng Dang; Zijie Qiu, Ting Han, Yong Liu, Ming Chen, Ryan T. K. Kwok, Jacky W. Y. Lam, Ben Zhong Tang
      Abstract: Currently, the development of aggregation-induced emission (AIE) luminogens (AIEgens) has enabled us to “see” never before seen scenery. However, not all AIEgens exhibit the impressive emission efficiency in aggregated states. Moreover, the emission color of AIEgens can be seriously affected when their performance is improved. Therefore, to overcome this limitation, an efficient method is proposed here through the tailored alkyl linkages to greatly improve the emission efficiency of tetraphenylethene (TPE)-based AIEgens but retain their emission color. Encouragingly, significantly enhanced emission efficiency is achieved with the quantum yield up to 68.19% and 65.20% for BTPE-C4 and BTPE-C8, respectively, in contrast to that of TPE (25.32%), demonstrating the proverb that one plus one is much larger than two (1 + 1>> 2). Interestingly, when alkyl linkages in skeletons are fine-tuned, self-assembled nanorods, nanosheets, and nanofibers are successfully achieved for BTPE-C1, BTPE-C4, and BTPE-C8 in tetrahydrofuran and water system. Also, these developed emissive AIEgens not only exhibit impressive response to the environmental stimuli of mechanical force, viscosity, temperature, and light, but can also be used to dynamically monitor and control the phase-separated morphology in polymeric blends.To enhance the emission efficiency of tetraphenylethene-based aggregation-induced emission (AIE) luminogens (AIEgens) but retain their emission color, a facile strategy through the tailored alkyl linkages is proposed. All these developed AIEgens here exhibit impressive response to the stimuli of mechanical force, viscosity, temperature, and light, which can also be used to monitor and control the phase-separated morphology in polymeric blends.
      PubDate: 2018-02-21T01:57:07.02581-05:0
      DOI: 10.1002/adfm.201707210
       
  • DNA Computing Boosted by a Cationic Copolymer
    • Authors: Naohiko Shimada; Ken Saito, Takafumi Miyata, Hiroki Sato, Satoshi Kobayashi, Atsushi Maruyama
      Abstract: The huge information storage capability of DNA and its ability to self-assemble can be harnessed to enable massively parallel computing in a small space. DNA-based logic gates are designed that rely on DNA strand displacement reactions; however, computation is slow due to time-consuming DNA reassembly processes and prone to failure as DNA is susceptible to degradation by nucleases and under certain solution conditions. Here, it is shown that the presence of a cationic copolymer boosts the speed of DNA logic gate operations that involve multiple and parallel strand displacement reactions. Two kinds of DNA molecular operations, one based on a translator gate and one on a seesaw gate, are successfully enhanced by the copolymer without tuning of computing conditions or DNA sequences. The copolymer markedly reduces operation times from hours to minutes. Moreover, the copolymer enhances nuclease resistance.A cationic graft copolymer accelerates toehold-mediated DNA strand displacement reaction by 60-fold, and this enabled rapid operation of DNA logic gates based on the strand displacement reaction. The operation times of the DNA computer are shortened from hours to minutes by the copolymer. Moreover, the copolymer permits operation of the DNA logic gate in the presence of a nuclease.
      PubDate: 2018-02-20T03:26:56.999919-05:
      DOI: 10.1002/adfm.201707406
       
  • Unveiling the Role of Dopant Polarity in the Recombination and Performance
           of Organic Light-Emitting Diodes
    • Authors: Chang-Heon Lee; Jeong-Hwan Lee, Kwon-Hyeon Kim, Jang-Joo Kim
      Abstract: The recombination of charges is an important process in organic photonic devices, because the process influences the device characteristics such as the driving voltage, efficiency, and lifetime. Here, by using various homoleptic and heteroleptic Ir complexes as dopants, it is reported that the stationary dipole moment (μ0) of the dopant rather than the trap depth (ΔEt) is a major factor determining the recombination mechanism in dye-doped organic light-emitting diodes (OLEDs). Dopants with large μ0 (e.g., homoleptic Ir(III) dyes) induce large charge trapping on them, resulting in high driving voltage and trap-assisted recombination-dominated emission. On the other hand, dyes with small μ0 (e.g., heteroleptic Ir(III) dyes) show Langevin recombination-dominated emission characteristics with much less charge trapping on them no matter what ΔEt is, leading to lower driving voltage and higher efficiencies. This finding will be useful in any organic photonic devices such as phosphorescent or thermally assisted delayed fluorescent dye sensitized fluorescent OLEDs where trapping and recombination mechanisms play key roles.The static dipole moment of the dopant is newly suggested as dictating parameter for determining recombination mechanisms of organic light-emitting diodes. A dopant with a higher dipole moment readily captures charges, thus, trap-assisted recombination dominates over Langevin recombination in the device. This phenomenon is demonstrated experimentally and theoretically with electroluminescence measurements and a drift–diffusion model.
      PubDate: 2018-02-20T03:10:57.92778-05:0
      DOI: 10.1002/adfm.201800001
       
  • Nonhalogen Solvent-Processed Asymmetric Wide-Bandgap Polymers for
           Nonfullerene Organic Solar Cells with Over 10% Efficiency
    • Authors: Yongkang An; Xunfan Liao, Lie Chen, Jingping Yin, Qingyun Ai, Qian Xie, Bin Huang, Feng Liu, Alex K.-Y. Jen, Yiwang Chen
      Abstract: Two new wide-bandgap D–A–π copolymer donor materials, PBDT-2TC and PBDT-S-2TC, based on benzodithiophene and asymmetric bithiophene with one carboxylate (2TC) substituent are synthesized by a facile approach for fullerene-free organic solar cells (OSCs). The combination of one carboxylate-substituted thiophene with one thiophene bridge in the backbone substantially reduces the steric hindrance, thereby favoring a planar geometry for efficient charge transport and molecular packing. A reasonable highest-occupied-molecular-orbital energy level in relation to that of the acceptor and balanced hole and electron transport are observed for both polymers. This asymmetric structure unit is flexible and versatile, allowing the absorption, energy levels, and morphology of the blend films to be tailored. Fullerene-free OSCs based on PBDT-S-2TC:ITIC achieve a high power conversion efficiency of 10.12%. More impressively, a successful nonhalogen solvent-processed solar cell with 9.55% efficiency is also achieved, which is one of the highest values for a fullerene-free OSC processed using an ecofriendly solvent.New wide-bandgap D–A–π copolymers based on an asymmetric bithiophene with one carboxylate substituent were synthesized. The asymmetric structure unit is flexible and versatile, which allows the absorption, energy levels and morphology of the blend films to be adjusted easily. D-A-p copolymers produced a high power conversion efficiency of 10.0% for halogen solvent-processed OSCs and 9.55% for non-halogen solvent-processed devices.
      PubDate: 2018-02-20T03:06:40.155658-05:
      DOI: 10.1002/adfm.201706517
       
  • Holey 2D Nanosheets of Low-Valent Manganese Oxides with an Excellent
           Oxygen Catalytic Activity and a High Functionality as a Catalyst for
           Li–O2 Batteries
    • Authors: Kanyaporn Adpakpang; Seung Mi Oh, Daniel Adjei Agyeman, Xiaoyan Jin, Nutpaphat Jarulertwathana, In Young Kim, Thapanee Sarakonsri, Yong-Mook Kang, Seong-Ju Hwang
      Abstract: Holey 2D nanosheets of low-valent Mn2O3 can be synthesized by thermally induced phase transition of exfoliated layered MnO2 nanosheets. The heat treatment of layered MnO2 nanosheets at elevated temperatures leads not only to transitions to low-valent manganese oxides but also to the creation of surface hole in the 2D nanosheet crystallites. Despite distinct phase transitions, highly anisotropic 2D morphology of the precursor MnO2 material remains intact upon the heat treatment whereas the diameter of surface hole becomes larger with increasing heating temperature. The obtained holey 2D Mn2O3 nanosheets show promising electrocatalyst performances for oxygen evolution reaction, which are much superior to that of nonporous Mn2O3 crystal. Among the present materials, the holey Mn2O3 nanosheet calcined at 500 °C displays the best electrocatalyst functionality with markedly decreased overpotential, indicating the importance of heating condition in optimizing the electrocatalytic activity. Of prime importance is that this material shows much better catalytic activity for Li–O2 batteries than does nonporous Mn2O3, underscoring the critical role of porous 2D morphology in this functionality. This study clearly demonstrates the unique advantage of holey 2D nanosheet morphology in exploring economically feasible transition metal oxide-based electrocatalysts and electrodes for Li–O2 batteries.An effective synthetic route to novel holey 2D nanosheets of low-valent manganese oxides is developed by finely controlled heat treatment of exfoliated MnO2 nanosheet. The resulting holey 2D Mn2O3 nanosheets show promising functionalities as oxygen electrocatalysts and cathode catalysts for Li–O2 batteries with excellent cyclability, underscoring the remarkable advantage of holey 2D nanosheet morphology.
      PubDate: 2018-02-20T02:56:00.190319-05:
      DOI: 10.1002/adfm.201707106
       
  • Drug Carriers: Stimuli-Responsive Nucleic Acid-Based Polyacrylamide
           Hydrogel-Coated Metal–Organic Framework Nanoparticles for Controlled
           Drug Release (Adv. Funct. Mater. 8/2018)
    • Authors: Wei-Hai Chen; Wei-Ching Liao, Yang Sung Sohn, Michael Fadeev, Alessandro Cecconello, Rachel Nechushtai, Itamar Willner
      Abstract: In article number 1705137, Itamar Willner and co-workers report a new class of nano-carriers comprising stimuliresponsive hydrogel-coated metal-organic framework nanoparticles. The ATP-triggered unlocking of doxorubicin-loaded nanoparticles and the release of the drug are presented. Selective cytotoxicity and high efficiency toward MDA-MB-231 cancer cells are demonstrated.
      PubDate: 2018-02-19T05:58:28.402206-05:
      DOI: 10.1002/adfm.201870053
       
  • Masthead: (Adv. Funct. Mater. 8/2018)
    • PubDate: 2018-02-19T05:58:27.715979-05:
      DOI: 10.1002/adfm.201870050
       
  • Lithium Metal Anodes: Artificial Soft–Rigid Protective Layer for
           Dendrite-Free Lithium Metal Anode (Adv. Funct. Mater. 8/2018)
    • Authors: Rui Xu; Xue-Qiang Zhang, Xin-Bing Cheng, Hong-Jie Peng, Chen-Zi Zhao, Chong Yan, Jia-Qi Huang
      Abstract: In article number 1705838, Jia-Qi Huang and co-workers demonstrate a soft–rigid hybrid artificial protective layer for dendrite-free lithium metal anodes. The hybrid artificial protective layer can tolerate large volume fluctuations and suppress the growth of lithium dendrites during repeated lithium plating/stripping. This stratergy provides a feasible approach to improve Li metal anodes towards the application of high-energy-density lithium metal batteries.
      PubDate: 2018-02-19T05:58:25.689729-05:
      DOI: 10.1002/adfm.201870049
       
  • Actuators: Improving and Predicting Fluid Atomization via Hysteresis-Free
           Thickness Vibration of Lithium Niobate (Adv. Funct. Mater. 8/2018)
    • Authors: Sean Collignon; Ofer Manor, James Friend
      Abstract: A counterintuitively superior method for the efficient atomization of viscous fluids is described by James Friend and co-workers in article number 1704359. Hysteresis-free thickness vibration of lithium niobate is successfully implemented in a handheld nebulizer. The method could find wide-spread application in pulmonary drug delivery, mass spectrometry, and liquid chromatography.
      PubDate: 2018-02-19T05:58:25.644773-05:
      DOI: 10.1002/adfm.201870048
       
  • Electrochemical Interfaces: Potential-Specific Structure at the
           Hematite–Electrolyte Interface (Adv. Funct. Mater. 8/2018)
    • Authors: Martin E. McBriarty; Joanne E. Stubbs, Peter J. Eng, Kevin M. Rosso
      Abstract: The arrangement of water near a surface regulates the adsorption and desorption of surface species. X-ray scattering measurements presented by Martin E. McBriarty, Kevin M. Rosso, and co-workers in article number 1705618, reveal precisely how water molecules near the hematite (α-Fe2O3) surface rearrange in response to applied cathodic bias. These measurements shed new light on (photo)electrochemical reactions at oxide electrodes and mineral dissolution under far-from-equilibrium conditions.
      PubDate: 2018-02-19T05:58:20.939051-05:
      DOI: 10.1002/adfm.201870054
       
  • Contents: (Adv. Funct. Mater. 8/2018)
    • PubDate: 2018-02-19T05:58:20.776999-05:
      DOI: 10.1002/adfm.201870051
       
  • Membranes: Dopamine: Just the Right Medicine for Membranes (Adv. Funct.
           Mater. 8/2018)
    • Authors: Hao-Cheng Yang; Ruben Z. Waldman, Ming-Bang Wu, Jingwei Hou, Lin Chen, Seth B. Darling, Zhi-Kang Xu
      Abstract: In article number 1705327, Seth B. Darling, Zhi-Kang Xu, and co-workers describe how mussel-inspired chemistry, based on polydopamine coatings, is poised to revolutionize the field of membrane science. Interface engineering mediated by polydopamine enables enormous flexibility in tuning surface properties—largely independent of the native properties of the starting membrane material.
      PubDate: 2018-02-19T05:58:20.720857-05:
      DOI: 10.1002/adfm.201870052
       
  • Phase-Modulated Band Alignment in CdS Nanorod/SnSx Nanosheet Hierarchical
           Heterojunctions toward Efficient Water Splitting
    • Authors: Yanming Fu; Fengren Cao, Fangli Wu, Zhidan Diao, Jie Chen, Shaohua Shen, Liang Li
      Abstract: CdS is a promising visible light response photoanode of photoelectrochemical (PEC) water splitting, but it remains a great challenge for practical application, due to the photohole-induced self-corrosion, and sulfide/sulfite ions as hole scavengers are always necessary for stable solar hydrogen generation. Herein, a CdS/SnSx nanorods/nanosheets hierarchical heterostructure with novel phase-engineered band alignment is rationally designed via a two-step solution reaction route for PEC water splitting. In the Na2SO4 aqueous electrolyte without any hole scavengers, compared with the pristine CdS, the CdS/SnSx photoanode achieves a remarkably enhanced photocurrent density of 1.59 mA cm−2 and a considerable stability at bias potential 1.23 V versus reversible hydrogen electrode (RHE) under simulated sunlight. It is proposed that the deposited SnSx nanosheets not only act as protective layers to restrain the photocorrosion of CdS, but also facilitate the charge separation in CdS by the virtue of the Type II heterojunction formed between CdS and SnSx.CdS/SnSx 1D/2D hierarchical heterostructure photoanodes are successfully constructed via a two-step process and rationally improved with engineered band alignment by tuning the crystal phase of SnSx. Compared with pristine CdS, the optimal heterostructure achieves a greatly enhanced photocurrent density of 1.59 mA cm−2 with considerable stability in neutral Na2SO4 aqueous electrolyte without any hole scavengers.
      PubDate: 2018-02-19T03:07:08.504097-05:
      DOI: 10.1002/adfm.201706785
       
  • Ultrathin 2D Nonlayered Tellurium Nanosheets: Facile Liquid-Phase
           Exfoliation, Characterization, and Photoresponse with High Performance and
           Enhanced Stability
    • Authors: Zhongjian Xie; Chenyang Xing, Weichun Huang, Taojian Fan, Zhongjun Li, Jinlai Zhao, Yuanjiang Xiang, Zhinan Guo, Jianqing Li, Zhigang Yang, Biqing Dong, Junle Qu, Dianyuan Fan, Han Zhang
      Abstract: Nonlayered materials are constructed with chemical covalent bonds in all three dimensions, distinct from layered materials, which contain evident structural differences in the horizontal and vertical directions. As a consequence, liquid-phase exfoliation (LPE), a widely explored technique to obtain 2D layered nanoarchitectures, has not yet been fully characterized for the realization of 2D nonlayered nanostructures. Herein, by virtue of a typical chain-like structure of crystalline bulk Te with strong TeTe covalent bonds in intrachains and weak Van der Waals forces in interchains, ultrathin 2D nonlayered Te nanosheets are realized by means of an LPE method. The resultant 2D Te nanosheets possess a broad lateral dimension ranging from 41.5 to 177.5 nm and a thickness ranging from 5.1 to 6.4 nm, and its photoresponse properties are evaluated using photoelectrochemical measurements. The 2D Te nanosheets exhibit excellent photoresponse behaviors from the UV to the visible regime in association with strong time and cycle stability for the on/off switching behaviors. The fabrication approach of 2D Te nanosheets would arouse interest in exfoliating other nonlayered 2D materials, which would expand the family of 2D materials.2D nonlayered tellurium (Te) nanosheets are successfully exfoliated using liquid-phase exfoliation. The obtained 2D Te nanosheets exhibit excellent photoresponse behavior from the UV to the visible regime in association with strong time and cycle stability. The facile fabrication approach of 2D Te nanosheets would arouse interest in exfoliating other nonlayered 2D materials, which would expand the family of 2D materials.
      PubDate: 2018-02-19T03:05:25.919482-05:
      DOI: 10.1002/adfm.201705833
       
  • Direct 3D Printing of Ultralight Graphene Oxide Aerogel Microlattices
    • Authors: Yanqiu Jiang; Zhen Xu, Tieqi Huang, Yingjun Liu, Fan Guo, Jiabin Xi, Weiwei Gao, Chao Gao
      Abstract: Graphene aerogel microlattices (GAMs) hold great prospects for many multifunctional applications due to their low density, high porosity, designed lattice structures, good elasticity, and tunable electrical conductivity. Previous 3D printing approaches to fabricate GAMs require either high content of additives or complex processes, limiting their wide applications. Here, a facile ion-induced gelation method is demonstrated to directly print GAMs from graphene oxide (GO) based ink. With trace addition of Ca2+ ions as gelators, aqueous GO sol converts to printable gel ink. Self-standing 3D structures with programmable microlattices are directly printed just in air at room temperature. The rich hierarchical pores and high electrical conductivity of GAMs bring admirable capacitive performance for supercapacitors. The gravimetric capacitance (Cs) of GAMs is 213 F g−1 at 0.5 A g−1 and 183 F g−1 at 100 A g−1, and retains over 90% after 50 000 cycles. The facile, direct 3D printing of neat graphene oxide can promote wide applications of GAMs from energy storage to tissue engineering scaffolds.Ultralight neat graphene aerogel microlattices (GAMs) with 3D geometric structure are fabricated via an ion-induced gelation 3D printing method. The printed GAMs display rich hierarchical pores and high electrical conductivity, affording GAMs outstanding capacitive performance as supercapacitors. The facile, direct 3D printing strategy opens an avenue to wide applications of GAMs.
      PubDate: 2018-02-19T02:54:59.251463-05:
      DOI: 10.1002/adfm.201707024
       
  • Centimeter-Sized Cs4PbBr6 Crystals with Embedded CsPbBr3 Nanocrystals
           Showing Superior Photoluminescence: Nonstoichiometry Induced
           Transformation and Light-Emitting Applications
    • Authors: Xiaomei Chen; Feng Zhang, Yong Ge, Lifu Shi, Sheng Huang, Jialun Tang, Zhao Lv, Li Zhang, Bingsuo Zou, Haizheng Zhong
      Abstract: An HBr-assisted slow cooling method is developed for the growth of centimeter-sized Cs4PbBr6 crystals. The obtained crystals show strong green photoluminescence with absolute photoluminescence quantum yields up to 97%. More importantly, the evolution process and structural characterizations support that the nonstoichiometry of initial Cs4PbBr6 crystals induce the formation of nanosized CsPbBr3 nanocrystals in crystalline Cs4PbBr6 matrices. Furthermore, high efficiency and wide color gamut prototype white light-emitting diode devices are also demonstrated by combining the highly luminescent Cs4PbBr6 crystals as green emitters and commercial K2SiF6:Mn4+ phosphor as red emitters with blue emitting GaN chips. The optimized devices generate high-quality white light with luminous efficiency of ≈151 lm W−1 and color gamut of 90.6% Rec. 2020 at 20 mA, which is much better than that based on conventional perovskite nanocrystals. The combination of improved efficiency and better stability with comparable color quality provides an alternative choice for liquid crystal display backlights.Centimeter-sized Cs4PbBr6 crystals with embedded CsPbBr3 NCs are fabricated through an HBr-assisted slow cooling technique, achieving a photoluminescence quantum yield about 97%. The formation can be explained by the nonstoichiometry induced partial transformation from defective Cs4PbBr6 crystals. Furthermore, a luminous efficiency up to 151 lm W−1 with a color gamut of 90.6% of Rec. 2020 is achieved, showing the bright future for display backlights.
      PubDate: 2018-02-19T02:54:33.823426-05:
      DOI: 10.1002/adfm.201706567
       
  • Toward Optimal Performance and In-Depth Understanding of Spinel Li4Ti5O12
           Electrodes through Phase Field Modeling
    • Authors: Alexandros Vasileiadis; Niek J. J. de Klerk, Raymond B. Smith, Swapna Ganapathy, Peter Paul R. M. L. Harks, Martin Z. Bazant, Marnix Wagemaker
      Abstract: Computational modeling is vital for the fundamental understanding of processes in Li-ion batteries. However, capturing nanoscopic to mesoscopic phase thermodynamics and kinetics in the solid electrode particles embedded in realistic electrode morphologies is challenging. In particular for electrode materials displaying a first order phase transition, such as LiFePO4, graphite, and spinel Li4Ti5O12, predicting the macroscopic electrochemical behavior requires an accurate physical model. Herein, a thermodynamic phase field model is presented for Li-ion insertion in spinel Li4Ti5O12 which captures the performance limitations presented in literature as a function of all relevant electrode parameters. The phase stability in the model is based on ab initio density functional theory calculations and the Li-ion diffusion parameters on nanoscopic nuclear magnetic resonance (NMR) measurements of Li-ion mobility, resulting in a parameter free model. The direct comparison with prepared electrodes shows good agreement over three orders of magnitude in the discharge current. Overpotentials associated with the various charge transport processes, as well as the active particle fraction relevant for local hotspots in batteries, are analyzed. It is demonstrated which process limits the electrode performance under a variety of realistic conditions, providing comprehensive understanding of the nanoscopic to microscopic properties. These results provide concrete directions toward the design of optimally performing Li4Ti5O12 electrodes.Herein, the phase separation is computationally captured upon lithiation of spinel Li4Ti5O12 electrodes via a thermodynamic phase field model that incorporates nanoscopic phase thermodynamics measured with density functional theory. Thus, it is able to bridge nanoscopic to mesoscopic modeling, alleviate fitted parameters, and provide guidelines for optimized performance.
      PubDate: 2018-02-19T02:53:19.297528-05:
      DOI: 10.1002/adfm.201705992
       
  • Molybdenum Phosphide/Carbon Nanotube Hybrids as pH-Universal
           Electrocatalysts for Hydrogen Evolution Reaction
    • Authors: Xing Zhang; Xiaolu Yu, Linjie Zhang, Feng Zhou, Yongye Liang, Ruihu Wang
      Abstract: Molybdenum phosphide (MoP) has received increasing attention due to its high catalytic activity in hydrogen evolution reaction (HER). However, it remains difficult to construct well-defined MoP nanostructures with large density of active sites and high intrinsic activity. Here, a facile and general method is reported to synthesize an MoP/carbon nanotube (CNT) hybrid featuring small-sized and well-crystallized MoP nanoparticles uniformly coated on the sidewalls of multiwalled CNT. The MoP/CNT hybrid exhibits impressive HER activities in pH-universal electrolytes, and requires the overpotentials as low as 83, 102, and 86 mV to achieve a cathodic current density of 10 mA cm−2 in acidic 0.5 m H2SO4, neutral 1 m phosphate buffer solution, and alkaline 1 m KOH electrolytes, respectively. It is found that the crystallinity of MoP has significant influence on HER activity. This study provides a new design strategy to construct MoP nanostructures for optimizing its catalytic performance.Molybdenum phosphide (MoP)/carbon nanotube (CNT) hybrids, featuring small and well-crystallized MoP nanocrystals uniformly coated on CNT sidewalls, have been constructed through a facile two-step synthetic strategy. Benefiting from high intrinsic activity and large density of accessible active sites on MoP, the hybrids exhibit impressive hydrogen evolution reaction catalytic activities and stabilities in pH-universal electrolytes.
      PubDate: 2018-02-19T02:50:46.12229-05:0
      DOI: 10.1002/adfm.201706523
       
  • Tumor-Specific Self-Degradable Nanogels as Potential Carriers for Systemic
           Delivery of Anticancer Proteins
    • Authors: Qiuwen Zhu; Xiaojie Chen, Xiao Xu, Ying Zhang, Can Zhang, Ran Mo
      Abstract: Development of a safe and effective carrier for systemic protein delivery is highly desirable, which depends on management of the relationship among loading capacity, stability, delivery efficiency, and degradability. Here, a tumor-specific self-degradable nanogel composed of hyaluronidase (HAase)-degradable hyaluronic acid (HA) matrices entrapping acid-activatable HAase (aHAase) for systemic delivery of anticancer proteins is reported. Collaboratively crosslinked nanogels (cNG) obtained by the synthetic cholesteryl methacrylated HA show high protein-loading capacity and stability. The aHAase is engineered by modifying the HAase with citraconic anhydride to shield its HA-degrading activity, which can be reversibly activated by hydrolysis of the citraconic amide under acidic condition. In the tumor microenvironment, the mild acidity activates the aHAase partially, which results in swelling of the cNG and releasing of the aHAase. The released reactivated aHAase can degrade the HA that is also a major constituent of tumor extracellular matrix to increase perfusion of the cNG in the tumor stroma. In the acidic endocytic vesicles, the aHAase is fully reactivated. The active aHAase completely degrades the cNG to release the encapsulated anticancer protein, deoxyribonuclease I intracellularly, which digests the DNA to cause tumor cell death for enhanced antitumor efficacy.A collaboratively-crosslinked hyaluronic acid-based nanogel is developed with a high loading capacity for a variety of proteins and a favorable stability against plasma proteins. Equipped with acid-activatable hyaluronidase, the nanogel possesses tumor-acidity-induced self-degradability, which enables a programmable cascade delivery of anticancer protein for enhanced cancer therapy.
      PubDate: 2018-02-19T02:48:32.652108-05:
      DOI: 10.1002/adfm.201707371
       
  • Ultralong Room-Temperature Phosphorescence from Amorphous Polymer
           Poly(Styrene Sulfonic Acid) in Air in the Dry Solid State
    • Authors: Tomoki Ogoshi; Hiromu Tsuchida, Takahiro Kakuta, Tada-aki Yamagishi, Ai Taema, Toshikazu Ono, Manabu Sugimoto, Motohiro Mizuno
      Abstract: Polymer-based room-temperature-phosphorescent (RTP) materials are attractive alternatives to low-molecular-weight organic RTP compounds because they can form self-standing transparent films with high thermal stability. However, their RTP lifetimes in air are usually short (
      PubDate: 2018-02-19T02:47:37.87146-05:0
      DOI: 10.1002/adfm.201707369
       
  • Evidence that Crystal Facet Orientation Dictates Oxygen Evolution
           Intermediates on Rutile Manganese Oxide
    • Authors: Hirotaka Kakizaki; Hideshi Ooka, Toru Hayashi, Akira Yamaguchi, Nadège Bonnet-Mercier, Kazuhito Hashimoto, Ryuhei Nakamura
      Abstract: Elucidating the mechanism that differentiates the oxygen-evolving center of photosystem II with its inorganic counterpart is crucial to develop efficient catalysts for the oxygen evolution reaction (OER). Previous studies have suggested that the larger overpotential for MnO2 catalysts under neutral conditions may result from the instability of the Mn3+ intermediate to charge disproportionation. Here, by monitoring the surface intermediates of electrochemical OER on rutile MnO2 with different facet orientations, a correlation between the stability of the intermediate species and crystal facets is confirmed explicitly for the first time. The coverage of the Mn3+ intermediate is found to be 11-fold higher on the metastable (101) surfaces compared to (110) surfaces, leading to the superior OER activity of (101) surfaces. The difference in OER activity may result from the difference in surface electronic states of Mn3+, where interlayer charge comproportionation of Mn2+ and Mn4+ to generate two Mn3+ species is favored on (101) facets. Considering the fact that the OER enzyme accommodates Mn3+ stably during the Kok cycle, the enhanced OER activity of the rutile MnO2 catalyst with a metastable surface highlights the importance of mimicking not only the crystal structure but also the electronic structure of the targeted natural enzyme.The oxygen evolution activity of MnO2 with different facet orientations is studied to gain insight into the role of Mn3+ and allow for the rational design of functional analogs of the biological oxygen evolution center. (101) surfaces display higher activity compared to (110) surfaces despite having the same bulk crystal structure, due to the increased stabilization of Mn3+ on (101).
      PubDate: 2018-02-16T02:01:13.329528-05:
      DOI: 10.1002/adfm.201706319
       
  • Tuning the Electronic and Photonic Properties of Monolayer MoS2 via In
           Situ Rhenium Substitutional Doping
    • Authors: Kehao Zhang; Brian M. Bersch, Jaydeep Joshi, Rafik Addou, Christopher R. Cormier, Chenxi Zhang, Ke Xu, Natalie C. Briggs, Ke Wang, Shruti Subramanian, Kyeongjae Cho, Susan Fullerton-Shirey, Robert M. Wallace, Patrick M. Vora, Joshua A. Robinson
      Abstract: Doping is a fundamental requirement for tuning and improving the properties of conventional semiconductors. Recent doping studies including niobium (Nb) doping of molybdenum disulfide (MoS2) and tungsten (W) doping of molybdenum diselenide (MoSe2) have suggested that substitutional doping may provide an efficient route to tune the doping type and suppress deep trap levels of 2D materials. To date, the impact of the doping on the structural, electronic, and photonic properties of in situ-doped monolayers remains unanswered due to challenges including strong film substrate charge transfer, and difficulty achieving doping concentrations greater than 0.3 at%. Here, in situ rhenium (Re) doping of synthetic monolayer MoS2 with ≈1 at% Re is demonstrated. To limit substrate film charge transfer, r-plane sapphire is used. Electronic measurements demonstrate that 1 at% Re doping achieves nearly degenerate n-type doping, which agrees with density functional theory calculations. Moreover, low-temperature photoluminescence indicates a significant quench of the defect-bound emission when Re is introduced, which is attributed to the MoO bond and sulfur vacancies passivation and reduction in gap states due to the presence of Re. The work presented here demonstrates that Re doping of MoS2 is a promising route toward electronic and photonic engineering of 2D materials.This work demonstrates in situ rhenium (Re) doping of synthetic monolayer MoS2 with ≈1 at% Re on r-plane sapphire. Electronic measurements elucidate that 1 at% Re doping achieves nearly degenerate n-type doping, which agrees with density functional theory calculations. Low-temperature photoluminescence measurements reveal suppression of defect emission induced by Re doping, resulting from the passivation of defects due to the presence of Re.
      PubDate: 2018-02-16T01:50:48.805385-05:
      DOI: 10.1002/adfm.201706950
       
  • Highly In-Plane Optical and Electrical Anisotropy of 2D Germanium Arsenide
    • Authors: Shengxue Yang; Yanhan Yang, Minghui Wu, Chunguang Hu, Wanfu Shen, Yongji Gong, Li Huang, Chengbao Jiang, Yongzhe Zhang, Pulickel M. Ajayan
      Abstract: Anisotropic 2D materials exhibit unique optical, electrical, and thermoelectric properties that open up possibilities for diverse angle-dependent devices. However, the explored anisotropic 2D materials are very limited and the methods to identify the crystal orientations and to study the in-plane anisotropy are in the initial stage. Here azimuth-dependent reflectance difference microscopy (ADRDM), angle-resolved Raman spectra, and electrical transport measurements are used to systematically characterize the influence of the anisotropic structure on in-plane optical and electrical anisotropy of 2D GeAs, a novel group IV–V semiconductor. It is proved that ADRDM offers a way to quickly identify the crystal orientations and also to directly characterize the in-plane optical anisotropy of layered GeAs. The anisotropic electrical transport behavior of few-layer GeAs field-effect transistors is further measured and the anisotropic ratio of the mobility is as high as 4.6, which is higher than the other 2D anisotropic materials such as black phosphorus. The dependence of the Raman intensity anisotropy on the sample thickness, excitation wavelength, and polarization configuration is investigated both experimentally and theoretically. These data will be useful for designing new high-performance devices and the results suggest a general methodology for characterizing the in-plane anisotropy of low-symmetry 2D materials.Here the in-plane anisotropic optical and electrical properties of low-symmetry 2D layered GeAs are reported by combining the polarized Raman spectra, azimuth-dependent reflectance difference microscopy, and angle-resolved electrical transport measurements with related theoretical calculations.
      PubDate: 2018-02-16T01:48:02.31831-05:0
      DOI: 10.1002/adfm.201707379
       
  • A General Metal-Organic Framework (MOF)-Derived Selenidation Strategy for
           In Situ Carbon-Encapsulated Metal Selenides as High-Rate Anodes for Na-Ion
           Batteries
    • Authors: Xijun Xu; Jun Liu, Jiangwen Liu, Liuzhang Ouyang, Renzong Hu, Hui Wang, Lichun Yang, Min Zhu
      Abstract: On account of increasing demand for energy storage devices, sodium-ion batteries (SIBs) with abundant reserve, low cost, and similar electrochemical properties have the potential to partly replace the commercial lithium-ion batteries. In this study, a facile metal-organic framework (MOF)-derived selenidation strategy to synthesize in situ carbon-encapsulated selenides as superior anode for SIBs is rationally designed. These selenides with particular micro- and nanostructured features deliver ultrastable cycling performance at high charge–discharge rate and demonstrate ultraexcellent rate capability. For example, the uniform peapod-like Fe7Se8@C nanorods represent a high specific capacity of 218 mAh g−1 after 500 cycles at 3 A g−1 and the porous NiSe@C spheres display a high specific capacity of 160 mAh g−1 after 2000 cycles at 3 A g−1. The current simple MOF-derived method could be a promising strategy for boosting the development of new functional inorganic materials for energy storage, catalysis, and sensors.Carbon-encapsulated metal selenide electrodes with multiscale, multidimensional, and hierarchical architectures are successfully designed and synthesized via a general and facile metal-organic framework derived selenidation strategy. Due to the novel and unique architecture design, these nanohybrid electrodes display ultrastable cycling performance as well as excellent rate capability for Na-ion batteries.
      PubDate: 2018-02-16T01:46:20.684645-05:
      DOI: 10.1002/adfm.201707573
       
  • Fast, Self-Driven, Air-Stable, and Broadband Photodetector Based on
           Vertically Aligned PtSe2/GaAs Heterojunction
    • Authors: Long-Hui Zeng; Sheng-Huang Lin, Zhong-Jun Li, Zhi-Xiang Zhang, Teng-Fei Zhang, Chao Xie, Chun-Hin Mak, Yang Chai, Shu Ping Lau, Lin-Bao Luo, Yuen Hong Tsang
      Abstract: Group-10 layered transitional metal dichalcogenides including PtS2, PtSe2, and PtTe2 are excellent potential candidates for optoelectronic devices due to their unique properties such as high carrier mobility, tunable bandgap, stability, and flexibility. Large-area platinum diselenide (PtSe2) with semiconducting characteristics is far scarcely investigated. Here, the development of a high-performance photodetector based on vertically aligned PtSe2-GaAs heterojunction which exhibits a broadband sensitivity from deep ultraviolet to near-infrared light, with peak sensitivity from 650 to 810 nm, is reported. The Ilight/Idark ratio and responsivity of photodetector are 3 × 104 and 262 mA W−1 measured at 808 nm under zero bias voltage. The response speed of τr/τf is 5.5/6.5 µs, which represents the best result achieved for Group-10 TMDs based optoelectronic device thus far. According to first-principle density functional theory, the broad photoresponse ranging from visible to near-infrared region is associated with the semiconducting characteristics of PtSe2 which has interstitial Se atoms within the PtSe2 layers. It is also revealed that the PtSe2/GaAs photodetector does not exhibit performance degradation after six weeks in air. The generality of the above good results suggests that the vertically aligned PtSe2 is an ideal material for high-performance optoelectronic systems in the future.This work shows the large-area growth of high-quality vertically aligned PtSe2, and its application to photodetectors based on PtSe2-GaAs heterojunctions which exhibit a broadband sensitivity to illumination ranging from deep ultraviolet to near-infrared light, with a peak sensitivity in the region from 650 to 810 nm. The high-performance broadband photodetector will develop the next-generation 2D Group-10 materials based optoelectronic devices.
      PubDate: 2018-02-16T01:41:48.709881-05:
      DOI: 10.1002/adfm.201705970
       
  • CdS Nanoribbon-Based Resistive Switches with Ultrawidely Tunable Power by
           Surface Charge Transfer Doping
    • Authors: Zhibin Shao; Jiansheng Jie, Tianhao Jiang, Xiaofeng Wu, Ke Li, Feifei Xia, Xiujuan Zhang, Xiaohong Zhang
      Abstract: Traditional metal–insulator–metal (MIM)-based resistive switches (RS) possess a high operating current, which can be read directly without an amplifier yet will inevitably produce large power consumption. Rational control of the energy consumption of RS devices is surely desirable to achieve the energy-efficient purpose in a variety of practical applications. Here a surface charge transfer doping (SCTD) strategy is reported to manipulate the operating current as well as power consumption of the RS devices by using doped CdS nanoribbon (NR) as a rheostat. By controlling the concentration of surface dopant of MoO3, the conductivity of doped CdS NR can be tuned in a wide range of nine orders of magnitude, showing the transition from insulator to semiconductor and to conductor. On the basis of CdS NRs with controllable conductivity, the as-fabricated RS devices exhibit an ultrawidely tunable-power consumption from 1 nW, the lowest value reported so far, to 0.1 mW, which is close to the typical values of MIM-based RS devices. In view of the high controllability of the SCTD method, this work opens up unique opportunities for future energy-efficient, performance-tunable, and multifunctional RS devices based on semiconductor nanostructures.Ultrawidely power-tunable resistive switching (RS) devices based on CdS nanoribbons are constructed via a surface charge transfer doping method. The doped CdS nanoribbons can serve as a rheostat in RS devices to adjust the power consumption from 1 nW to 0.1 mW, thus opening up unique opportunities for future energy-efficient, performance-tunable, and multifunctional RS devices based on semiconductor nanostructures.
      PubDate: 2018-02-15T03:42:39.95649-05:0
      DOI: 10.1002/adfm.201706577
       
  • Cilia-Inspired Flexible Arrays for Intelligent Transport of Viscoelastic
           Microspheres
    • Authors: Shuang Ben; Jun Tai, Han Ma, Yun Peng, Yuan Zhang, Dongliang Tian, Kesong Liu, Lei Jiang
      Abstract: Anisotropic microstructures are widely used by being cleverly designed to achieve important functions. Mammals' respiratory tract is filled with dense cilia that rhythmically swing back and forth in a unidirectional wave to propel mucus and harmful substances out of the lung through larynx. Inspired by the ciliary structure and motion mechanism of the respiratory tract systems, a viscoelastic microsphere transporting strategy based on integration of airway cilium-like structure and magnetically responsive flexible conical arrays is demonstrated. Under external magnetic fields, the viscoelastic microspheres can be directionally and continuously transported alongside the swing of the cilia-like arrays that contain magnetic particles. This work provides a promising route for the design of advanced medical applications in directional transport of microspheres, drug delivery systems, ciliary dyskinesia treating, and self-cleaning without liquid.A magnetically induced viscoelastic microsphere transporting device is designed and fabricated through the integration of cilia-inspired magnetically responsive flexible arrays. Under external magnetic field, microparticles can be continuously and directionally transported through the periodic vibration of flexible arrays. This work opens a new avenue for directional transport of microspheres, drug delivery systems, treatment of ciliary dyskinesia, and self-cleaning without a liquid.
      PubDate: 2018-02-15T03:41:42.450961-05:
      DOI: 10.1002/adfm.201706666
       
  • Reduced Graphene Oxide as a Catalyst Binder: Greatly Enhanced
           Photoelectrochemical Stability of Cu(In,Ga)Se2 Photocathode for Solar
           Water Splitting
    • Authors: Bonhyeong Koo; Segi Byun, Sung-Wook Nam, Song-Yi Moon, Suncheul Kim, Jeong Young Park, Byung Tae Ahn, Byungha Shin
      Abstract: The photoelectrochemical (PEC) properties of a Cu(In,Ga)Se2 (CIGS) photocathode covered with reduced graphene oxide (rGO) as a catalyst binder for solar-driven hydrogen evolution are reported. Chemically reduced rGO with various concentrations is deposited as an adhesive interlayer between CIGS/CdS and Pt. PEC characteristics of the CIGS/CdS/rGO/Pt are improved compared to the photocathode without rGO due to enhancement of charge transfer via efficient lateral distribution of photogenerated electrons by conductive rGO to the Pt. More importantly, the introduction of rGO to the CIGS photocathode significantly enhances the PEC stability; in the absence of rGO, a rapid loss of PEC stability is observed in 2.5 h, while the optimal rGO increases the PEC stability of the CIGS photocathode for more than 7 h. Chemical and structural characterizations show that the loss of the Pt catalyst is one of the main reasons for the lack of long-term PEC stability; the introduction of rGO, which acts as a binder to the Pt catalysts by providing anchoring sites in the rGO, results in complete conservation of the Pt and hence much enhanced stability. Multiple functionality of rGO as an adhesive interlayer, an efficient charge transport layer, a diffusion barrier, and protection layer is demonstrated.Photoelectrochemical (PEC) stability of a Cu(In,Ga)Se2 (CIGS) photocathode with reduced graphene oxide (rGO) as a catalyst binder is evaluated. The introduction of the rGO between the CIGS/CdS and the Pt catalyst improves the PEC stability more than three times by suppressing agglomeration of Pt electrocatalysts, desorption into an electrolyte, and in-diffusion to the CdS buffer layer.
      PubDate: 2018-02-15T03:40:57.953549-05:
      DOI: 10.1002/adfm.201705136
       
  • Fast and Accurate Imaging of Lymph Node Metastasis with Multifunctional
           Near-Infrared Polymer Dots
    • Authors: Fengwen Cao; Yixiao Guo, Yao Li, Shiyi Tang, Yidian Yang, Hong Yang, Liqin Xiong
      Abstract: Metastasis to regional lymph nodes is a significant prognostic indicator for cancer progression. There is a great demand for rapid and accurate diagnosis of metastasis to the lymph nodes. In this work, folate receptor-targeted trimodal polymer dots are designed for near-infrared (NIR)/photoacoustic (PA)/magnetic resonance (MR) imaging of lymph node metastasis. Confocal microscopic analyses and flow cytometry show that pulmonary mucosa epithelial cell carcinoma NCI-H292 with expression of the folate receptor is positive for folate-functional polymer dots. In vivo and ex vivo NIR imaging results verify that prepared polymer dots show rapid and high uptake in the metastatic lymph nodes, can effectively distinguish metastatic and normal lymph nodes for 1 h postinjection, and have great potential in real-time imaging-guided surgery. Furthermore, ten metastatic lymph nodes from the tumor-bearing mice are detected by NIR imaging via intratumoral injection of polymer dots. Moreover, in vivo PA and MR imaging confirm the enhanced PA and MR signals of polymer dots in the metastatic lymph nodes as well as enlarged lymph nodes in tumor-bearing mice. The results of this study provide a unique approach using trimodal polymer dots for the rapid and precise diagnosis of lymph node metastasis in vivo.Trimodal near-infrared/photoacoustic/magnetic resonance polymer dots are prepared by the one-pot reprecipitation method, and demonstrated to be capable of the fast and accurate imaging of lymph nodes metastasis in tumor-bearing mice and photodynamic therapy.
      PubDate: 2018-02-15T03:24:57.07381-05:0
      DOI: 10.1002/adfm.201707174
       
  • Thin Film Condensation on Nanostructured Surfaces
    • Authors: Junho Oh; Runyu Zhang, Pralav P. Shetty, Jessica A. Krogstad, Paul V. Braun, Nenad Miljkovic
      Abstract: Water vapor condensation is a ubiquitous process in nature and industry. Over the past century, methods achieving dropwise condensation using a thin (
      PubDate: 2018-02-15T03:23:24.757419-05:
      DOI: 10.1002/adfm.201707000
       
  • Protoporphyrin IX (PpIX)-Coated Superparamagnetic Iron Oxide Nanoparticle
           (SPION) Nanoclusters for Magnetic Resonance Imaging and Photodynamic
           Therapy
    • Authors: Lesan Yan; Ahmad Amirshaghaghi, Dennis Huang, Joann Miller, Joel M. Stein, Theresa M. Busch, Zhiliang Cheng, Andrew Tsourkas
      Abstract: The ability to produce nanotherapeutics at large-scale with high drug loading efficiency, high drug loading capacity, high stability, and high potency is critical for clinical translation. However, many nanoparticle-based therapeutics under investigation suffer from complicated synthesis, poor reproducibility, low stability, and high cost. In this work, a simple method for preparing multifunctional nanoparticles is utilized that act as both a contrast agent for magnetic resonance imaging and a photosensitizer for photodynamic therapy for the treatment of cancer. In particular, the photosensitizer protoporphyrin IX (PpIX) is used to solubilize small nanoclusters of superparamagnetic iron oxide nanoparticles (SPIONs) without the use of any additional carrier materials. These nanoclusters are characterized with a high PpIX loading efficiency; a high loading capacity, stable behavior; high potency; and a synthetic approach that is amenable to large-scale production. In vivo studies of photodynamic therapy (PDT) efficacy show that the PpIX-coated SPION nanoclusters lead to a significant reduction in the growth rate of tumors in a syngeneic murine tumor model compared to both free PpIX and PpIX-loaded poly(ethylene glycol)-polycaprolactone micelles, even when injected at 1/8th the dose. These results suggest that the nanoclusters developed in this work can be a promising nanotherapeutic for clinical translation.A simple method for preparing multifunctional nanoparticles that act as both a contrast agent for magnetic resonance imaging and a photosensitizer for photodynamic therapy is developed. These nanoparticles lead to a significant reduction in the growth rate of tumors compared to both free protoporphyrin IX (PpIX) and PpIX-loaded micelles, even when injected at 1/8th the dose.
      PubDate: 2018-02-15T03:22:15.178834-05:
      DOI: 10.1002/adfm.201707030
       
  • Hydrodynamically Guided Hierarchical Self-Assembly of
           Peptide–Protein Bioinks
    • Authors: Clara L. Hedegaard; Estelle C. Collin, Carlos Redondo-Gómez, Luong T. H. Nguyen, Kee Woei Ng, Alfonso A. Castrejón-Pita, J. Rafael Castrejón-Pita, Alvaro Mata
      Abstract: Effective integration of molecular self-assembly and additive manufacturing would provide a technological leap in bioprinting. This article reports on a biofabrication system based on the hydrodynamically guided co-assembly of peptide amphiphiles (PAs) with naturally occurring biomolecules and proteins to generate hierarchical constructs with tuneable molecular composition and structural control. The system takes advantage of droplet-on-demand inkjet printing to exploit interfacial fluid forces and guide molecular self-assembly into aligned or disordered nanofibers, hydrogel structures of different geometries and sizes, surface topographies, and higher-ordered constructs bound by molecular diffusion. PAs are designed to co-assemble during printing in cell diluent conditions with a range of extracellular matrix (ECM) proteins and biomolecules including fibronectin, collagen, keratin, elastin-like proteins, and hyaluronic acid. Using combinations of these molecules, NIH-3T3 and adipose derived stem cells are bioprinted within complex structures while exhibiting high cell viability (>88%). By integrating self-assembly with 3D-bioprinting, the study introduces a novel biofabrication platform capable of encapsulating and spatially distributing multiple cell types within tuneable pericellular environments. In this way, the work demonstrates the potential of the approach to generate complex bioactive scaffolds for applications such as tissue engineering, in vitro models, and drug screening.Bridging the gap between advanced biomaterials and biofabrication. A novel bioink whereby peptide amphiphiles are used as “chaperones” to organize extracellular matrix proteins and biomolecules into hierarchical structures. The method takes advantage of interfacial forces generated between solutions of the co-assembling molecules enabling the possibility to bioprint while controlling biomolecular and structural elements of the printed scaffold.
      PubDate: 2018-02-15T02:00:04.97899-05:0
      DOI: 10.1002/adfm.201703716
       
  • Nanoscale Zr-Based MOFs with Tailorable Size and Introduced Mesopore for
           Protein Delivery
    • Authors: Zhe Wang; Shuanggang Hu, Jian Yang, Ajuan Liang, Yongsheng Li, Qixin Zhuang, Jinlou Gu
      Abstract: Introduction of large pore in the primitive microporous metal–organic frameworks (MOFs) with tailorable particle size can endow them with desired properties for potential applications in the intracellular delivery of membrane-impermeable proteins. However, no research is found to focus on this topic until now. Herein, a monocarboxylic acid (MA) and organic base comodulation strategy is developed to synthesize the hierarchically porous UiO-66 nanoparticles. MA of dodecanoic acid is utilized to control the pore size while trimethylamine (TEA) plays a key role in modulating the nucleation of crystallization to regulate the particle size. In comparison with microporous UiO-66, a model protein of cytochrome c (Cyt c) could be efficiently loaded into the mesoporous MOFs (mesoMOFs). The size-dependent cellular uptake is also evaluated, and it is verified that mesoMOFs with particle size of 90 nm could be endocytosed into living cells with highest efficiency. These outstanding merits enable the current mesoMOFs not only to exhibit efficient encapsulation of Cyt c but also facilitate the protein delivery into the cytosol and subsequent endosomal escape. Given the exceptional chemical stability, hierarchically porous structure as well as tunable particle size, the elaborated mesoUiO-66 nanoparticles might offer a promising platform for a variety of biomedical applications.Size-controllable mesoporous Zr-based metal–organic frameworks (MOFs) are successfully achieved using a facile acid/base comodulator strategy. In virtue of their high efficiency of internalization by living cells in concert with their high biocompatibility as well as the exceptional chemical stability, the prepared large-pore MOFs might offer a new platform for the intracellular delivery of membrane-impermeable biomolecules.
      PubDate: 2018-02-14T09:26:31.379571-05:
      DOI: 10.1002/adfm.201707356
       
  • Low-Cost Chitosan-Derived N-Doped Carbons Boost Electrocatalytic Activity
           of Multiwall Carbon Nanotubes
    • Authors: Mo Qiao; Seyyed Shayan Meysami, Guillermo Alvarez Ferrero, Fei Xie, Han Meng, Nicole Grobert, Maria-Magdalena Titirici
      Abstract: An effective strategy is proposed to enhance the oxygen reduction reaction (ORR) performance of multiwall carbon nanotubes (MWCNTs) in both acid and alkaline electrolytes by coating them with a layer of biomass derivative N-doped hydrothermal carbons. The N-doped amorphous carbon coating plays triple roles: it (i) promotes the assembly of MWCNTs into a 3D network therefore improving the mass transfer and thus increasing the catalytic activity; (ii) protects the Fe-containing active sites, present on the surface of the MWCNTs, from H2O2 poisoning; (iii) creates nitrogenated active sites and hence further enhances ORR activity and robustness.A simple and effective strategy is reported to enhance the oxygen reduction reaction (ORR) performance of multiwall carbon nanotubes (MWCNTs). This approach is based on using biomass-derived amorphous carbon to coat CNTs via a hydrothermal process. The approach of manipulating the interface between MWCNTs and the electrolyte is easy to scale up to fit either batch or continuous process.
      PubDate: 2018-02-14T09:25:47.936742-05:
      DOI: 10.1002/adfm.201707284
       
  • 2D Nanomaterial Arrays for Electronics and Optoelectronics
    • Authors: Chuanhui Gong; Kai Hu, Xuepeng Wang, Peihua Wangyang, Chaoyi Yan, Junwei Chu, Min Liao, Liping Dai, Tianyou Zhai, Chao Wang, Liang Li, Jie Xiong
      Abstract: Two-dimensional (2D) materials, benefitting from their unique planar structure and various appealing electronic properties, have attracted much attention for novel electronic and optoelectronic applications. As a basis for practical devices, the study of micro/nano-2D material arrays based on coupling effects and synergistic effects is critical to the functionalization and integration of 2D materials. Moreover, micro/nano-2D material arrays are compatible with traditional complementary metal oxide semiconductor (CMOS) electronics, catering well to high-integration, high-sensitivity, and low-cost sensing and imaging systems. This review presents some recent studies on 2D material arrays in sequence from their novel preparations to high-integration applications as well as explorations on dimension tuning. A first focus is on various typical fabrication methods for 2D material arrays, including photolithography, 2D printing, seeded growth, van der Waals epitaxial growth, and self-assembly. Then, the applications of 2D material arrays, such as field effect transistors, photodetectors, pressure sensors, as well as flexible electronic devices of photodetectors and strain sensors, are elaborately introduced. Furthermore, the recent burgeoning exploration of mixed-dimensional heterostructure arrays including 0D/2D, 1D/2D, and 3D/2D is discussed. Ultimately, conclusions and an outlook based on the current developments in this promising field are presented.Novel fabrication methods have caused a boom in 2D nanomaterials array development toward high-performance and low-cost microelectronic systems compatible with complementary metal oxide semiconductor electronics. The device prototypes achieved include field-effect transistors, photodetectors, and press sensors. Explorations based on mixed-dimensional heterostructure (0D/2D, 1D/2D, and 3D/2D) arrays are systematically reviewed, and further expectations of 2D arrays are presented.
      PubDate: 2018-02-14T09:23:15.476702-05:
      DOI: 10.1002/adfm.201706559
       
  • High Performance BiOCl Nanosheets/TiO2 Nanotube Arrays Heterojunction UV
           Photodetector: The Influences of Self-Induced Inner Electric Fields in the
           BiOCl Nanosheets
    • Authors: Weixin Ouyang; Feng Teng, Xiaosheng Fang
      Abstract: BiOCl nanosheets/TiO2 nanotube arrays heterojunction UV photodetector (PD) with high performance is fabricated by a facile anodization process and an impregnation method. The heterojunction at the interface and the internal electric fields in the BiOCl nanosheets faciliate the separation of photogenerated charge carriers and regulate the transportation of the electrons. Compared with the large dark current (≈10−5 A), low on/off ratio (8.5), and slow decay time (>60 s) of the TiO2 PD, the optimized heterojunction PD (6-BiOCl–TiO2) yields dramatically decreased dark current (≈1 nA), ultrahigh on/off ratio (up to 2.2 × 105), and fast decay speed (0.81 s) under 350 nm light illumination at −5 V. Moreover, it exhibits an increased responsivity of 41.94 A W−1, a remarkable detectivity (D*) of 1.41 × 1014 Jones, and a high linear dynamic range of 103.59 dB. The loading amount and growth orientations of the BiOCl nanosheets alter the roles of the self-induced internal electric field in regulating the behaviors of the charge carriers, thus affecting the photoelectric properties of the heterojunction PDs. These results demonstrate that rational construction of novel heterojunctions hold great potentials for fabricating photodetectors with high performance.A BiOCl–TiO2 heterojunction UV photodetector with high performance is fabricated. Heterojunctions formed between BiOCl nanosheets and TiO2 nanotube arrays improve the UV photoresponses and response speed of TiO2 film photodetectors. The loading amount and growth orientation of BiOCl nanosheets on the TiO2 film have great influences on the photoelectric performance of the heterojunction photodetector.
      PubDate: 2018-02-14T09:15:56.269399-05:
      DOI: 10.1002/adfm.201707178
       
  • Photoinduced Proton Transfer between Photoacid and pH-Sensitive Dyes:
           Influence Factors and Application for Visible-Light-Responsive Rewritable
           Paper
    • Authors: Ting Zhang; Lan Sheng, Junning Liu, Le Ju, Jianhua Li, Zhen Du, Weiran Zhang, Minjie Li, Sean Xiao-An Zhang
      Abstract: Ink-free printing based on rewritable paper is an efficient and environmental friendly way to reuse paper, protect resources, and save energy for sustainable development of human society. Among various kinds of rewritable media, light responsive rewritable paper (LRP) is one of the most popular research areas due to its clean and favorable noncontact writing. Visible light is more suitable for LRP for its superior penetration and much less damages to organic molecules than UV light. However, visible-light-responsive rewritable paper (VLRP) has only limited successes so far. Herein, a VLRP is newly designed and fabricated based on photoinduced proton transfer (PPT) between photoacid and pH-sensitive dyes. Success of it is highly benefited from systematical investigation and in-depth understanding on the key influence factors, such as concentration-induced undesired isomerization, temperature, humidity, and light intensity, on the PPT and its inverse process. As-prepared VLRP shows long-awaited properties, such as, high color contrast and resolution, appropriate legible time of prints, excellent reversibility (>100 cycles), easiness to achieve multicolor prints, and agreeing well with environmental concept of green printing. In addition, study of influence factors on PPT in this work, to some extent, may also help people understand complex photocycle process in biosystem.A new kind of visible-light-responsive rewritable paper (VLRP) is designed and fabricated based on bioinspired photocycle from photoinduced proton transfer (PPT) between a photoacid and a proton receptor dye. Systematical investigation and in-depth understanding key influence factors on the PPT and its inverse process endow the VLRP with excellent performances.
      PubDate: 2018-02-14T09:11:43.129808-05:
      DOI: 10.1002/adfm.201705532
       
  • Self-Assembled Quasi-3D Nanocomposite: A Novel p-Type Hole Transport Layer
           for High Performance Inverted Organic Solar Cells
    • Authors: Jiaqi Cheng; Hong Zhang, Yong Zhao, Jian Mao, Can Li, Shaoqing Zhang, Kam Sing Wong, Jianhui Hou, Wallace C. H. Choy
      Abstract: Hole transport layer (HTL) plays a critical role for achieving high performance solution-processed optoelectronics including organic electronics. For organic solar cells (OSCs), the inverted structure has been widely adopted to achieve prolonged stability. However, there are limited studies of p-type effective HTL on top of the organic active layer (hereafter named as top HTL) for inverted OSCs. Currently, p-type top HTLs are mainly 2D materials, which have an intrinsic vertical conduction limitation and are too thin to function as practical HTL for large area optoelectronic applications. In the present study, a novel self-assembled quasi-3D nanocomposite is demonstrated as a p-type top HTL. Remarkably, the novel HTL achieves ≈15 times enhanced conductivity and ≈16 times extended thickness compared to the 2D counterpart. By applying this novel HTL in inverted OSCs covering fullerene and non-fullerene systems, device performance is significantly improved. The champion power conversion efficiency reaches 12.13%, which is the highest reported performance of solution processed HTL based inverted OSCs. Furthermore, the stability of OSCs is dramatically enhanced compared with conventional devices. The work contributes to not only evolving the highly stable and large scale OSCs for practical applications but also diversifying the strategies to improve device performance.A novel self-assembled quasi-3D nanocomposite is demonstrated to be an effective top hole transport layer (HTL) for both fullerene and non-fullerene inverted organic solar cells. Due to the better conductivity of this nanocomposite HTL, the thickness sensitivity issue of graphene oxide is addressed. Surface recombination is suppressed and the highest power conversion efficiency can reach 12.13%.
      PubDate: 2018-02-14T09:11:03.838962-05:
      DOI: 10.1002/adfm.201706403
       
  • In Situ Growth of 2D Perovskite Capping Layer for Stable and Efficient
           Perovskite Solar Cells
    • Authors: Peng Chen; Yang Bai, Songcan Wang, Miaoqiang Lyu, Jung-Ho Yun, Lianzhou Wang
      Abstract: 2D halide perovskites have recently been recognized as a promising avenue in perovskite solar cells (PSCs) in terms of encouraging stability and defect passivation effect. However, the efficiency (less than 15%) of ultrastable 2D Ruddlesden–Popper PSCs still lag far behind their traditional 3D perovskite counterparts. Here, a rationally designed 2D-3D perovskite stacking-layered architecture by in situ growing 2D PEA2PbI4 capping layers on top of 3D perovskite film, which drastically improves the stability of PSCs without compromising their high performance, is reported. Such a 2D perovskite capping layer induces larger Fermi-level splitting in the 2D-3D perovskite film under light illumination, resulting in an enhanced open-circuit voltage (Voc) and thus a higher efficiency of 18.51% in the 2D-3D PSCs. Time-resolved photoluminescence decay measurements indicate the facilitated hole extraction in the 2D-3D stacking-layered perovskite films, which is ascribed to the optimized energy band alignment and reduced nonradiative recombination at the subgap states. Benefiting from the high moisture resistivity as well as suppressed ion migration of the 2D perovskite, the 2D-3D PSCs show significantly improved long-term stability, retaining nearly 90% of the initial power conversion efficiency after 1000 h exposure in the ambient conditions with a high relative humidity level of 60 ± 10%.2D perovskite capping layers are grown in situ on top of the 3D perovskite film, leading to an enhanced efficiency of 18.5% in the stacking-layered 2D-3D perovskite solar cells (PSCs). Moreover, the unencapsulated 2D-3D PSCs show drastically improved long-term stability, retaining nearly 90% of the original efficiency after 1000 h exposure in a highly humid environment.
      PubDate: 2018-02-13T07:25:47.146828-05:
      DOI: 10.1002/adfm.201706923
       
  • Room-Temperature Electrochemical Conversion of Metal–Organic Frameworks
           into Porous Amorphous Metal Sulfides with Tailored Composition and
           Hydrogen Evolution Activity
    • Authors: Wenhui He; Raya Ifraemov, Arik Raslin, Idan Hod
      Abstract: The conversion of metal–organic frameworks (MOFs) into inorganic nanomaterials is considered as an attractive means to produce highly efficient electrocatalysts for alternative-energy related applications. Yet, traditionally employed MOF-conversion conditions (e.g., pyrolysis) commonly involve multiple complex high-temperature reaction processes, which often make it challenging to control the composition, pore structure, and active-sites of the MOF-derived catalysts. Herein, a general, simple, room-temperature method is presented for a controlled electrochemical conversion of MOF (EC-MOF) films into porous, amorphous metal sulfides (a-MSx). Detailed X-ray photoelectron spectroscopy analysis and control over independent EC-MOF parameters (e.g., scan-rate and potential window) enable to gain insights on the MOF-conversion mechanisms, and in turn to fine-tune the porosity and composition of the obtained MSx. As a result, a highly active amorphous cobalt sulfide (a-CoSx) electrocatalyst can be designed for hydrogen evolution reaction in neutral pH. Furthermore, the adjustable nature of the EC-MOF method allows to draw conclusions about the correlation between the concentration of catalytically active species (S22− sites) and the hydrogen evolution properties of the a-CoSx. Given the method's generality and the diversity of available MOF structures, EC-MOF provides a compelling platform for a rational design of a wide variety of active electrocatalytic materials.Electrochemical conversion of metal–organic framework (EC-MOF) films is introduced as a versatile tool for constructing active H2-evolution metal sulfide electrocatalysts. EC-MOF enables fine-tuning of the metal sulfide's chemical structure and composition. Thus, given the large variety of available MOFs, the EC-MOF method provides a powerful platform for designing a wide variety of active electrocatalytic materials.
      PubDate: 2018-02-12T04:52:05.498162-05:
      DOI: 10.1002/adfm.201707244
       
  • Low-Voltage, Optoelectronic CH3NH3PbI3−xClx Memory with Integrated
           Sensing and Logic Operations
    • Authors: Feichi Zhou; Yanghui Liu, Xinpeng Shen, Mengye Wang, Fang Yuan, Yang Chai
      Abstract: Nonvolatile optoelectronic memories integrated with the functions of sensing, data storage, and data processing are promising for the potential Internet of things (IoT) applications. To meet the requirements of IoT devices, multifunctional memory devices with low power consumption and secure data storage are highly desirable. This study demonstrates an optoelectronic resistive switching memory integrated with sensing and logic operations by adopting organic–inorganic hybrid CH3NH3PbI3−xClx perovskites, which possess unusual defect physics and excellent light absorption. The CH3NH3PbI3−xClx cell exhibits low operation voltage of 0.1 V with the assistance of light illumination, long-term retention property, and multiple resistance states. Its unique optoelectronic characteristics enable to perform logic operation for inputting one electrical pulse and one optical signal, and detect the coincidence of electrical and optical signal as well. This design provides possibilities for smart sensor in IoT application.Optoelectronic CH3NH3PbI3−xClx perovskite resistive switching memory is designed and fabricated. The memory cell exhibits a low operation voltage of 0.1 V with the assistance of light illumination, long-term retention, and light sensing properties, and can perform logic operations by inputting electrical and optical signals. This device provides possibilities for reducing the complexity in smart sensor design for Internet of things applications.
      PubDate: 2018-02-12T02:16:42.687613-05:
      DOI: 10.1002/adfm.201800080
       
  • DNA Origami-Guided Assembly of the Roundest 60–100 nm Gold Nanospheres
           into Plasmonic Metamolecules
    • Authors: Jaewon Lee; Ji-Hyeok Huh, Kwangjin Kim, Seungwoo Lee
      Abstract: DNA origami can provide programmed information to guide the self-assembly of gold nanospheres (Au NSs) into higher-order supracolloids. Molecularly precise and truly 2D/3D integration of Au NSs is possible using DNA origami-enabled assembly, and the resulting assemblies have potential applications in plasmonics and metamaterials. However, the relatively small size (
      PubDate: 2018-02-12T02:16:28.746041-05:
      DOI: 10.1002/adfm.201707309
       
  • All-Inorganic CsPbI3 Perovskite Phase-Stabilized by Poly(ethylene oxide)
           for Red-Light-Emitting Diodes
    • Authors: Beomjin Jeong; Hyowon Han, Yung Ji Choi, Sung Hwan Cho, Eui Hyuk Kim, Seung Won Lee, Jong Sung Kim, Chanho Park, Dongho Kim, Cheolmin Park
      Abstract: Despite the excellent photoelectronic properties of the all-inorganic cesium lead iodide (CsPbI3) perovskite, which does not contain volatile and hygroscopic organic components, only a few CsPbI3 devices are developed mainly owing to the frequent formation of an undesirable yellow δ-phase at room temperature. Herein, it is demonstrated that a small quantity of poly(ethylene oxide) (PEO) added to the precursor solution effectively inhibits the formation of the yellow δ-phase during film preparation, and promotes the development of a black α-phase at a low crystallization temperature. A systematic study reveals that a thin, dense, pinhole-free CsPbI3 film is produced in the α-phase and is stabilized with PEO that effectively reduces the grain size during crystallization. A thin α-phase CsPbI3 film with excellent photoluminescence is successfully employed in a light-emitting diode with an inverted configuration of glass substrate/indium tin oxide/zinc oxide/poly(ethyleneimine)/α-CsPbI3/poly(4-butylphenyl-diphenyl-amine)/WO3/Al, yielding the characteristic red emission of the perovskite film at 695 nm with brightness, external quantum efficiency, and emission band width of ≈101 cd m−2, 1.12%, and 32 nm, respectively.A small quantity of a poly(ethylene oxide) added in the precursor solution is beneficial for the development of all-inorganic CsPbI3 perovskite in black α-phase with significantly improved ambient stability. Dense, uniform, and pinhole-free CsPbI3 thin films consisting of tens of nanometers black α-phase crystals are successfully fabricated with excellent photophysical properties, leading to high performance light-emitting diodes.
      PubDate: 2018-02-12T02:14:34.832041-05:
      DOI: 10.1002/adfm.201706401
       
  • Kinetics of Space Charge Storage in Composites
    • Authors: Chia-Chin Chen; Edvinas Navickas, Jürgen Fleig, Joachim Maier
      Abstract: Composites of ion and electron conducting phases allow for interfacial storage of a neutral component via space charge effects. The present contribution considers the rate of transport-controlled incorporation and excorporation in such artificial mixed conductors. The upper limit of the relaxation time is determined by interfacial job-sharing diffusion which is analyzed in greater detail. In general cases bulk phases assist by migration processes (dual phase transport). For more complex morphological situations, the considerations are complemented by numerical calculations. Thus the treatment also offers a pertinent approach with respect to the kinetics of solid state supercapacitors. Selected experimental results are included in the discussion.Mass storage at contacts of ionic and electronic conductors enables decoupling of the roles of ions and electrons. A treatment of the kinetics is presented covering diffusion along and transport to the active interfaces. Finite element calculations help understand the situation in complex microstructures. The contribution thus also offers a pertinent account of the kinetics of solid-state supercapacitors.
      PubDate: 2018-02-09T05:15:51.725704-05:
      DOI: 10.1002/adfm.201705999
       
  • Advances in Manganese-Based Oxides Cathodic Electrocatalysts for
           Li–Air Batteries
    • Authors: Bao Liu; Yinglun Sun, Li Liu, Shan Xu, Xingbin Yan
      Abstract: Li–air batteries, characteristic of superhigh theoretical specific energy density, cost-efficiency, and environment-friendly merits, have aroused ever-increasing attention. Nevertheless, relatively low Coulomb efficiency, severe potential hysteresis, and poor rate capability, which mainly result from sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) kinetics, as well as pitiful cycle stability caused by parasitic reactions, extremely limit their practical applications. Manganese (Mn)-based oxides and their composites can exhibit high ORR and OER activities, reduce charge/discharge overpotential, and improve the cycling stability when used as cathodic catalyst materials. Herein, energy storage mechanisms for Li–air batteries are summarized, followed by a systematic overview of the progress of manganese-based oxides (MnO2 with different crystal structures, MnO, MnOOH, Mn2O3, Mn3O4, MnOx, perovskite-type and spinel-type manganese oxides, etc.) cathodic materials for Li–air batteries in the recent years. The focus lies on the effects of crystal structure, design strategy, chemical composition, and microscopic physical parameters on ORR and OER activities of various Mn-based oxides, and even the overall performance of Li–air batteries. Finally, a prospect of the research for Mn-based oxides cathodic catalysts in the future is made, and some new insights for more reasonable design of Mn-based oxides electrocatalysts with higher catalytic efficiency are provided.Manganese-based oxides have been proven to be effective electrocatalysts for Li–O2 electrochemistry. Here, recent research progress about Mn-based oxides with various crystal structures and their composites for Li–air batteries is reviewed; the aim is to provide some constructive guidance to design more effective Mn-based oxides electrocatalysts in this field.
      PubDate: 2018-02-09T01:47:33.320448-05:
      DOI: 10.1002/adfm.201704973
       
  • Tailoring the Surface Chemical Reactivity of Transition-Metal
           Dichalcogenide PtTe2 Crystals
    • Authors: Antonio Politano; Gennaro Chiarello, Chia-Nung Kuo, Chin Shan Lue, Raju Edla, Piero Torelli, Vittorio Pellegrini, Danil W. Boukhvalov
      Abstract: PtTe2 is a novel transition-metal dichalcogenide hosting type-II Dirac fermions that displays application capabilities in optoelectronics and hydrogen evolution reaction. Here it is shown, by combining surface science experiments and density functional theory, that the pristine surface of PtTe2 is chemically inert toward the most common ambient gases (oxygen and water) and even in air. It is demonstrated that the creation of Te vacancies leads to the appearance of tellurium-oxide phases upon exposing defected PtTe2 surfaces to oxygen or ambient atmosphere, which is detrimental for the ambient stability of uncapped PtTe2-based devices. On the contrary, in PtTe2 surfaces modified by the joint presence of Te vacancies and substitutional carbon atoms, the stable adsorption of hydroxyl groups is observed, an essential step for water splitting and the water–gas shift reaction. These results thus pave the way toward the exploitation of this class of Dirac materials in catalysis.Herein, it is demonstrated how the inert surface of PtTe2 can be transformed into a catalyst by implanting Te vacancies and by surface functionalization with substitutional carbon atoms. The stable adsorption of hydroxyl groups represents an essential step for water splitting and the water–gas shift reaction. These results pave the way toward the exploitation of Dirac materials in catalysis.
      PubDate: 2018-02-09T01:44:00.055334-05:
      DOI: 10.1002/adfm.201706504
       
  • Synergistic Effect of Graphene Oxide for Impeding the Dendritic Plating of
           Li
    • Authors: Tara Foroozan; Fernando A. Soto, Vitaliy Yurkiv, Soroosh Sharifi-Asl, Ramasubramonian Deivanayagam, Zhennan Huang, Ramin Rojaee, Farzad Mashayek, Perla B. Balbuena, Reza Shahbazian-Yassar
      Abstract: Dendritic growth of lithium (Li) has severely impeded the practical application of Li-metal batteries. Herein, a 3D conformal graphene oxide nanosheet (GOn) coating, confined into the woven structure of a glass fiber separator, is reported, which permits facile transport of Li-ions thought its structure, meanwhile regulating the Li deposition. Electrochemical measurements illustrate a remarkably enhanced cycle life and stability of the Li-metal anode, which is explained by various microscopy and modeling results. Utilizing scanning electron microscopy, focused ion beam, and optical imaging, the formation of an uniform Li film on the electrode surface in the case of GO-modified samples is revealed. Ab initio molecular dynamics (AIMD) simulations suggest that Li-ions initially get adsorbed to the lithiophilic GOn and then diffuse through defect sites. This delayed Li transfer eliminates the “tip effect” leading to a more homogeneous Li nucleation. Meanwhile, CC bonds rupture observed in the GO during AIMD simulations creates more pathways for faster Li-ions transport. In addition, phase-field modeling demonstrates that mechanically rigid GOn coating with proper defect size (smaller than 25 nm) can physically block the anisotropic growth of Li. This new understanding is a significant step toward the employment of 2D materials for regulating the Li deposition.A three-dimensional conformal graphene oxide coating is reported, which permits regulated transport of lithium ions through its structure while suppressing the dendritic deposition of lithium. The electrochemical measurements illustrate a remarkably enhanced stability of the Li-metal anode, which is explained by various microscopy (optical, scanning electron microscopy/focused ion beam) and modeling (ab initio molecular dynamics and phase-field modeling) results.
      PubDate: 2018-02-07T01:38:05.151533-05:
      DOI: 10.1002/adfm.201705917
       
  • Synergistically Enhanced Oxygen Reduction Electrocatalysis by Subsurface
           Atoms in Ternary PdCuNi Alloy Catalysts
    • Authors: Huawei Wang; Wenjia Luo, Lujun Zhu, Zipeng Zhao, Bin E, Wenzhe Tu, Xiaoxing Ke, Manling Sui, Changfeng Chen, Qi Chen, Yujing Li, Yu Huang
      Abstract: For Pd-based alloy catalysts, the selection of metallic alloying elements and the construction of composition-gradient surface and subsurface layers are critical in achieving superior electrocatalytic activities in, e.g., the oxygen reduction reaction (ORR). Based on the Pd-containing alloy, highly monodispersed PdCuNi ternary alloy nanocrystals are prepared through a wet-chemical approach, and a solution-based oxidative surface treatment protocol is utilized to activate the surface of the nanocrystals. A drastically enhanced ORR activity can be achieved by removing the surface Ni and Cu atoms through the surface treatment protocol. The treated catalyst demonstrates a mass activity of 0.45 A mgPd−1 in alkaline medium, 5 and 2.4 times those of commercial Pt/C and Pd/C, respectively. The first-principle calculation result suggests the critical roles of the coexistence of Ni and Cu atoms and their synergistic interaction beneath the outmost pure Pd layer in optimizing the oxygen binding energy for ORR. The calculation also suggests that the optimal binding energy of oxygen requires an appropriate Ni/Cu ratio in the subsurface layer. This work demonstrates a class of high-performance Pt-free ternary alloy ORR catalysts and may provide a general guideline for the structural design of Pd-based ternary alloy catalysts.A composition-gradient surface-treatment strategy is developed for the PdCuNi ternary alloy electrocatalyst toward the oxygen reduction reaction. Theoretical calculation reveals that the enhancement originates from the synergistic interaction between Cu and Ni atoms in the subsurface layer with appropriate ratios.
      PubDate: 2018-02-07T01:37:17.951757-05:
      DOI: 10.1002/adfm.201707219
       
  • Organic Salt Semiconductor with High Photoconductivity and Long Carrier
           Lifetime
    • Authors: Lei Wang; Sandra Jenatsch, Beat Ruhstaller, Christian Hinderling, Donatas Gesevičius, Roland Hany, Frank Nüesch
      Abstract: Intrinsic photogeneration of charge carriers in organic semiconductors is generally attributed to high energy ionization or exciton dissociation by a strong electric field. Here, high bulk photoconductivity is reported in pristine pentamethine cyanine films with photocurrent onset at the band-edge of the organic semiconductor. Single-layer cyanine diodes with selective hole and electron contacts show linear dependence of photocurrent with reverse voltage and light intensity. Numerical drift-diffusion simulations reveal that the linear resistor behavior stems from low and unbalanced carrier mobilities giving rise to negative space charge. Slow bimolecular recombination kinetics of photoinduced charges obtained by time delayed charge extraction measurements show strongly reduced Langevin recombination with long carrier lifetime of the order of a millisecond. Such reduced charge carrier recombination puts forward a materials concept to be exploited in photodiodes and more generally in optoelectronic devices.High photocurrent generation efficiency in the bulk of a pristine organic salt semiconductor in the absence of electric field and donor–acceptor heterointerface is reported. The long carrier lifetime puts forward a materials concept with reduced charge carrier recombination to be exploited in photodiodes and more generally in optoelectronic devices.
      PubDate: 2018-02-07T01:30:35.030512-05:
      DOI: 10.1002/adfm.201705724
       
  • Hydrocarbons-Driven Crystallization of Polymer Semiconductors for
           Low-Temperature Fabrication of High-Performance Organic Field-Effect
           Transistors
    • Authors: Yanlian Lei; Ping Deng, Qiaoming Zhang, Zuhong Xiong, Qinghua Li, Jiangquan Mai, Xinhui Lu, Xunjin Zhu, Beng S. Ong
      Abstract: While many high-performance polymer semiconductors are reported for organic field-effect transistors (OFETs), most require a high-temperature postdeposition annealing of channel semiconductors to achieve high performance. This negates the fundamental attribute of OFETs being a low-cost alternative to conventional high-cost silicon technologies. A facile solution process is developed through which high-performance OFETs can be fabricated without thermal annealing. The process involves incorporation of an incompatible hydrocarbon binder or wax into the channel semiconductor composition to drive rapid phase separation and instantaneous crystallization of polymer semiconductor at room temperature. The resulting composite channel semiconductor film manifests a nano/microporous surface morphology with a continuous semiconductor nanowire network. OFET mobility of up to about 5 cm2 V−1 s−1 and on/off ratio ≥ 106 are attained. These are hitherto benchmark performance characteristics for room-temperature, solution-processed polymer OFETs, which are functionally useful for many impactful applications.Incorporation of a hydrocarbon binder into a polar donor-acceptor semiconductor enables room-temperature fabrication of a highly ordered channel semiconductor for organic field-effect transistors (OFETs) under ambient conditions. The resulting OFETs have afforded excellent field-effect mobility to about 5 cm2 V−1 s−1 – a benchmark performance for polymer OFETs without postdeposition thermal annealing.
      PubDate: 2018-02-06T12:48:49.766841-05:
      DOI: 10.1002/adfm.201706372
       
  • Mechanically Robust, Highly Ionic Conductive Gels Based on Random
           Copolymers for Bending Durable Electrochemical Devices
    • Authors: Dong Gyu Seo; Hong Chul Moon
      Abstract: Mechanically robust, highly ionic conductive gels based on a random copolymer of poly[styrene-ran-1-(4-vinylbenzyl)-3-methylimidazolium hexafluorophosphate] (P[S-r-VBMI][PF6]) and the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) are successfully prepared. The gels with either homo P[VBMI][PF6] or conventional PS-block-poly(methyl methacrylate)-block-PS (SMS) show significant trade-off between ionic conductivity and mechanical resilience. In contrast, the P[S-r-VBMI][PF6]-based gels exhibit both large elastic modulus (≈0.105 MPa) and ionic conductivity (≈1.15 mS cm−1) at room temperature. To demonstrate that these materials can be used as solid-state electrolytes, the ion gels are functionalized by incorporating electrochromic (EC) chromophores (ethyl viologen, EV2+) and are applied to EC devices (ECDs). The devices show low-voltage operation, large optical transmittance variation, and good cyclic coloration/bleaching stability. In addition, flexible ECDs are fabricated to take advantage of the mechanical properties of the gels. The ECDs have excellent bending durability under both compressive and tensile strains. The versatile P[S-r-VBMI][PF6]-based gel is anticipated to be of advantage in flexible electrochemical applications, such as batteries and electrochemical displays.Mechanically robust, highly conductive ion gels are obtained based on newly designed random copolymers and room-temperature ionic liquids. The versatile ion gels are functionalized to include electrochromism and applied to electrochromic (EC) devices. By taking advantage of the good mechanical resilience of the gel, flexible electrochromic devices are successfully demonstrated exhibiting high bending durability under both tensile and compressive strains.
      PubDate: 2018-02-06T12:46:45.683786-05:
      DOI: 10.1002/adfm.201706948
       
  • Versatile, High-Power, Flexible, Stretchable Carbon Nanotube Sheet Heating
           Elements Tolerant to Mechanical Damage and Severe Deformation
    • Authors: Yourack Lee; Viet Thong Le, Jeong-Gyun Kim, Haeyong Kang, Eun Sung Kim, Seung-Eon Ahn, Dongseok Suh
      Abstract: A macroscopic carbon nanotube (CNT) sheet-based heating element having flexible, stretchable, and damage-tolerant features, and wide applicability in harsh environments, is introduced. Because of the intrinsic connection of extremely flexible CNT bundles throughout the sample by van der Waals interactions without use of a binder, the electrical resistance variation of the CNT sheet on elastomer heating element as a function of strain is completely suppressed to some extent, even when stretched under up to 400% strain, which guarantees electrical stability under severe mechanical deformation. In addition, the spatial uniformity of the heat generated from the microaligned CNT bundles reduces the temperature variation inside the sample, which also guarantees thermal stability and operation at a higher average temperature. Such exceptional performance is achieved by the passivation of the elastomer layer on the CNT sheets. Furthermore, the mechanical robustness of this flexible, stretchable heating element is demonstrated by stable heater operation, even when the heating element is damaged. In addition, this design concept of CNT sheet on elastomer is extended to transparent flexible heaters and electric-thermochromic windows.A deformable, stretchable electric heating element is presented. The synergistic combination of aligned carbon nanotube sheets and highly stretchable elastomer results in outstanding flexible heater performance with superior electrical, thermal, and mechanical properties. A carbon nanotube-based array of nanofibrillar heaters on elastomer guarantees spatial uniformity, as well as damage-tolerant mechanical robustness.
      PubDate: 2018-01-18T05:26:44.413395-05:
      DOI: 10.1002/adfm.201706007
       
  • Molecular Consideration for Small Molecular Acceptors Based on Ladder-Type
           Dipyran: Influences of O-Functionalization and π-Bridges
    • Authors: Lisi Yang; Miao Li, Jinsheng Song, Yuanyuan Zhou, Zhishan Bo, Hua Wang
      Abstract: Molecular engineering of nonfullerene acceptors (NFAs) plays a vital role in the development of organic photovoltaics. Oxygen as an electron donating atom is incorporated into the NFA system as alkoxyl forms at central, terminal, or central conjugated moieties due to the tunability at structural conformation, solubility, electron donating ability, absorption, energy levels, etc. In this work, a novel dipyran-based ladder-type building block (Ph-DTDP), which possesses two oxygen atoms in the conjugated skeleton, is designed and facilely synthesized. It is applied as the donor core for the acceptor–donor–acceptor-type NFA design and such functionalized-O efficiently enhances the electron donating ability, lowers the band gap, redshifts and extends the absorption spectra. In addition, the π-bridge effects are considered as well. Photovoltaic performances are systematically investigated and a high power conversion efficiency of 9.21% can be afforded with an energy loss of 0.57 eV. Meanwhile, the morphologies as well as the carrier mobilities of the blend films are studied to assist further understanding of the structure–property relationships. Overall, the study in this work provides a new promising ladder-type dipyran building block and brings in a novel way to use oxygen in NFA molecular structure design.Dipyran-based ladder-type building block (Ph-DTDP), which possesses two oxygen atoms in the conjugated skeleton and four flanking hexylphenyl side chains, is facilely synthesized. The corresponding acceptor–donor–acceptor-type nonfullerene acceptors are prepared and the influences of O-functionalization and π-bridges on energy levels, absorption spectra, crystalinity, morphologies, and photovoltaic performances are systematically studied.
      PubDate: 2018-01-17T02:51:38.870173-05:
      DOI: 10.1002/adfm.201705927
       
  • Energy Landscape of Vertically Anisotropic Polymer Blend Films toward
           Highly Efficient Polymer Light-Emitting Diodes (PLEDs)
    • Authors: Muhammad Umair Hassan; Yee-Chen Liu, Ali K. Yetisen, Haider Butt, Richard Henry Friend
      Abstract: A blend of two hole-dominant polymers is created and used as the light emissive layer in light-emitting diodes to achieve high luminous efficiency up to 22 cd A−1. The polymer blend F81−xSYx is based on poly(9,9-dioctylfluorene) (F8) and poly(para-phenylene vinylene) derivative superyellow (SY). The blend system exhibits a preferential vertical concentration distribution. The resulting energy landscape modifies the overall charge transport behavior of the blend emissive layer. The large difference between the highest unoccupied molecular orbital levels of F8 (5.8 eV) and SY (5.3 eV) introduces hole traps at SY sites within the F8 polymer matrix. This slows down the hole mobility and facilitates a balance between the transport behavior of both the charge carriers. The balance due to such energy landscape facilitates efficient formation of excitons within the emission zone well away from the cathode and minimizes the surface quenching effects. By bringing the light-emission zone in the middle of the F81−xSYx film, the bulk of the film is exploited for the light emission. Due to the charge trapping nature of SY molecules in F8 matrix and pushing the emission zone in the center, the radiative recombination rate also increases, resulting in excellent device performance.Light-emitting polymer films based on the blend of poly(9,9-dioctylfluorene) and poly(para-phenylene vinylene) derivative superyellow exhibit a preferential vertical concentration distribution. A nonuniform energy landscape due to the large difference between the highest occupied molecular levels of both polymers balances the charge transport in the films and leads to achieving highly efficient light-emitting diodes.
      PubDate: 2018-01-17T02:36:05.36504-05:0
      DOI: 10.1002/adfm.201705903
       
  • Robust Fabrication of Nonstick, Noncorrosive, Conductive Graphene-Coated
           Liquid Metal Droplets for Droplet-Based, Floating Electrodes
    • Authors: Yuzhen Chen; Tingjiao Zhou, Yaoyao Li, Lifei Zhu, Stephan Handschuh-Wang, Deyong Zhu, Xiaohu Zhou, Zhou Liu, Tiansheng Gan, Xuechang Zhou
      Abstract: Nontoxic liquid metals (conductive materials in a liquid state at room temperature) are an emerging class of materials for applications ranging from soft electronics and robotics to medical therapy and energy devices. Their sticky and corrosive properties, however, are becoming more of a critical concern for circuits and devices containing other metals as these are easily destroyed or contaminated by the liquid metals. Herein, a feasible method for fabricating highly conductive graphene-coated liquid metal (GLM) droplets is reported and their application as nonstick, noncorrosive, movable, soft contacts for electrical circuits is demonstrated. The as-prepared GLM droplets consist of a liquid-phase soft core of liquid metal and a slippery outer layer of graphene sheets. These structures address the issue of simultaneous control of the wettability and conductivity of a soft electronic contact by combining extraordinary properties, i.e., nonstick, noncorrosive, yet exhibiting high electronic conductivity while in contact with metal substrates, e.g., Au, Cu, Ag, and Ni. As proof-of-concept, the as-prepared GLM droplets are demonstrated as floating electrodes for movable, recyclable electronic soft contacts in electrical circuits.Highly conductive graphene-coated liquid metal (GLM) droplets are fabricated and used as nonstick, noncorrosive, movable, soft electric contacts for droplet-based soft electronics. The GLM droplets consist of a liquid-phase soft core of liquid metal and a slippery outer layer of graphene sheets, which well addresses the issue of simultaneously controlling the wettability and conductivity of liquid metal droplets.
      PubDate: 2018-01-15T05:23:58.838866-05:
      DOI: 10.1002/adfm.201706277
       
  • Sol–Gel Synthesis of Robust Metal–Organic Frameworks for
           Nanoparticle Encapsulation
    • Authors: Joshua P. Mehta; Tian Tian, Zhixin Zeng, Giorgio Divitini, Bethany M. Connolly, Paul A. Midgley, Jin-Chong Tan, David Fairen-Jimenez, Andrew E. H. Wheatley
      Abstract: A new type of composite material involving the in situ immobilization of tin oxide nanoparticles (SnO2-NPs) within a monolithic metal–organic framework (MOF), the zeolitic imidazolate framework (ZIF)-8 is presented. SnO2@monoZIF-8 exploits the mechanical properties, structural resilience, and high density of a monolithic MOF, while leveraging the photocatalytic action of the nanoparticles. The composite displays outstanding photocatalytic properties and represents a critical advance in the field of treating toxic effluents and is a vital validation for commercial application. Crucially, full retention of catalytic activity is observed after ten catalytic cycles.A new type of composite material involving the in situ immobilization of photoactive tin oxide nanoparticles within a monolithic metal–organic framework, monoZIF-8, is presented. SnO2@monoZIF-8 displays outstanding photocatalytic properties with full retention of activity observed after ten catalytic cycles. This achievement represents a critical advance in the field of treating toxic effluents and is a vital validation for commercial applications.
      PubDate: 2018-01-12T03:31:43.351629-05:
      DOI: 10.1002/adfm.201705588
       
  • Vacuum Calcination Induced Conversion of Selenium/Carbon Wires to Tubes
           for High-Performance Sodium–Selenium Batteries
    • Authors: Xuming Yang; Hongkang Wang, Denis Y. W. Yu, Andrey L. Rogach
      Abstract: A vacuum calcination approach is developed to fabricate selenium/carbon composites, which does not require intensive mixing and durable heating such as in commonly used melt-infusion methods of loading selenium into carbon hosts. Starting from carbon-coated selenium wires prepared via a wet-chemical reaction, selenium/carbon tubes are fabricated by a straightforward calcination process. The calcination is conducted in a confined space to reduce the insulating carbon shell under vacuum, and selenium melts but remains a constituting part of the composite. Paired with sodium metal anode, the resultant selenium/carbon tubes deliver a high reversible capacity of 601 and 509 mA h g−1 at 0.2 and 2 C normalized by the mass of selenium, which corresponds to energy and power densities of 860 and 667 Wh kg−1 at 193 and 1770 W kg−1, respectively. Such capacity and rate performance surpasses most typical cathode materials for lithium or sodium (ion) batteries, according to the comparative literature analysis. Moreover, the robust tubular-like hollow structure of the selenium/carbon composites ensures for impressive capacity retention of more than 90% after 1000 cycles at 20 C.Carbon coated selenium wires are converted into selenium/carbon tubes as a result of calcination treatment in a space-confined space under vacuum. When used as cathode materials for sodium–selenium batteries, the obtained composite delivers exceptional cycle stability and rate performance, which are correlated to the tubular structure and supportive carbon frameworks.
      PubDate: 2018-01-10T12:59:43.025689-05:
      DOI: 10.1002/adfm.201706609
       
  • Hollow Spherical Nanoshell Arrays of 2D Layered Semiconductor for
           High-Performance Photodetector Device
    • Authors: Xiaoshuang Chen; Huihui Yang, Guangbo Liu, Feng Gao, Mingjin Dai, Yunxia Hu, Hongyu Chen, Wenwu Cao, PingAn Hu, Wenping Hu
      Abstract: Well-defined hollow spherical nanoshell arrays of 2D transitional metal dichalcogenide (TMDC) nanomaterials for MoSe2 and MoS2 are grown via chemical vapor deposition technique for the first time. The hollow sphere arrays display the uniform dimensions of ≈450 nm with the shell thickness of ≈10 nm. The unique hollow sphere architecture with increased active surface area is forecasted to supply more efficient route to improve light-harvesting efficiency through repeated light reflection and scattering inside the hollow structure without decay of response and recovery speed, because exceptional “SP–SP” junction barriers conducting mechanism can facilitate carriers tunneling and transport during the electron transfer procedure within the present particular structure. The MoSe2 hollow sphere photodetector exhibits an outstanding responsivity (8.9 A W−1), which is tenfold higher than that for MoSe2 compact film (0.9 A W−1), fast response and recovery speed, and good durability under illumination wavelength of 365 nm. Meanwhile, MoSe2 hollow sphere arrays on flexible polyethylene terephthalate substrates reveal excellent bending stability. Therefore, this research indicates that unique hollow sphere architecture of 2D TMDC materials will be an anticipated avenue for efficient photodetector devices with far-ranging capability.The neoteric hollow spherical nanoshell arrays of 2D transitional metal dichalcogenide nanomaterials assembled from MoSe2 substances are successfully obtained by chemical vapor deposition method for the first time. The MoSe2 hollow sphere arrays with the homogeneous diameter of ≈450 nm and the shell thickness of ≈10 nm exhibit excellent photodetector performance and bending stability on SiO2/Si and flexible polyethylene terephthalate substrates.
      PubDate: 2018-01-10T03:26:05.47301-05:0
      DOI: 10.1002/adfm.201705153
       
  • Dopamine: Just the Right Medicine for Membranes
    • Authors: Hao-Cheng Yang; Ruben Z. Waldman, Ming-Bang Wu, Jingwei Hou, Lin Chen, Seth B. Darling, Zhi-Kang Xu
      Abstract: Mussel-inspired chemistry has attracted widespread interest in membrane science and technology. Demonstrating the rapid growth of this field over the past several years, substantial progress has been achieved in both mussel-inspired chemistry and membrane surface engineering based on mussel-inspired coatings. At this stage, it is valuable to summarize the most recent and distinctive developments, as well as to frame the challenges and opportunities remaining in this field. In this review, recent advances in rapid and controllable deposition of mussel-inspired coatings, dopamine-assisted codeposition technology, and photoinitiated grafting directly on mussel-inspired coatings are presented. Some of these technologies have not yet been employed directly in membrane science. Beyond discussing advances in conventional membrane processes, emerging applications of mussel-inspired coatings in membranes are discussed, including as a skin layer in nanofiltration, interlayer in metal-organic framework based membranes, hydrophilic layer in Janus membranes, and protective layer in catalytic membranes. Finally, some critical unsolved challenges are raised in this field and some potential pathways are proposed to address them.Mussel-inspired polydopamine is a rising star in membrane science and technology. The most recent advances in polydopamine deposition are highlighted and summarized, as well as its emerging applications in nanofiltration, metal-organic framework composite membranes, Janus membranes, and photocatalytic membranes.
      PubDate: 2018-01-09T05:22:02.539785-05:
      DOI: 10.1002/adfm.201705327
       
  • Copper Iodide Based Hybrid Phosphors for Energy-Efficient General Lighting
           Technologies
    • Authors: Wei Liu; Yang Fang, Jing Li
      Abstract: Solid-state-lighting (SSL) is a new lighting technology that is rapidly replacing conventional lighting sources because it is much more energy efficient, longer lasting, and contributes significantly to environmental protection. A main branch of SSL technology is light-emitting diodes (LEDs), and white-light LEDs (WLEDs) are in the greatest demand for general lighting and illumination applications. Current WLED devices rely heavily on rare-earth elements (REEs), which will likely suffer from cost and supply risks and environmental consequences in the near future. Crystalline inorganic–organic hybrid materials based on I–VII binary semiconductors represent a promising material class as REE-free phosphor alternatives. This article provides a brief overview of recent advancement on this material family, with a focus on the rational design, energy-efficient and low-cost synthesis, systematic modification, and optimization of their electronic, optical, and thermal properties. A particular emphasis will be made on our own progress over the past several years in developing four classes of CuI(L) structures with substantially improved performance as energy-saving lighting phosphors. General strategies for structural design, synthesis, and property optimization of these materials will also be discussed.Coupled with their rich structural chemistry; versatile coordination mode; strong and systematic property tunability; excellent photoluminescence performance; simple, easily scalable synthesis; and good solution processability, copper-iodide-based crystalline hybrid inorganic–organic materials demonstrate great promise for use as rare-earth-element-free phosphor candidates for energy-efficient general lighting and illumination technologies.
      PubDate: 2018-01-09T05:20:37.217989-05:
      DOI: 10.1002/adfm.201705593
       
  • Rational Synthesis of Large-Area Periodic Chemical Gradients for the
           Manipulation of Liquid Droplets and Gas Bubbles
    • Authors: Karla Perez-Toralla; Abhiteja Konda, John J. Bowen, Emily E. Jennings, Christos Argyropoulos, Stephen A. Morin
      Abstract: Synthetic approaches based on the patterned deposition of volatile molecules from the vapor phase are used extensively in the creation of surface-chemical gradients; however, the ability to generate diffusion-controlled 1D and 2D gradients from multiple sources remains a challenge. The current work reports a one-step approach to the synthesis of continuous and periodic chemical gradients with simple and intricate geometries using multiple sources within custom reaction chambers. Specifically, this approach provides precise, simultaneous control over the physicochemical conditions (e.g., concentration, evaporation rate, and direction of diffusion flux of the chemical moieties) and the geometrical parameters (e.g., size, shape, and position) during surface functionalization, thus enabling materials with predictable surface-chemical gradients applicable to the manipulation and/or organization of liquid droplets and that can generate assemblies of functional solids (e.g., silver nanoparticles) that are transferrable via stamping. These surfaces can be useful to various fields, for example, molecular diagnostics and microfabrication. Furthermore, this work extends the application of these surfaces to the precise placement and manipulation of gas bubbles that can have potential use in, for example, controlling bubble nucleation in processes designed to manage heat transfer.A one-step approach for the synthesis of continuous and periodic chemical gradients with simple, intricate, and predictable (via control of the physiochemical parameters) geometries using multiple sources within custom reaction chambers is described. These chemical gradients are transferable to various planar and non-planar surfaces, and applicable to, for example, the manipulation of liquid droplets and gas bubbles.
      PubDate: 2018-01-09T02:23:58.885604-05:
      DOI: 10.1002/adfm.201705564
       
  • Artificial Soft–Rigid Protective Layer for Dendrite-Free Lithium
           Metal Anode
    • Authors: Rui Xu; Xue-Qiang Zhang, Xin-Bing Cheng, Hong-Jie Peng, Chen-Zi Zhao, Chong Yan, Jia-Qi Huang
      Abstract: Lithium (Li) metal has been pursued as “Holy Grail” among various anode materials due to its high specific capacity and the lowest reduction potential. However, uncontrolled growth of Li dendrites and extremely unstable interfaces during repeated Li plating/stripping ineluctably plague the practical applications of Li metal batteries. Herein, an artificial protective layer with synergistic soft–rigid feature is constructed on the Li metal anode to offer superior interfacial stability during long-term cycles. By suppressing random Li deposition and the formation of isolated Li, such a protective layer enables a dendrite-free morphology of Li metal anode and suppresses the depletion of Li metal and electrolyte. Additionally, sufficient ionic conductivity is guaranteed through the synergy between soft and rigid structural units that are uniformly dispersed in the layer. Dendrite-free and dense Li deposition, as well as a greatly reduced interfacial resistance after cycling, is achieved owing to the stabilized interface, accounting for significantly prolonged cycle life of Li metal batteries. This work highlights the ability of synergistic organic/inorganic protective layer in stabilizing Li metal anode and provides fresh insights into the energy chemistry and mechanics of anode in a working battery.An artificial protective layer based on the manipulation in the mechanical properties of soft–rigid and organic–inorganic hybrids is proposed for safe lithium metal anodes. The soft organic or polymeric materials offer stretchability to tolerate the volume fluctuation, while the rigid inorganic materials provide mechanical reinforcement and suppress the growth of lithium dendrites.
      PubDate: 2018-01-08T03:39:15.937002-05:
      DOI: 10.1002/adfm.201705838
       
  • Multifaceted Implantable Anticancer Device for Potential Postsurgical
           Breast Cancer Treatment: A Single Platform for Synergistic Inhibition of
           Local Regional Breast Cancer Recurrence, Surveillance, and Healthy Breast
           Reconstruction
    • Authors: Arathyram Ramachandra Kurup Sasikala; Afeesh Rajan Unnithan, Reju George Thomas, Sung Won Ko, Yong Yeon Jeong, Chan Hee Park, Cheol Sang Kim
      Abstract: An implantable anticancer device (IAD) amenable to eradicate local regional recurrence (LRR) of breast cancer as well as to enhance the breast reconstruction during/after therapy is proposed for the first time. The IAD is fabricated by incorporating the superparamagnetic graphene oxide doxorubicin nanocomposite of size ≈200 nm in a nanofiber matrix to enable the sustained and tumor specific anticancer drug release over 60 d in vitro with a minimum initial burst release and the repeated hyperthermic capability in an alternating magnetic field to ensure the synergistic inhibition of LRR. The IAD also enriches the reconstruction of poor breast cosmesis that resulted from the surgical treatment by supporting the lipofilling of the surgical residual cavity to induce the adipogenic process. Moreover, the noninvasive monitoring capability of IAD through magnetic resonance imaging augments to the effective patient care. Thus, this work reports a new and reliable concept by introducing the multifunctional IAD possessing enhanced specificity with a real-time monitoring capability and long-term anticancer efficacy as a potential platform for synergistic inhibition of LRR and a great promise for the in situ breast reconstruction ability for better breast cosmesis.An implantable anticancer device (IAD) combining the tetra functionalities for postsurgical breast cancer treatment are proposed. The IAD enables sustained and site specific anticancer drug delivery along with repeated hyperthermic capability and magnetic resonance imaging. The IAD also promotes the adipogenesis of preadipocytes through the typical topographical features of the IAD by avoiding the use of complex cues for differentiation.
      PubDate: 2017-12-20T07:22:18.415955-05:
      DOI: 10.1002/adfm.201704793
       
  • Spin-Controlled Integrated Near- and Far-Field Optical Launcher
    • Authors: Qiao Jiang; Yanjun Bao, Feng Lin, Xing Zhu, Shuang Zhang, Zheyu Fang
      Abstract: With the evergrowing demand for miniaturization of photonic devices, the integration of different functionalities in a single module is highly desired for the next generation of ultracompact photonic devices. Optical modules based on the near field and scattered far field are both key elements in the construction of nanophotonic devices. However, integrating the near- and far-field functionalities into a single module is a great challenge, which hinders the integration and minimization of optical devices. Here, a bifunctional integrated near- and far-field optical launcher with a single metasurface structure is theoretically proposed and experimentally demonstrated, where the unidirectional launching of surface plasmon polaritons (SPPs) and the focusing of scattered far fields can be simultaneously achieved. Moreover, the SPP propagating direction and the real/virtual focus of the far-field scattering can be actively controlled by the spin state of the incident light. With the additional degree of freedom provided by the positions of the metasurface elements, the optical performances of this bifunctional structure can be compared to the one with single functionality. The work provides a new platform for the integration and control of different optical components at subwavelength scale, and opens a way to design multifunctional optical devices for the future.A single metasurface that can act as a bifunctional optical modulator with its geometric phase tailored in both near and far field is designed and demonstrated. It enables unidirectional launching of surface plasmon polaritons and focusing of far-field light simultaneously. The near-field propagation direction and the far-field focusing polarity can be further actively controlled by the spin of incident light.
      PubDate: 2017-12-20T07:16:14.384614-05:
      DOI: 10.1002/adfm.201705503
       
  • Anatase (101) Reconstructed Surface with Novel Functionalities: Desired
           Bandgap for Visible Light Absorption and High Chemical Reactivity
    • Authors: Rulong Zhou; Bingyan Qu, Dongdong Li, Xiaorui Sun, Xiao Cheng Zeng
      Abstract: Unreconstructed surfaces of anatase TiO2 are known to have two main limitations for their application as photocatalysts, namely, low efficiency for sun-light absorption due to the wide bandgap, and low chemical reactivity. Strategies to overcoming the two limitations and to enhancing TiO2's photocatalytic efficiency have been highly sought. To this end, a global search of anatase reconstructed surfaces is performed based on the evolutionary method. It is found that the newly predicted anatase (101) reconstructed surface possesses a desired bandgap whose value is within the energy domain of visible light as well as notably high chemical reactivity compared to the unreconstructed anatase (101) surface. In particular, it is predicted that under Ti-richness condition, the anatase (101) reconstructed surface is energetically very stable. The anatase (101) reconstructed surface exhibits similar topmost surface structure as the unreconstructed anatase (101) surface but different subsurface structure. Not only the fivefold coordinated Ti atoms (Ti5c) in the topmost surface layer but also the sixfold coordinated Ti atoms in the subsurface layer contribute to the desirable gap states. The high chemical reactivity of anatase (101) reconstructed surface can be attributed to the extra electrons drawn by the surface Ti5c atoms and subsurface Ti6c atoms.A novel anatase TiO2 (101) reconstructed surface is reported theoretically. It possesses a desired bandgap whose value is within the energy domain of visible light as well as notably high chemical reactivity compared to the unreconstructed anatase (101) surface. So, this new surface, if confirmed by future experiments, can offer high opportunity and incentives for the TiO2-based photocatalytic applications.
      PubDate: 2017-12-20T07:15:40.514118-05:
      DOI: 10.1002/adfm.201705529
       
  • Growth and Luminescence of Polytypic InP on Epitaxial Graphene
    • Authors: Samik Mukherjee; Nima Nateghi, Robert M. Jacobberger, Etienne Bouthillier, Maria de la Mata, Jordi Arbiol, Toon Coenen, Dhan Cardinal, Pierre Levesque, Patrick Desjardins, Richard Martel, Micheal S. Arnold, Oussama Moutanabbir
      Abstract: Van der Waals epitaxy is an attractive alternative to direct heteroepitaxy where the forced coherency at the interface cannot sustain large differences in lattice parameters and thermal expansion coefficients between the substrate and the epilayer. Herein, the growth of monocrystalline InP on Ge and SiO2/Si substrates using graphene as an interfacial layer is demonstrated. Micrometer-sized InP crystals are found to grow with interfaces of high crystalline quality and with different degrees of coalescence depending on the growth conditions. Some InP crystals exhibit a polytypic structure, consisting of alternating zinc-blende and wurtzite phases, forming a type-II homojunction with well (barrier) width of about 10 nm. The optical properties, investigated using room temperature nano-cathodoluminescence, indicate the signatures of the direct optical transitions at 1.34 eV across the gap of the zinc-blende phase and the indirect transitions at ≈1.31 eV originating from the alternating zinc-blende and wurtzite phases. Additionally, the InP nanorods, found growing mainly on the graphene/SiO2/Si substrate, show optical transition across the gap of the wurtzite phase at ≈1.42 eV. This demonstration of InP growth on graphene and the correlative study between the structure and optical properties pave the way to develop hybrid structures for potential applications in integrated photonic and optoelectronic devices.The InP–graphene hybrid structures achieved by exploiting quasi van der Waals epitaxy on group IV substrates are illustrated. The room temperature optical emissions the signature transitions across the zinc-blend gap as well as alternating zinc-blende/wurtzite phases, forming a type II homojunction. The development of these hybrid structures lays the groundwork to implement innovative photonic and optoelectronic devices.
      PubDate: 2017-12-20T07:12:10.587044-05:
      DOI: 10.1002/adfm.201705592
       
  • Local Structure and Chemistry of C-Doped ZnO@C Core–Shell Nanostructures
           with Room-Temperature Ferromagnetism
    • Authors: Duc-The Ngo; Le Thanh Cuong, Nguyen Huu Cuong, Cao Thai Son, Pham Thanh Huy, Nguyen Duc Dung
      Abstract: A superior approach is presented to study quantitatively fine structure of C-doped ZnO nanostructure using transmission electron microscopy (TEM) from which the role of carbon in ZnO crystal to form ferromagnetism is revealed at the first time. Electron diffraction in TEM shows Wurtzite structure in the nanoparticles with lattice parameters (a = 0.327 ± 0.03 nm and c = 0.529 ± 0.04 nm) slightly different from the original structure. Interestingly, the Zn–C bonding with a bonding length of 2.58 Å is experimentally determined using atomic pair distribution function (PDF) calculated from electron diffraction data. Together with other bondings, such as C–C, Zn–O obtained from the PDF, this demonstrates migration of C atoms into ZnO crystal to substitute O vacancies. This is furthermore visualized by high-resolution TEM imaging and elemental mapping, and strongly supports the proposal of origin of ferromagnetism in the C-doped ZnO nanoparticles where the s–p and p–p hybridizations formed by C2p–Zn4s, and O2p–C2p orbitals are believed to cause ferromagnetism.The paper presents a superior approach to understand the role of carbon in ZnO to form ferromagnetism. ZnC and CC bonds with the lengths of 2.58 and 1.42 Å, respectively are determined using atomic pair distribution function calculated from electron diffraction in transmission electron microscopy indicating substitution of C for O to form the ferromagnetism via s–p and p–p orbital hybridizations.
      PubDate: 2017-12-19T12:40:43.026264-05:
      DOI: 10.1002/adfm.201704567
       
  • Porphyrinic Metal–Organic Frameworks Coated Gold Nanorods as a Versatile
           
    • Authors: Jin-Yue Zeng; Ming-Kang Zhang, Meng-Yun Peng, Dan Gong, Xian-Zheng Zhang
      Abstract: In this paper, a simple, but effective method is reported to construct the core−shell gold nanorod@metal–organic frameworks (AuNR@MOFs) as a multifunctional theranostic platform by using functionalized AuNRs as seed crystal for the growth of porphyrinic MOFs on the surface of AuNR. Such a delicate tunable core−shell composite not only possesses the improved drug loading efficiency, near-infrared light-trigger drug release, and fluorescence imaging, but also can produce reactive oxygen species as well as photothermal activity to achieve combined cancer therapy. It is further demonstrated that the camptothecin loaded AuNR@MOFs show distinctively synergistic efficiency for damaging the cancer cell in vitro and inhibiting the tumor growth and metastasis in vivo. The development of this high-performance incorporated nanostructure will provide more perspectives in the design of versatile nanomaterials for biomedical applications.Porphyrinic metal–organic frameworks coated gold nanorods (AuNR@MOFs) are reported as a theranostic platform for combined photodynamic/photothermal/chemotherapy of tumor. The delicate core–shell AuNR@MOFs not only possess improved drug loading efficiency, near-infrared light-triggered drug release, and fluorescence imaging, but also are able to produce reactive oxygen species as well as photothermal activity to achieve synergistic tumor therapy.
      PubDate: 2017-12-19T12:37:12.760556-05:
      DOI: 10.1002/adfm.201705451
       
  • Novel Type-II InAs/AlSb Core–Shell Nanowires and Their Enhanced Negative
           Photocurrent for Efficient Photodetection
    • Authors: Handong Li; Hayfaa Alradhi, Zhiming Jin, Ezekiel A. Anyebe, Ana M. Sanchez, Wojcioech M. Linhart, Robert Kudrawiec, Hehai Fang, Zhiming Wang, Weida Hu, Qiandong Zhuang
      Abstract: The control of optical and transport properties of semiconductor heterostructures is crucial for engineering new nanoscale photonic and electrical devices with diverse functions. Core–shell nanowires are evident examples of how tailoring the structure, i.e., the shell layer, plays a key role in the device performance. However, III–V semiconductors bandgap tuning has not yet been fully explored in nanowires. Here, a novel InAs/AlSb core–shell nanowire heterostructure is reported grown by molecular beam epitaxy and its application for room temperature infrared photodetection. The core–shell nanowires are dislocation-free with small chemical intermixing at the interfaces. They also exhibit remarkable radiative emission efficiency, which is attributed to efficient surface passivation and quantum confinement induced by the shell. A high-performance core–shell nanowire phototransistor is also demonstrated with negative photoresponse. In comparison with simple InAs nanowire phototransistor, the core–shell nanowire phototransistor has a dark current two orders of magnitude smaller and a sixfold improvement in photocurrent signal-to-noise ratio. The main factors for the improved photodetector performance are the surface passivation, the oxide in the AlSb shell and the type-II bandgap alignment. The study demonstrates the potential of type-II core–shell nanowires for the next generation of photodetectors on silicon.Novel InAs/AlSb core–shell nanowires are reported grown on silicon by molecular beam epitaxy. The core–shell nanowires are dislocation-free with a type II bandgap alignment. Such core–shell nanowire is featured with efficient passivation and enhanced negative photoresponse consequently holds great promise in infrared photodetection.
      PubDate: 2017-12-19T12:36:18.5413-05:00
      DOI: 10.1002/adfm.201705382
       
  • Optical Data Storage and Multicolor Emission Readout on Flexible Films
           Using Deep-Trap Persistent Luminescence Materials
    • Authors: Yixi Zhuang; Le Wang, Ying Lv, Tian-Liang Zhou, Rong-Jun Xie
      Abstract: The fast-growing amount of data that is produced every year creates an urgent need for ultracapacity storage media. However, 2D spatial resolution in the conventional optical data storage media has almost reached the limit. Further enlargement of storage capacity may rely on the development of the next-generation data storage materials containing multiplexed information dimensions. Herein, a series of novel deep-trap persistent luminescence materials (Sr1-xBax)Si2O2N2:Eu/Yb,Dy with multicolor emissions in the whole visible region is developed and demonstrated a bit-by-bit optical data storage and readout strategy based on photon trapping and detrapping processes in these materials. Optical data can be handily encoded on a flexible film by a commercially available 405 nm laser and decoded by heating or by 980 nm laser scanning. The decoded information contains tunable spectral characteristics, which allows for the emission–intensity–multiplexing or emission–wavelength–multiplexing. The storage and readout strategy not only shows a great promise in the application of multidimensional rewritable optical data storage, but also opens new opportunities for advanced display technology and information security system.A bit-by-bit optical data storage and readout strategy based on photon trapping and detrapping processes in deep-trap persistent luminescence materials is demonstrated in this study. The readout information contains tunable spectral characteristics, allowing for the emission–intensity–multiplexing or emission–wavelength–multiplexing, which may greatly enlarge the storage capacity in multidimensional data storage systems.
      PubDate: 2017-12-19T06:11:53.95376-05:0
      DOI: 10.1002/adfm.201705769
       
  • The Misfit Dislocation Core Phase in Complex Oxide Heteroepitaxy
    • Authors: Núria Bagués; José Santiso, Bryan D. Esser, Robert E. A. Williams, Dave W. McComb, Zorica Konstantinovic, Lluís Balcells, Felip Sandiumenge
      Abstract: Misfit dislocations form self-organized nanoscale linear defects exhibiting their own distinct structural, chemical, and physical properties which, particularly in complex oxides, hold a strong potential for the development of nanodevices. However, the transformation of such defects from passive into potentially active functional elements necessitates a deep understanding of the particular mechanisms governing their formation. Here, different atomic resolution imaging and spectroscopic techniques are combined to determine the complex structure of misfit dislocations in the perovskite type La0.67Sr0.33MnO3/LaAlO3 heteroepitaxial system. It is found that while the position of the film–substrate interface is blurred by cation intermixing, oxygen vacancies selectively accumulate at the tensile region of the dislocation strain field. Such accumulation of vacancies is accompanied by the reduction of manganese cations in the same area, inducing chemical expansion effects, which partly accommodate the dislocation strain. The formation of oxygen vacancies is only partially electrically compensated and results in a positive net charge q ≈ +0.3 ± 0.1 localized in the tensile region of the dislocation, while the compressive region remains neutral. The results highlight a prototypical core model for perovskite-based heteroepitaxial systems and offer insights for predictive manipulation of misfit dislocation properties.Oxygen vacancies tune the interplay between elastic and electrostatic effects at misfit dislocations in La0.67Sr0.33MnO3/LaAlO3. Their selective formation in the tensile zone reduces neighboring Mn cations resulting in a localized net positive charge. The resulting distribution of cationic species on the dislocation strain field is thus governed by electrostatic interactions rather than elastic effects as expected from classical models.
      PubDate: 2017-12-19T06:11:16.607197-05:
      DOI: 10.1002/adfm.201704437
       
  • Versatile Microfluidic Platforms Enabled by Novel Magnetorheological
           Elastomer Microactuators
    • Authors: Shi-Yang Tang; Xuchun Zhang, Shuaishuai Sun, Dan Yuan, Qianbin Zhao, Sheng Yan, Lei Deng, Guolin Yun, Jun Zhang, Shiwu Zhang, Weihua Li
      Abstract: Microfluidic systems enable rapid diagnosis of diseases, biological analysis, drug screening, and high-precision materials synthesis. In spite of these remarkable abilities, conventional microfluidic systems are microfabricated monolithically on a single platform and their operations rely on bulky expensive external equipment. This restricts their applications outside of research laboratories and prevents development and assembly of truly versatile and complex systems. Here, novel magnetorheological elastomer (MRE) microactuators are presented including pumps and mixers using an innovative actuation mechanism without the need of delicate elements such as thin membranes. Modularized elements are realized using such actuators, which can be easily integrated and actuated using a single self-contained driving unit to create a modular, miniaturized, and robust platform. The performance of the microactuators is investigated via a series of experiments and a proof-of-concept modular system is developed to demonstrate the viability of the platform for self-contained applications. The presented MRE microactuators are small size, simple, and efficient, offering a great potential to significantly advance the current research on complex microfluidic systems.Novel magnetorheological elastomer (MRE) microactuators are presented including pumps and mixers using an innovative actuation mechanism. Modularized elements are realized using MRE actuators, which can be easily integrated and actuated using a single self-contained driving unit to create a modular and miniaturized platform. Such a system will offer a great potential to advance the current research on complex microfluidic systems.
      PubDate: 2017-12-19T06:04:14.533617-05:
      DOI: 10.1002/adfm.201705484
       
  • Superelastic and Arbitrary-Shaped Graphene Aerogels with Sacrificial
           Skeleton of Melamine Foam for Varied Applications
    • Authors: Chenwei Li; Degang Jiang, Hui Liang, Bingbing Huo, Chenyang Liu, Wenrong Yang, Jingquan Liu
      Abstract: Elastic graphene aerogels are lightweight and offer excellent and electrical performance, expanding their significance in many applications. Recently, elastic graphene aerogels have been fabricated via various methods. However, for most reported elastic graphene aerogels, the fabrication processes are complicated and the applications are usually limited by the brittle mechanical properties. Thus, it still remains a challenge to explore facile processes for the fabrication of graphene aerogels with low density and high compressibility. Herein, arbitrary-shaped, superelastic, and durable graphene aerogels are fabricated using melamine foam as sacrificial skeleton. The resulting graphene aerogels possess high elasticity under compressive stress of 0.556 MPa and compressive strain of 95%. Thanks to the superelasticity, high strength, excellent flexibility, outstanding thermal stability, and good electrical conductivity of graphene aerogels, they can be applied in sorbents and pressure/strain sensors. The as-assembled graphene aerogels can adsorb various organic solvents at 176–513 g g−1 depending on the solvent type and density. Moreover, both the squeezing and combustion methods can be adopted for reusing the graphene aerogels. Finally, the graphene aerogels exhibit stable and sensitive current responses, making them the ideal candidates for applications as multifunctional pressure/strain sensors such as wearable devices.Superelastic, arbitrary-shaped, and durable graphene aerogels can be fabricated using melamine foam as a sacrificial skeleton. The resulting graphene aerogels exhibit superelasticity, high strength, excellent flexibility, outstanding thermal stability, and good electrical conductivity, making them the ideal candidates for applications as promising sorbents for the removal of pollutants and multifunctional pressure/strain sensors such as wearable devices.
      PubDate: 2017-12-19T06:03:14.216246-05:
      DOI: 10.1002/adfm.201704674
       
  • Facile Synthesis of Blocky SiOx/C with Graphite-Like Structure for
           High-Performance Lithium-Ion Battery Anodes
    • Authors: Quan Xu; Jian-Kun Sun, Ya-Xia Yin, Yu-Guo Guo
      Abstract: SiOx-containing graphite composites have aroused great interests as the most promising alternatives for practical application in high-performance lithium-ion batteries. However, limited loading amount of SiOx on the surface of graphite and some inherent disadvantages of SiOx such as huge volume variation and poor electronic conductivity result in unsatisfactory electrochemical performance. Herein, a novel and facile fabrication approach is developed to synthesize high-performance SiOx/C composites with graphite-like structure in which SiOx particles are dispersed and anchored in the carbon materials by restoring original structure of artificial graphite. The multicomponent carbon materials are favorable for addressing the disadvantages of SiOx-based anodes, especially for the formation of stable solid electrolyte interphase, maintaining structural integrity of electrode materials and improving electrical conductivity of electrode. The resultant SiOx/C anodes demonstrate high reversible capacities (645 mA h g−1), excellent cycling stability (≈90% capacity retention for 500 cycles), and superior rate capabilities. Even at high pressing density (1.3 g cm−3), SiOx/C anodes still present superior cycling performance due to the high tap density and structural integrity of electrode materials. The proposed synthetic method can also be developed to address other anode materials with inferior electronic conductivity and huge volume variation.A blocky SiOx/C with graphite-like structure is optimally designed and synthesized to load more SiOx materials and address the inherent disadvantages of SiOx-based anodes by the synergistic effect of multicomponent carbon materials. The resultant SiOx/C anodes present superior electrochemical performance at high mass loading and pressing density.
      PubDate: 2017-12-19T06:01:09.918987-05:
      DOI: 10.1002/adfm.201705235
       
  • Rational Design of Tumor Microenvironment-Activated Micelles for Programed
           Targeting of Breast Cancer Metastasis
    • Authors: Bin He; Tao Tan, Hong Wang, Haiyan Hu, Zhiwan Wang, Jing Wang, Jie Li, Kaoxiang Sun, Zhiwen Zhang, Yaping Li
      Abstract: The poor drug delivery to primary and metastatic tumors of breast cancer remains a great challenge for effective antimetastasis therapy. Herein, a tumor microenvironment-activated cabazitaxel micelles decorated with legumain-specific melittin (TCM-legM) are rationally designed for programed targeting of breast cancer metastasis. TCM-legM is quiescent in blood circulation, but can be specifically activated by the highly expressed legumain in tumor microenvironments to improve their specific targeting and deep penetrating to primary or metastatic tumors. Thereafter, the activated TCM-legM can be efficiently internalized by cancer cells and motivate the rapid pH-responsive drug release for antimetastasis therapy. In metastatic 4T1 breast cancer cells, TCM-legM presents significant inhibition on the proliferation, migration, and invasion activities. In vivo, TCM-legM can be effectively delivered to both primary and metastatic tumors of breast cancer with deep tumor penetration and efficient cellular internalization, thereby resulting in a notable reduction of tumor growth and producing a 93.4% suppression of lung metastasis. Taken together, the rationally designed TCM-legM can provide an intelligent drug delivery strategy to enhance the medical performance on treating breast cancer metastasis.The poor drug delivery to both primary and metastatic tumors of breast cancer remains a great challenge for antimetastasis therapy. Herein, a tumor microenvironment-activated cabazitaxel micelles decorated with legumain-specific melittin (TCM-legM) are rationally designed that can realize the specific accumulation, deep tumor penetration, efficient cellular uptake, and intelligent pH-sensitive drug release, thereby facilitating the programed targeting of breast cancer metastasis.
      PubDate: 2017-12-19T02:37:13.542375-05:
      DOI: 10.1002/adfm.201705622
       
  • Highly Efficient Rapid Annealing of Thin Polar Polymer Film Ferroelectric
           Devices at Sub-Glass Transition Temperature
    • Authors: Vasileia Georgiou; Dmitry Veksler, Jason T. Ryan, Jason P. Campbell, Pragya R. Shrestha, Dimitris E. Ioannou, Kin P. Cheung
      Abstract: An unexpected rapid anneal of electrically active defects in an ultrathin (15.5 nm) polar polyimide film at and below glass transition temperature (Tg) is reported. The polar polymer is the gate dielectric of a thin-film-transistor. Gate leakage current density (Jg) through the polymer initially increases with temperature, as expected, but decreases rapidly at Tg − 60 °C. After ≈2 min at Tg, the leakage is reduced by nearly three orders of magnitude. A concomitant observation is that the drain current (Id)–gate voltage (Vg) hysteresis decreases with temperature, reaching zero at nearly the same temperature at which Jg collapses. As Jg drops further, the drain current hysteresis increases again but in the opposite direction. This combination strongly supports the interpretation of rapid defect annealing.Defect reduction in a polymer through annealing is a lengthy process at high temperature (melting). This study reports a surprisingly effective defect reduction through a short (≈2 min) annealing at moderate temperature (glass transition). This rapid annealing property is believed to be applicable only to defects created by small atomic displacement, such as elastic stress arising from metal contact deposition.
      PubDate: 2017-12-18T07:39:06.224232-05:
      DOI: 10.1002/adfm.201704165
       
  • Polysulfide Stabilization: A Pivotal Strategy to Achieve High Energy
           Density Li–S Batteries with Long Cycle Life
    • Authors: Yuqing Chen; Hongzhang Zhang, Wenbin Xu, Xiaofei Yang, Ying Yu, Xianfeng Li, Huamin Zhang
      Abstract: The disproportionation of polysulfide (PS) is a long-neglected and vital issue that causes the fast capacity fading of Li–S batteries. Based on the hard and soft acids and bases (HSAB) theory, a large size N-methyl-N-ethyl pyrrolidinium (MEP+) cation is proposed to complex and stabilize the PS in electrolyte. The disproportionation of PS is successfully suppressed by this simple method, thereby avoiding the precipitation of sulfur in the electrolyte and reducing the loss of the active materials. The mutual interaction mechanism between MEP+ and Sn2− in electrolyte is comprehensively investigated and verified for the first time, via both density functional theory (DFT) calculation and experimental characterization. It enables the 5000 mA h Li–S batteries (soft package type) to achieve initial specific energy over 300 Wh kg−1 and maintain over 65% after 100 charge/discharge cycles at 1/20 C, while merely 24% is remained at 59 cycles without MEP+. This interesting finding is believed to shed light on the further development of Li–S batteries.Reduced polysulfide disproportionation and prolonged lifetime of high energy density Li–S batteries are achieved via introducing a large size cation to complex and stabilize the polysulfide in electrolyte, based on the hard and soft acids and bases theory.
      PubDate: 2017-12-18T04:23:33.176503-05:
      DOI: 10.1002/adfm.201704987
       
  • Influence of the Nature of A Cation on Dynamics of Charge Transfer
           Processes in Perovskite Solar Cells
    • Authors: Pankaj Yadav; Mohammad Hayal Alotaibi, Neha Arora, M. Ibrahim Dar, Shaik Mohammed Zakeeruddin, Michael Grätzel
      Abstract: The electronic processes occurring within the perovskite solar cells (PSCs) are strongly influenced by the nature of the organic A cations present within the inorganic framework. In this study, the impact of FA (CH(NH2)2+) and Cs+ cations on the intrinsic and interfacial properties in the FAPbBr3 and CsPbBr3 PSCs is investigated. The analysis of current density (JSC) and photovoltage (VOC) as a function of illumination intensity establishes that the interfacial charge transport is more rapid in FAPbBr3 devices. Small perturbation measurements including intensity modulated photocurrent and photovoltage spectroscopy are applied to explore the resistive and capacitive elements. Furthermore, electrochemical impedance spectroscopy measurements are found to correlate well with the photovoltaic characteristics of FAPbBr3 and CsPbBr3 PSCs. Overall, the in-depth analysis of various phenomena occurring within the bromide PSCs allows to underline the working principle, which provides a key to optimize the device performance. The present protocol is not only valid for PSCs but can also be extended to devices based on alternative light harvesters.The effect of cations on the intrinsic and interfacial dynamic processes occurring in the perovskite solar cells is explored, which allow to underline their working principle.
      PubDate: 2017-12-18T04:22:55.752202-05:
      DOI: 10.1002/adfm.201706073
       
  • Electrode Work Function Engineering with Phosphonic Acid Monolayers and
           Molecular Acceptors: Charge Redistribution Mechanisms
    • Authors: Melanie Timpel; Hong Li, Marco V. Nardi, Berthold Wegner, Johannes Frisch, Peter J. Hotchkiss, Seth R. Marder, Stephen Barlow, Jean-Luc Brédas, Norbert Koch
      Abstract: The uses of self-assembled monolayers (SAMs) of dipolar molecules or of adsorbed molecular acceptors on electrode materials are common strategies to increase their work function, thereby facilitating hole injection into an organic semiconductor deposited on top. Here it is shown that a combination of both approaches can surpass the performance of the individual ones. By combined experimental and theoretical methods it is revealed that in a three-component system, consisting of an indium-tin-oxide (ITO) electrode, a carbazole-based phosphonic acid SAM, and a molecular acceptor layer on top of the SAM, charge transfer occurs from the ITO through the SAM to the acceptor layer, resulting in an electrostatic field drop over the charge-neutral SAM. This result is in contrast to common expectations of either p-doping the carbazole of the SAM or charge transfer complex formation between the carbazole and the acceptor molecules. A high work function of 5.7 eV is achieved with this combined system; even higher values may be accessible by exploiting the fundamental charge redistribution mechanisms identified here with other material combinations.Electrode work function engineering by a combination of two approaches (self-assembled monolayer and adsorbed molecular acceptors) can potentially overcome the limitations of the individual ones. In the three-component system studied herein, charge transfer occurs from an indium-tin-oxide electrode through a self-assembled monolayer to a molecular acceptor layer atop, resulting in a high work function of 5.7 eV.
      PubDate: 2017-12-18T04:21:08.911594-05:
      DOI: 10.1002/adfm.201704438
       
  • Potential-Specific Structure at the Hematite–Electrolyte Interface
    • Authors: Martin E. McBriarty; Joanne E. Stubbs, Peter J. Eng, Kevin M. Rosso
      Abstract: The atomic-scale structure of the interface between a transition metal oxide and aqueous electrolyte regulates the interfacial chemical reactions fundamental to (photo)electrochemical energy conversion and electrode degradation. Measurements that probe oxide–electrolyte interfaces in situ provide important details of ion and solvent arrangements, but atomically precise structural models do not exist for common oxide–electrolyte interfaces far from equilibrium. Using a novel cell, the structure of the hematite (α-Fe2O3) (11¯02)–electrolyte interface is measured under controlled electrochemical bias using synchrotron crystal truncation rod X-ray scattering. At increasingly cathodic potentials, charge-compensating protonation of surface oxygen groups increases the coverage of specifically bound water while adjacent water layers displace outwardly and became disordered. Returning to open circuit potential leaves the surface in a persistent metastable state. Therefore, the flux of current and ions across the interface is regulated by multiple electrolyte layers whose specific structure and polarization change in response to the applied potential. The study reveals the complex environment underlying the simplified electrical double layer models used to interpret electrochemical measurements and emphasizes the importance of condition-specific structural characterization for properly understanding catalytic processes at functional transition metal oxide–electrolyte interfaces.Complex interfaces between iron oxides and aqueous electrolytes undergo dramatic changes under electrochemical bias. Cathodic poising of a hematite electrode modifies the near-surface electrolyte configuration, inhibiting mass transfer at the interface. This new experimental view of oxide–electrolyte interfaces poised far from equilibrium promises to advance molecular-scale models of photoelectrochemical water splitting, mineral dissolution/precipitation, and metal corrosion.
      PubDate: 2017-12-15T04:17:15.119495-05:
      DOI: 10.1002/adfm.201705618
       
  • Improving and Predicting Fluid Atomization via Hysteresis-Free Thickness
           Vibration of Lithium Niobate
    • Authors: Sean Collignon; Ofer Manor, James Friend
      Abstract: Acoustically driven atomization from the broad perspective of materials choice, vibration mode, and fluid characteristics is considered to identify a simple method for improving both the understanding of the atomization phenomena and the overall efficiency of atomization. Whether by the definition of a “figure of merit” (a function of the transducer quality factor and electromechanical coupling coefficient), its output vibration displacement at a given input power, or the fluid flow rate during atomization, it is found that the combination of single-crystal 127.86° Y-rotated lithium niobate and thickness-mode vibration produces an order of magnitude greater atomization flow rate and efficiency in comparison to all known atomizers, including classic lead zirconate-based devices and newer, Rayleigh wave or Rayleigh/Lamb spurious-mode-based devices alike. By using this improved approach, for the first time, fluids with viscosities up to 48 cP are reported to be atomized, and an atomization Reynolds number ReA is defined which can be used to both predict the atomization flow rate for ReA ≳ 40 and the inability to atomize a given fluid at a particular vibration amplitude when ReA ≲ 40.Through careful consideration of the materials and vibration in piezoelectric media, a counterintuitively superior method is discovered for efficiently and quickly atomizing even viscous fluids from a handheld nebulizer. Using a “figure of merit” defined in terms of the piezoelectric materials and vibration mode, the thickness mode in lithium niobate is found to offer superior atomizer capabilities.
      PubDate: 2017-12-07T05:59:21.813981-05:
      DOI: 10.1002/adfm.201704359
       
  • Stimuli-Responsive Nucleic Acid-Based Polyacrylamide Hydrogel-Coated
           Metal–Organic Framework Nanoparticles for Controlled Drug Release
    • Authors: Wei-Hai Chen; Wei-Ching Liao, Yang Sung Sohn, Michael Fadeev, Alessandro Cecconello, Rachel Nechushtai, Itamar Willner
      Abstract: The synthesis of doxorubicin-loaded metal–organic framework nanoparticles (NMOFs) coated with a stimuli-responsive nucleic acid-based polyacrylamide hydrogel is described. The formation of the hydrogel is stimulated by the crosslinking of two polyacrylamide chains, PA and PB, that are functionalized with two nucleic acid hairpins (4) and (5) using the strand-induced hybridization chain reaction. The resulting duplex-bridged polyacrylamide hydrogel includes the anti-ATP (adenosine triphosphate) aptamer sequence in a caged configuration. The drug encapsulated in the NMOFs is locked by the hydrogel coating. In the presence of ATP that is overexpressed in cancer cells, the hydrogel coating is degraded via the formation of the ATP–aptamer complex, resulting in the release of doxorubicin drug. In addition to the introduction of a general means to synthesize drug-loaded stimuli-responsive nucleic acid-based polyacrylamide hydrogel-coated NMOFs hybrids, the functionalized NMOFs resolve significant limitations associated with the recently reported nucleic acid-gated drug-loaded NMOFs. The study reveals substantially higher loading of the drug in the hydrogel-coated NMOFs as compared to the nucleic acid-gated NMOFs and overcomes the nonspecific leakage of the drug observed with the nucleic-acid-protected NMOFs. The doxorubicin-loaded, ATP-responsive, hydrogel-coated NMOFs reveal selective and effective cytotoxicity toward MDA-MB-231 breast cancer cells, as compared to normal MCF-10A epithelial breast cells.A stimuli-responsive nucleic acid-based hydrogel coating drug-loaded metal–organic framework nanoparticles (NMOF) acts as an effective carrier for controlled drug release. This is exemplified with ATP (adenosine triphosphate)-responsive hydrogel-coated NMOFs loaded with doxorubicin. In the presence of ATP, overexpressed in cancer cells, the hydrogel coating is dissociated, resulting in the release of the drug. The hybrid NMOFs reveal selective cytotoxicity toward MDA-MB-231 breast cancer cells.
      PubDate: 2017-12-04T02:26:16.40096-05:0
      DOI: 10.1002/adfm.201705137
       
 
 
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