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  Subjects -> CHEMISTRY (Total: 848 journals)
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CHEMISTRY (602 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 5)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 25)
ACS Catalysis     Full-text available via subscription   (Followers: 29)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 21)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 37)
ACS Nano     Full-text available via subscription   (Followers: 189)
ACS Photonics     Full-text available via subscription   (Followers: 7)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 20)
Acta Chemica Iasi     Open Access   (Followers: 1)
Acta Chimica Sinica     Full-text available via subscription  
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 1)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 6)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 4)
Advanced Functional Materials     Hybrid Journal   (Followers: 45)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 52)
Advances in Chemical Science     Open Access   (Followers: 11)
Advances in Chemistry     Open Access   (Followers: 11)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 17)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Enzyme Research     Open Access   (Followers: 6)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 12)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 16)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 14)
Advances in Polymer Science     Hybrid Journal   (Followers: 39)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 16)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 7)
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)
Alchemy : Jurnal Penelitian 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: 64)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 24)
American Journal of Plant Physiology     Open Access   (Followers: 12)
American Mineralogist     Full-text available via subscription   (Followers: 8)
Anadolu University Journal of Science and Technology     Open Access  
Analyst     Full-text available via subscription   (Followers: 42)
Angewandte Chemie     Hybrid Journal   (Followers: 139)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 190)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 3)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 7)
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: 14)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 6)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 23)
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: 3)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 6)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 9)
Biochemistry     Full-text available via subscription   (Followers: 244)
Biochemistry Insights     Open Access   (Followers: 5)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 3)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 17)
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: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 111)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 100)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 17)
Biosensors     Open Access   (Followers: 1)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 3)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 26)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 2)
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 8)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 65)
Catalysis for Sustainable Energy     Open Access   (Followers: 5)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 6)
Cellulose     Hybrid Journal   (Followers: 5)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 7)
Chemical and Engineering News     Free   (Followers: 10)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 70)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 22)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 18)
Chemical Reviews     Full-text available via subscription   (Followers: 148)
Chemical Science     Open Access   (Followers: 19)
Chemical Technology     Open Access   (Followers: 13)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemical Week     Full-text available via subscription   (Followers: 7)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 53)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
ChemInform     Hybrid Journal   (Followers: 7)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 4)
Chemistry - A European Journal     Hybrid Journal   (Followers: 125)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 14)
Chemistry and Materials Research     Open Access   (Followers: 15)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 4)
Chemistry in Education     Open Access   (Followers: 3)
Chemistry International     Hybrid Journal   (Followers: 1)
Chemistry Letters     Full-text available via subscription   (Followers: 45)
Chemistry of Materials     Full-text available via subscription   (Followers: 159)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 8)
ChemPlusChem     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography Research International     Open Access   (Followers: 5)
Clay Minerals     Full-text available via subscription   (Followers: 8)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 10)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 3)
Combustion Science and Technology     Hybrid Journal   (Followers: 18)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Composite Interfaces     Hybrid Journal   (Followers: 5)
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  
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 2)
CrystEngComm     Full-text available via subscription   (Followers: 10)
Current Catalysis     Hybrid Journal   (Followers: 1)
Current Metabolomics     Hybrid Journal   (Followers: 3)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 8)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 15)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 46)
Dalton Transactions     Full-text available via subscription   (Followers: 18)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 11)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 3)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 2)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
EDUSAINS     Open Access  
Elements     Full-text available via subscription   (Followers: 1)
Environmental Chemistry     Hybrid Journal   (Followers: 5)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 2)

        1 2 3 4 | Last

Journal Cover Advanced Functional Materials
  [SJR: 5.21]   [H-I: 203]   [45 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  [1605 journals]
  • Direct Synthesis of Large-Scale WTe2 Thin Films with Low Thermal
           Conductivity
    • Authors: Yu Zhou; Hyejin Jang, John M. Woods, Yujun Xie, Piranavan Kumaravadivel, Grace A. Pan, Jingbei Liu, Yanhui Liu, David G. Cahill, Judy J. Cha
      Abstract: Large-scale, polycrystalline WTe2 thin films are synthesized by atmospheric chemical vapor reaction of W metal films with Te vapor catalyzed by H2Te intermediates, paving a way to understanding the synthesis mechanism for low bonding energy tellurides and toward synthesis of single-crystalline telluride nanoflakes. Through-plane and in-plane thermal conductivities of single-crystal WTe2 flakes and polycrystalline WTe2 thin films are measured for the first time. Nanoscale grains and disorder in WTe2 thin films suppress the in-plane thermal conductivity of WTe2 greatly, which is at least 7.5 times lower than that of the single-crystalline flakes.Large-scale, polycrystalline WTe2 thin films are synthesized by atmospheric chemical vapor reaction of W metal films with Te vapor catalyzed by H2Te intermediates, paving a way to understanding the synthesis mechanism for low bonding energy tellurides and toward synthesis of single-crystalline telluride nanoflakes. Through-plane and in-plane thermal conductivities of single-crystal WTe2 flakes and polycrystalline WTe2 thin films are measured for the first time. Nanoscale grains and disorder in WTe2 thin films suppress the in-plane thermal conductivity of WTe2 greatly, which is at least 7.5 times lower than that of the single-crystalline flakes.
      PubDate: 2017-01-13T07:45:46.032677-05:
      DOI: 10.1002/adfm.201605928
       
  • Stabilization of Single Metal Atoms on Graphitic Carbon Nitride
    • Authors: Zupeng Chen; Sharon Mitchell, Evgeniya Vorobyeva, Rowan K. Leary, Roland Hauert, Tom Furnival, Quentin M. Ramasse, John M. Thomas, Paul A. Midgley, Dariya Dontsova, Markus Antonietti, Sergey Pogodin, Núria López, Javier Pérez-Ramírez
      Abstract: Graphitic carbon nitride (g-C3N4) exhibits unique properties as a support for single-atom heterogeneous catalysts (SAHCs). Understanding how the synthesis method, carrier properties, and metal identity impact the isolation of metal centers is essential to guide their design. This study compares the effectiveness of direct and postsynthetic routes to prepare SAHCs by incorporating palladium, silver, iridium, platinum, or gold in g-C3N4 of distinct morphology (bulk, mesoporous and exfoliated). The speciation (single atoms, dimers, clusters, or nanoparticles), distribution, and oxidation state of the supported metals are characterized by multiple techniques including extensive use of aberration-corrected electron microscopy. SAHCs are most readily attained via direct approaches applying copolymerizable metal precursors and employing high surface area carriers. In contrast, although post-synthetic routes enable improved control over the metal loading, nanoparticle formation is more prevalent. Comparison of the carrier morphologies also points toward the involvement of defects in stabilizing single atoms. The distinct metal dispersions are rationalized by density functional theory and kinetic Monte Carlo simulations, highlighting the interplay between the adsorption energetics and diffusion kinetics. Evaluation in the continuous three-phase semihydrogenation of 1-hexyne identifies controlling the metal–carrier interaction and exposing the metal sites at the surface layer as key challenges in designing efficient SAHCs.Criteria are identified for preparing single-atom heterogeneous catalysts based on carbon nitride. The impact of the synthesis route, carrier morphology, and metal identity on the speciation is determined using characterizations and simulations. Direct synthesis exploiting copolymerizable metal precursors, high mesoporosity, and the presence of defects favor the stabilization of metal atoms, but post-synthesis approaches yield enhanced accessibility in catalyzed reactions.
      PubDate: 2017-01-13T07:45:40.890055-05:
      DOI: 10.1002/adfm.201605785
       
  • Energy-Dissipative Matrices Enable Synergistic Toughening in Fiber
           Reinforced Soft Composites
    • Authors: Yiwan Huang; Daniel R. King, Tao Lin Sun, Takayuki Nonoyama, Takayuki Kurokawa, Tasuku Nakajima, Jian Ping Gong
      Abstract: Tough hydrogels have shown strong potential as structural biomaterials. These hydrogels alone, however, possess limited mechanical properties (such as low modulus) when compared to some load-bearing tissues, e.g., ligaments and tendons. Developing both strong and tough soft materials is still a challenge. To overcome this obstacle, a new material design strategy has been recently introduced by combining tough hydrogels with woven fiber fabric to create fiber reinforced soft composites (FRSCs). The new FRSCs exhibit extremely high toughness and tensile properties, far superior to those of the neat components, indicating a synergistic effect. Here, focus is on understanding the role of energy dissipation of the soft matrix in the synergistic toughening of FRSCs. By selecting a range of soft matrix materials, from tough hydrogels to weak hydrogels and even a commercially available elastomer, the toughness of the matrix is determined to play a critical role in achieving extremely tough FRSCs. This work provides a good guide toward the universal design of soft composites with extraordinary fracture resistance capacity.The critical role of energy dissipation of a soft matrix is understood in the synergistic toughening of fiber reinforced composites. The composite toughness (Tc) follows an empirical power-law equation, Tc = 220 Tm0.64, over two orders of magnitude of the soft matrix toughness (Tm). This study provides a good guide for the universal design of extremely tough soft composite materials.
      PubDate: 2017-01-13T07:41:19.294026-05:
      DOI: 10.1002/adfm.201605350
       
  • Unraveling Surface Basicity and Bulk Morphology Relationship on Covalent
           Triazine Frameworks with Unique Catalytic and Gas Adsorption Properties
    • Authors: Giulia Tuci; Moritz Pilaski, Housseinou Ba, Andrea Rossin, Lapo Luconi, Stefano Caporali, Cuong Pham-Huu, Regina Palkovits, Giuliano Giambastiani
      Abstract: Activity and selectivity are key features at the basis of an efficient catalytic system for promoting the steam- and oxygen-free dehydrogenation (DDH) of ethylbenzene to styrene. The catalyst stability under severe reaction conditions, the reduction of leaching of its active sites, and their resistance to deactivation phenomena on stream are other fundamental aspects to keep in mind while synthesizing new catalytic materials for the process. Although the recent use of single-phase (doped or undoped) carbon nanomaterials has significantly contributed to improving this catalysis, the relationship between materials morphology and their chemical surface properties still remains to be addressed. Here, a class of highly microporous, N-doped covalent triazine frameworks (CTFs) with superior activity and stability in the DDH compared to the benchmark systems of the state-of-the-art is reported. Notably, a comparative analysis of their chemico-physical properties has unveiled the role of the “chemically accessible” surface basicity on the catalyst passivation on stream. Finally, the unique properties of the synthesized CTFs are demonstrated by their excellent H2 storage capability and CO2 absorption that rank among the highest reported so far for related systems.Highly microporous N-doped covalent triazine frameworks show superior activity and stability in the ethylbenzene dehydrogenation to styrene compared to state-of-the-art benchmark systems. Their unique chemico-physical properties also demonstrate their superior H2 storage capability as well as their CO2 absorption that ranks among the highest reported so far for related systems.
      PubDate: 2017-01-13T07:41:15.100241-05:
      DOI: 10.1002/adfm.201605672
       
  • Electronic and Optical Properties of a Semiconducting Spinel (Fe2CrO4)
    • Authors: Scott A. Chambers; Timothy C. Droubay, Tiffany C. Kaspar, Iffat H. Nayyar, Martin E. McBriarty, Steve M. Heald, David J. Keavney, Mark E. Bowden, Peter V. Sushko
      Abstract: Epitaxial chromium ferrite (Fe2CrO4), prepared by state-of-the-art oxygen plasma assisted molecular beam epitaxy, is shown to exhibit unusual electronic transport properties driven by the crystallographic structure and composition of the material. Replacing 1/3 of the Fe cations with Cr converts the host ferrimagnet from a metal into a semiconductor by virtue of its fixed valence (3+); Cr substitutes for Fe at B sites in the spinel lattice. By contrast, replacing 2/3 of the Fe cations with Cr results in an insulator. Three candidate conductive paths, all involving electron hopping between Fe2+ and Fe3+, are identified in Fe2CrO4. Moreover, Fe2CrO4 is shown to be photoconductive across the visible portion of the electromagnetic spectrum. As a result, this material is of potential interest for important photo-electrochemical processes such as water splitting.A qualitatively different mode of conductivity is activated in magnetite by doping one third of the Fe cation sites with Cr. Experimental data and ab initio modeling results establish the structure, and then point to different electron hopping paths becoming operative, as Cr3+ replaces Fe3+ in the octahedral sites of the spinel lattice.
      PubDate: 2017-01-13T07:41:11.990228-05:
      DOI: 10.1002/adfm.201605040
       
  • Rock Salt Ni/Co Oxides with Unusual Nanoscale-Stabilized Composition as
           Water Splitting Electrocatalysts
    • Authors: Ksenia Fominykh; Gülen Ceren Tok, Patrick Zeller, Hamidreza Hajiyani, Thomas Miller, Markus Döblinger, Rossitza Pentcheva, Thomas Bein, Dina Fattakhova-Rohlfing
      Abstract: The influence of nanoscale on the formation of metastable phases is an important aspect of nanostructuring that can lead to the discovery of unusual material compositions. Here, the synthesis, structural characterization, and electrochemical performance of Ni/Co mixed oxide nanocrystals in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is reported and the influence of nanoscaling on their composition and solubility range is investigated. Using a solvothermal synthesis in tert-butanol ultrasmall crystalline and highly dispersible NixCo1−xO nanoparticles with rock salt type structure are obtained. The mixed oxides feature non-equilibrium phases with unusual miscibility in the whole composition range, which is attributed to a stabilizing effect of the nanoscale combined with kinetic control of particle formation. Substitutional incorporation of Co and Ni atoms into the rock salt lattice has a remarkable effect on the formal potentials of NiO oxidation that shift continuously to lower values with increasing Co content. This can be related to a monotonic reduction of the work function of (001) and (111)-oriented surfaces with an increase in Co content, as obtained from density functional theory (DFT+U) calculations. Furthermore, the electrocatalytic performance of the NixCo1−xO nanoparticles in water splitting changes significantly. OER activity continuously increases with increasing Ni contents, while HER activity shows an opposite trend, increasing for higher Co contents. The high electrocatalytic activity and tunable performance of the nonequilibrium NixCo1−xO nanoparticles in HER and OER demonstrate great potential in the design of electrocatalysts for overall water splitting.Ultrasmall crystalline Ni/Co mixed oxide nanoparticles with unusual miscibility in the whole composition range are prepared. Their unusual properties are attributed to a stabilizing effect of the nanoscale combined with kinetic control of particle formation. The particles demonstrate tunable electrocatalytic activity in both the hydrogen and oxygen evolution reaction depending on the relative amount of cobalt and nickel.
      PubDate: 2017-01-13T07:41:08.589593-05:
      DOI: 10.1002/adfm.201605121
       
  • Ultrathin-Nanosheet-Induced Synthesis of 3D Transition Metal Oxides
           Networks for Lithium Ion Battery Anodes
    • Authors: Shan Zhu; Jiajun Li, Xiaoyang Deng, Chunnian He, Enzuo Liu, Fang He, Chunsheng Shi, Naiqin Zhao
      Abstract: A general ultrathin-nanosheet-induced strategy for producing a 3D mesoporous network of Co3O4 is reported. The fabrication process introduces a 3D N-doped carbon network to adsorb metal cobalt ions via dipping process. Then, this carbon matrix serves as the sacrificed template, whose N-doping effect and ultrathin nanosheet features play critical roles for controlling the formation of Co3O4 networks. The obtained material exhibits a 3D interconnected architecture with large specific surface area and abundant mesopores, which is constructed by nanoparticles. Merited by the optimized structure in three length scales of nanoparticles–mesopores–networks, this Co3O4 nanostructure possesses superior performance as a LIB anode: high capacity (1033 mAh g−1 at 0.1 A g−1) and long-life stability (700 cycles at 5 A g−1). Moreover, this strategy is verified to be effective for producing other transition metal oxides, including Fe2O3, ZnO, Mn3O4, NiCo2O4, and CoFe2O4.A general ultrathin-nanosheet-induced strategy is introduced for producing 3D mesoporous network of transition metal oxides (TMOs). An N-doped carbon network serves as the sacrificed template, which can be applied to many kinds of TMOs. The obtained material exhibits an interconnected mesopore architecture and possesses superior performance as a lithium ion anode.
      PubDate: 2017-01-13T07:41:03.942179-05:
      DOI: 10.1002/adfm.201605017
       
  • A Biomimetic Mussel-Inspired ε-Poly-l-lysine Hydrogel with Robust
           Tissue-Anchor and Anti-Infection Capacity
    • Authors: Rui Wang; Jingzhe Li, Wei Chen, Tingting Xu, Shifeng Yun, Zheng Xu, Zongqi Xu, Takashi Sato, Bo Chi, Hong Xu
      Abstract: In situ hydrogels have attracted considerable attention in tissue engineering because of their minimal invasiveness and ability to match the irregular tissue defects. However, hydrous physiological environments and the high level of moisture in hydrogels severely hamper binding to the target tissue and easily cause wound infection, thereby limiting the effectiveness in wound care management. Thus, forming an intimate assembly of the hydrogel to the tissue and preventing wound infecting still remains a significant challenge. In this study, inspired by mussel adhesive protein, a biomimetic dopamine-modified ε-poly-l-lysine-polyethylene glycol-based hydrogel (PPD hydrogel) wound dressing is developed in situ using horseradish peroxidase cross-linking. The biomimetic catechol–Lys residue distribution in PPD polymer provides a catechol–Lys cooperation effect, which endows the PPD hydrogels with superior wet tissue adhesion properties. It is demonstrated that the PPD hydrogel can facilely and intimately integrate with biological tissue and exhibits superior capacity of in vivo hemostatic and accelerated wound repair. In addition, the hydrogels exhibit outstanding anti-infection property because of the inherent antibacterial ability of ε-poly-l-lysine. These findings shed new light on the development of mussel-inspired tissue-anchored and antibacterial hydrogel materials serving as wound dressings.A new enzyme cross-linking method for the fabrication of biomimetic mfp-5 analogue hydrogels (i.e., ε-poly-l-lysine-polyethylene glycol-based hydrogels) is demonstrated. The resulting hydrogel possesses robust tissue-anchor and superior anti-infection performance. A new platform for designing mussel-inspired materials by coupling catechol and cationic functionalities is developed.
      PubDate: 2017-01-13T07:40:58.341736-05:
      DOI: 10.1002/adfm.201604894
       
  • Strong Facet Effects on Interfacial Charge Transfer Revealed through the
           Examination of Photocatalytic Activities of Various Cu2O–ZnO
           Heterostructures
    • Authors: Szu-Chieh Wu; Chih-Shan Tan, Michael H. Huang
      Abstract: Confirming the photocatalytic inactivity of Cu2O nanocubes through the formation of Au-decorated–Cu2O heterostructures, spiky ZnO nanostructures are grown on Cu2O cubes, octahedra, and rhombic dodecahedra to demonstrate that charge transfer across semiconductor heterojunctions is also strongly facet dependent. Unintended CuO formation in the growth of ZnO on perfect Cu2O cubes makes them slightly active toward methyl orange photodegradation. Under optimal ZnO growth conditions without CuO presence, Cu2O cubes remain inactive, while rhombic dodecahedra show an enhanced photocatalytic activity due to better charge transfer according to normal Cu2O–ZnO band alignment. Surprisingly, photocatalytically active Cu2O octahedra become inactive after ZnO deposition. An extensive interfacial microscopic examination reveals preferential formation of the ZnO (101) planes on the {111} surfaces of Cu2O octahedra, while different ZnO lattice planes are observed to deposit on Cu2O cubes and rhombic dodecahedra. The photocatalytic inactivity of ZnO-decorated Cu2O octahedra is explained in terms of an unfavorable band alignment arising from an unusual degree of band bending for the ZnO {101} face relative to the band energy of the Cu2O {111} surface. The efficiency of charge transfer across semiconductor heterojunctions strongly depends on the band edge energies of the contacting planes.Formation of Cu2O–ZnO heterostructures can enhance or completely suppress photoinduced charge carrier transfer depending on the contacting facets or planes. Simple band alignment analysis of semiconductor heterojunctions without consideration of facet effects is insufficient in predicting photocatalytic behaviors. The photocatalytic activity of Cu2O octahedra is lost after preferential growth of (101) planes of ZnO.
      PubDate: 2017-01-13T07:40:49.697256-05:
      DOI: 10.1002/adfm.201604635
       
  • Significant Enhancement of Proton Transport in Bioinspired Peptide Fibrils
           by Single Acidic or Basic Amino Acid Mutation
    • Authors: Ohad Silberbush; Moran Amit, Subhasish Roy, Nurit Ashkenasy
      Abstract: Bioinspired materials are extremely suitable for the development of biocompatible and environmentally friendly functional materials. Peptide-based assemblies are remarkably attractive for such tasks, since they provide a simple way to fuse together functional and structural protein motifs in artificial materials. Motivated by this idea, it is shown here that the introduction of a single acidic, or basic, amino acid into the side chain of a heptameric self-assembling peptide increases proton conduction in the resulting fibers by two orders of magnitude. This self-doping effect is much more pronounced than the effect induced by the peptide's acidic and basic termini groups. Furthermore, the self-doping process is found to be significantly more effective for acidic side chains than for basic ones due to both much more effective self-doping process, resulting in an order of magnitude larger concentration of charge carriers for the acidic assemblies, and higher mobility of the formed charge carriers – almost threefolds in this case. This work facilitates the realization of unique bioinspired self-assembled proton conducting materials that may find uses in the emerging bioprotonic technology. The presented design flexibility and, in particular, the ability to introduce both proton and proton holes further extend the usefulness of these materials.Efficient proton self-doping is induced in peptide self-assembled fibrils by the introduction of amino acids with acidic or basic functionality. This effect is found to be much more pronounced for acidic groups, and together with higher mobility of the charge carriers, results in much over an order of magnitude greater conductivity for the acidic fibrils.
      PubDate: 2017-01-13T07:40:41.416536-05:
      DOI: 10.1002/adfm.201604624
       
  • Photopicking: In Situ Approach for Site-Specific Attachment of Single
           Multiprotein Nanoparticles to Atomic Force Microscopy Tips
    • Authors: Ivan Liashkovich; Gonzalo Rosso, Martina Rangl, Andreas Ebner, Wali Hafezi, Joachim Kühn, Peter Schön, Peter Hinterdorfer, Victor Shahin
      Abstract: Ligand–receptor interactions are fundamental in life sciences and include hormone–receptor, protein–protein, pathogen–host, and cell–cell interactions, among others. Atomic force microscopy (AFM) proved to be invaluable for scrutinizing ligand–receptor interactions at the single molecular level. Basically, a ligand is attached to the AFM tip while its cognate receptor is immobilized on a surface or vice versa, and interactions are studied following triggered ligand–receptor binding. However, with rising biological complexity it becomes increasingly challenging to attach a single intact biomolecule to the tip and ensure interaction-specific orientation. This study presents a novel strategy of inducible in situ tip functionalization with complex multiprotein nanoparticles exemplified by viral capsids, termed photopicking. It ensures a firm attachment of single 125 nm large capsids to the tip. Specific orientation is attained by weak immunosorption of capsids to the substrate and strong photoinducible covalent cross-linking to the tip. Validation of the tip functionalization success is immediate in situ. The versatility of the strategy is further demonstrated on 20–60 nm large amino-modified nanoparticles. In conclusion, considering the size range of the tested biomolecules, the presented strategy is applicable to viruses, viral particles, cellular organelles, multiprotein ligands/receptors, and therapeutic nanoparticles, among others. It therefore opens up exciting new avenues in broad biomedical research fields.A schematic of the photopicking approach to pick up a single multiprotein nanoparticle is given, exemplified by a viral capsid with a site-specific orientation.
      PubDate: 2017-01-13T07:40:34.073503-05:
      DOI: 10.1002/adfm.201604506
       
  • Anomalous Channel-Length Dependence in Nanofluidic Osmotic Energy
           Conversion
    • Authors: Liuxuan Cao; Feilong Xiao, Yaping Feng, Weiwei Zhu, Wenxiao Geng, Jinlei Yang, Xiaopeng Zhang, Ning Li, Wei Guo, Lei Jiang
      Abstract: Recent advances in materials science and nanotechnology have lead to considerable interest in constructing ion-channel-mimetic nanofluidic systems for energy conversion and storage. The conventional viewpoint suggests that to gain high electrical energy, the longitudinal dimension of the nanochannels (L) should be reduced so as to bring down the resistance for ion transport and provide high ionic flux. Here, counterintuitive channel-length dependence is described in nanofluidic osmotic power generation. For short nanochannels (with length L < 400 nm), the converted electric power persistently decreases with the decreasing channel length, showing an anomalous, non-Ohmic response. The combined thermodynamic analysis and numerical simulation prove that the excessively short channel length impairs the charge selectivity of the nanofluidic channels and induces strong ion concentration polarization. These two factors eventually undermine the osmotic power generation and its energy conversion efficiency. Therefore, the optimal channel length should be between 400 and 1000 nm in order to maximize the electric power, while balancing the efficiency. These findings reveal the importance of a long-overlooked element, the channel length, in nanofluidic energy conversion and provide guidance to the design of high-performance nanofluidic energy devices.Anomalous channel-length dependence is discovered in nanofluidic osmotic power generation. In contrast to conventional long nanofluidic devices, if the channel length is further reduced to below 400 nm, the output power decreases with decreasing channel length, showing anomalous, non-Ohmic response. These findings reveal the importance of the long-overlooked element, the channel length, in nanofluidic energy conversion.
      PubDate: 2017-01-13T07:30:51.443864-05:
      DOI: 10.1002/adfm.201604302
       
  • Controllable Crystallization of CH3NH3Sn0.25Pb0.75I3 Perovskites for
           Hysteresis-Free Solar Cells with Efficiency Reaching 15.2%
    • Authors: Hugh Lu Zhu; Junyan Xiao, Jian Mao, Hong Zhang, Yong Zhao, Wallace C. H. Choy
      Abstract: While SnPb alloyed perovskites have been considered as an effective approach to broaden the absorption spectrum, it is still challenging to modify the crystallization (and thus morphology, crystallinity, and orientation) in a controllable manner and thus boost the efficiency of SnPb alloyed perovskite solar cells. Here, it is unveiled that controlling the crystallization of CH3NH3Sn0.25Pb0.75I3 films can be simply realized by adjusting the amount of dimethyl sulfoxide in precursors, which has not been reported in SnPb alloyed perovskite systems. The remarkable perovskite crystallinity enhancement by the 20-fold enhanced (110) plane intensity in the X-ray diffraction spectrum of CH3NH3Sn0.25Pb0.75I3 and the preferred (110) orientation with the texture coefficient enhanced by 2.6 times to reach 0.88 are demonstrated. Importantly, it is discovered that the introduction of dimethyl sulfoxide avoids the formation of the colloidal coagulation observed in prolonged-storage precursors and ameliorates inhomogeneous Sn/Pb distributions in resultant perovskite films. Through optimizing perovskite films and device structures, hysteresis-free planar-heterojunction CH3NH3Sn0.25Pb0.75I3 solar cells with the efficiency reaching 15.2%, which are the most efficient SnPb alloy-based perovskite solar cells, are achieved.CH3NH3Sn0.25Pb0.75I3 films with enhanced crystallinity, preferred orientation, and ameliorated inhomogeneous Sn/Pb distributions are realized by the controllable crystallization via the introduction of dimethyl sulfoxide. Optimized planar-heterojunction CH3NH3Sn0.25Pb0.75I3-based solar cells achieve the power conversion efficiency of 15.2% and no hysteresis, which is the highest value among SnPb alloy-based perovskite solar cells.
      PubDate: 2017-01-12T09:10:57.659441-05:
      DOI: 10.1002/adfm.201605469
       
  • Unexpected Sole Enol-Form Emission of 2-(2′-Hydroxyphenyl)oxazoles for
           Highly Efficient Deep-Blue-Emitting Organic Electroluminescent Devices
    • Authors: Bijin Li; Guoqiang Tang, Linsen Zhou, Di Wu, Jingbo Lan, Liang Zhou, Zhiyun Lu, Jingsong You
      Abstract: Considerable efforts have been devoted to the development of highly efficient blue light-emitting materials. However, deep-blue fluorescence materials that can satisfy the Commission Internationale de l'Eclairage (CIE) coordinates of (0.14, 0.08) of the National Television System Committee (NTSC) standard blue and, moreover, possess a high external quantum efficiency (EQE) over 5%, remain scarce. Here, the unusual luminescence properties of triphenylamine-bearing 2-(2′-hydroxyphenyl)oxazoles (3a–3c) and their applications in organic light-emitting diodes (OLEDs) are reported as highly efficient deep-blue emitters. The 3a-based device exhibits a high spectral stability and an excellent color purity with a narrow full-width at half-maximum of 53 nm and the CIE coordinates of (0.15, 0.08), which is very close to the NTSC standard blue. The exciton utilization of the device closes to 100%, exceeding the theoretical limit of 25% in conventional fluorescent OLEDs. Experimental data and theoretical calculations demonstrate that 3a possesses a highly hybridized local and charge-transfer excited state character. In OLEDs, 3a exhibits a maximum luminance of 9054 cd m−2 and an EQE up to 7.1%, which is the first example of highly efficient blue OLEDs based on the sole enol-form emission of 2-(2′-hydroxyphenyl)azoles.The unusual sole enol-form emission of 2-(2′-hydroxyphenyl)oxazoles and their application in organic light-emitting diodes (OLEDs) have been investigated. The device exhibits an excellent color purity, a spectral stability, and an external quantum efficiency up to 7.1%, which is the first example of highly efficient blue OLEDs based on the sole enol-form emission of 2-(2′-hydroxyphenyl)azoles.
      PubDate: 2017-01-12T09:10:42.203026-05:
      DOI: 10.1002/adfm.201605245
       
  • Printable and Flexible Phototransistors Based on Blend of Organic
           Semiconductor and Biopolymer
    • Authors: Jia Huang; Juan Du, Zehra Cevher, Yuhang Ren, Xiaohan Wu, Yingli Chu
      Abstract: Printable and flexible organic phototransistors (OPTs) make comprehensive requirements for the organic semiconductors (OSCs), including high photosensitivity, decent transistor characteristics, appropriate solution viscosity, and good film flexibility. It has been challenging to obtain such semiconductors. Here, we demonstrated that by taking advantage of the interfacial charge effect, printable and flexible OPTs with high performance can be successfully fabricated through simply blending common OSCs with polymers. Using 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene and an insulating biopolymer polylactide, OPTs with blended and layered structure are both fabricated and investigated. The photoresponses of the OPTs can be modulated by gate voltage over 1000 times, and their responsivities are measured up to 400 A W−1. As compared to the layered OPTs, the blended ones exhibit higher photocurrent to dark current ratio (up to 105) and better light detection limit (lower than 0.02 mW cm−2). The improvements are attributed to larger interfacial area and more intensive charge trapping effect. The flexible OPTs are further fabricated by inkjet printing the blended solution. This work presents OPTs with comprehensive advantages including low cost, enhanced photosensitivity, great flexibility, and printability, which are realized by simply blending common OSC with polymer, and thus provide an inspiration for the design of novel organic electronics.Printable, flexible, and low-cost organic phototransistors are fabricated by simply blending a common organic semiconductor with a biopolymer. The device exhibits great photosensitivity by taking advantage of organic semiconductor/polymer interfacial charge effect. The phototransistor with blended structure shows better photosensitivity, e.g., higher photogenerated to dark current ratio up to 105 than that with layered structure due to larger interfacial area.
      PubDate: 2017-01-12T09:10:36.327297-05:
      DOI: 10.1002/adfm.201604163
       
  • A Generic Conversion Strategy: From 2D Metal Carbides (MxCy) to
           M-Self-Doped Graphene toward High-Efficiency Energy Applications
    • Authors: Zongkui Kou; Tian Meng, Beibei Guo, Ibrahim Saana Amiinu, Wenqiang Li, Jie Zhang, Shichun Mu
      Abstract: This study first presents a subtle thermal-chlorination strategy for a universal transformation of abundant 2D metal carbides (MxCy, e.g., Cr3C2, Mo2C, NbC, and VC) to 2D graphene and M-self-doped graphene (MG). The as-obtained MG endows a transparent sheet architecture of one to four atomic layers. Simultaneously, MG with different M amounts is synthesized by tuning the chlorination parameters. Among them, the novel and representative Cr-self-doped graphene with optimal Cr amount (4.81 at%) demonstrates the outstanding electrochemical performance. It presents an energy density of 686 W h per kg electrode and a power density of more than 391 W per kg electrode as anode material of Li ion batteries, and four-fold activity against the commercial iridium oxide electrode toward oxygen evolution reaction as well as a comparable oxygen reduction reaction performance to the commercial platinum catalyst. Moreover, this method is readily scalable to produce graphene and MG electrode materials on industrial levels.For the first time, graphene and its derivative metal-self-doped graphene (MG) are obtained by a universal technique to thermal chlorination of 2D metal carbides (MxCy). Comparing with top nonmetallic atoms-doped graphene, particular MG demonstrates superb Li-storage properties as anode of LIBs and catalyticalctivities for oxygen reduction and evolution reactions.
      PubDate: 2017-01-11T05:40:40.498869-05:
      DOI: 10.1002/adfm.201604904
       
  • Engineered Extracellular Matrices as Biomaterials of Tunable Composition
           and Function
    • Authors: Paul Emile Bourgine; Emanuele Gaudiello, Benjamin Pippenger, Claude Jaquiery, Thibaut Klein, Sebastien Pigeot, Atanas Todorov, Sandra Feliciano, Andrea Banfi, Ivan Martin
      Abstract: Engineered and decellularized extracellular matrices (ECM) are receiving increasing interest in regenerative medicine as materials capable to induce cell growth/differentiation and tissue repair by physiological presentation of embedded cues. However, ECM production/decellularization processes and control over their composition remain primary challenges. This study reports engineering of ECM materials with customized properties, based on genetic manipulation of immortalized and death-inducible human mesenchymal stromal cells (hMSC), cultured within 3D porous scaffolds under perfusion flow. The strategy allows for robust ECM deposition and subsequent decellularization by deliberate cell-apoptosis induction. As compared to standard production and freeze/thaw treatment, this grants superior preservation of ECM, leading to enhanced bone formation upon implantation in calvarial defects. Tunability of ECM composition and function is exemplified by modification of the cell line to overexpress vascular endothelial growth factor alpha (VEGF), which results in selective ECM enrichment and superior vasculature recruitment in an ectopic implantation model. hMSC lines culture under perfusion-flow is pivotal to achieve uniform scaffold decoration with ECM and to streamline the different engineering/decellularization phases in a single environmental chamber. The findings outline the paradigm of combining suitable cell lines and bioreactor systems for generating ECM-based off-the-shelf materials, with custom set of signals designed to activate endogenous regenerative processes.The biological functionality of scaffold materials can be enhanced and customized by decoration with cell-laid extracellular matrix (ECM). As proof-of-principle of the concept, a death-inducible mesenchymal stromal cell line (MSOD), or its counterpart overexpressing VEGF, are cultured under perfusion flow and induced to apoptosis. The resulting decellularized, customized ECM grafts are used to regenerate bone tissue or to enhance vascularization.
      PubDate: 2017-01-11T05:35:53.670099-05:
      DOI: 10.1002/adfm.201605486
       
  • Design of Hierarchical NiCo@NiCo Layered Double Hydroxide Core–Shell
           Structured Nanotube Array for High-Performance Flexible All-Solid-State
           Battery-Type Supercapacitors
    • Authors: Yan Liu; Nianqing Fu, Guoge Zhang, Ming Xu, Wei Lu, Limin Zhou, Haitao Huang
      Abstract: A novel hierarchical nanotube array (NTA) with a massive layered top and discretely separated nanotubes in a core–shell structure, that is, nickel–cobalt metallic core and nickel–cobalt layered double hydroxide shell (NiCo@NiCo LDH), is grown on carbon fiber cloth (CFC) by template-assisted electrodeposition for high-performance supercapacitor application. The synthesized NiCo@NiCo LDH NTAs/CFC shows high capacitance of 2200 F g−1 at a current density of 5 A g−1, while 98.8% of its initial capacitance is retained after 5000 cycles. When the current density is increased from 1 to 20 A g−1, the capacitance loss is less than 20%, demonstrating excellent rate capability. A highly flexible all-solid-state battery-type supercapacitor is successfully fabricated with NiCo LDH NTAs/CFC as the positive electrode and electrospun carbon fibers/CFC as the negative electrode, showing a maximum specific capacitance of 319 F g−1, a high energy density of 100 W h kg−1 at 1.5 kW kg−1, and good cycling stability (98.6% after 3000 cycles). These fascinating electrochemical properties are resulted from the novel structure of electrode materials and synergistic contributions from the two electrodes, showing great potential for energy storage applications.Hierarchical nickel–cobalt@nickel–cobalt layered double hydroxide nanotube arrays with separated tubes and massive top are designed and fabricated by facile electrodeposition. The as-prepared electrode possesses numerous electroactive sites, a highly conductive Ni/Co metallic core, and a high capacitance NiCo layered double hydroxide shell. The assembled battery-type supercapacitor exhibits superior gravimetric capacitance, good rate performance, high specific energy, and high power density.
      PubDate: 2017-01-11T05:35:39.473902-05:
      DOI: 10.1002/adfm.201605307
       
  • Elasticity, Flexibility, and Ideal Strength of Borophenes
    • Authors: Zhuhua Zhang; Yang Yang, Evgeni S. Penev, Boris I. Yakobson
      Abstract: The mechanical properties of 2D boron—borophene—are studied by first-principles calculations. The recently synthesized borophene with a 1/6 concentration of hollow hexagons (HH) is shown to have in-plane modulus C up to 210 N m−1 and bending stiffness as low as D = 0.39 eV. Thus, its Foppl–von Karman number per unit area, defined as C/D, reaches 568 nm−2, over twofold higher than graphene's value, establishing the borophene as one of the most flexible materials. Yet, the borophene has a specific modulus of 346 m2 s−2 and ideal strength of 16 N m−1, rivaling those (453 m2 s−2 and 34 N m−1) of graphene. In particular, its structural fluxionality enabled by delocalized multicenter chemical bonding favors structural phase transitions under tension, which result in exceptionally small breaking strains yet highly ductile breaking behavior. These mechanical properties can be further tailored by varying the HH concentration, and the boron sheet without HHs can even be stiffer than graphene against tension. The record high flexibility combined with excellent elasticity in boron sheets can be utilized for designing advanced composites and flexible devices.Borophene is a graphene analog for boron. Here, it is predicted that borophene, albeit being lighter than graphene, combines unprecedented flexibility with excellent in-plane elasticity, rendering it as an atomic membrane that is easiest to bend yet hard to stretch. Moreover, borophene can exceptionally resist considerably high loading even when extremely stretched, due to unique tension-induced structural phase transitions.
      PubDate: 2017-01-11T05:35:28.738727-05:
      DOI: 10.1002/adfm.201605059
       
  • Magneto-Thermal Metrics Can Mirror the Long-Term Intracellular Fate of
           Magneto-Plasmonic Nanohybrids and Reveal the Remarkable Shielding Effect
           of Gold
    • Authors: François Mazuel; Ana Espinosa, Guillaume Radtke, Matthieu Bugnet, Sophie Neveu, Yoann Lalatonne, Gianluigi A. Botton, Ali Abou-Hassan, Claire Wilhelm
      Abstract: Multifunctional nanoparticles such as magneto-plasmonic nanohybrids are rising theranostic agents. However, little is yet known of their fate within the cellular environment. In order to reach an understanding of their biotransformations, reliable metrics for tracking and quantification of such materials properties during their intracellular journey are needed. In this study, their long-term (one month) intracellular fate is followed within stem-cell spheroids used as tissue replicas. A set of magnetic (magnetization) and thermal (magnetic hyperthermia, photothermia) metrics is implemented to provide reliable insightsinto the intracellular status. It shows that biodegradation is modulated by the morphology and thickness of the gold shell. First a massive dissolution of the iron oxide core (nanoflower-like) is observed, starting with dissociation of the multigrain structure. Second, it is demonstrated that an uninterrupted gold shell can preserve the magnetic core and properties (particularly magnetic hyperthermia). In addition to the magnetic and thermal metrics, intracellular high-resolution chemical nanocartography evidences the gradual degradation of the magnetic cores. It also shows different transformation scenarios, from the release of small gold seeds when the magnetic core is dissolved (interesting for long-term elimination) to the protection of the magnetic core (interesting for long-term therapeutic applicability).The structural and functional changes of magneto-plasmonic nanohybrids in the local intracellular environment are investigated. It is found that i) magnetic and thermal metrics can act as macroscopic quantitative fingerprints of the intracellular fate of hybrid magneto-plasmonic nanomaterials and ii) the measured massive biodegradation of the magnetic core can be prevented by fine tuning the inert gold shell.
      PubDate: 2017-01-11T05:31:36.812302-05:
      DOI: 10.1002/adfm.201605997
       
  • Tailored Yolk–Shell Sn@C Nanoboxes for High-Performance Lithium
           Storage
    • Authors: Hongwei Zhang; Xiaodan Huang, Owen Noonan, Liang Zhou, Chengzhong Yu
      Abstract: A yolk–shell Sn@C nanobox composite with controllable structures has been synthesized using a facile approach. The void space is engineered to fit the volume expansion of Sn during cycling. It is demonstrated that the shell thickness of carbon nanobox has substantial influence on both nanostructures and the electrochemical performance. With an optimized shell thickness, a high reversible capacity of 810 mA h g−1 can be maintained after 500 cycles, corresponding to 90% retention of the second discharge capacity. For Sn@C materials with either thinner or thicker carbon shells, significant capacity decay or a decreased specific capacity are observed during cycling. The present study sheds light on the rational design of nanostructured electrode materials with enhanced electrochemical performance for next-generation lithium ion batteries.A novel yolk–shell Sn@C nanobox composite with controllable structures has been synthesized using a facile approach. The generation of metallic Sn together with the void space and the conversion of polymer to carbon are simultaneously completed in one step. Importantly, with an optimized carbon shell thickness, the composite exhibits high specific capacity, good rate performance, and exceptional cycling stability.
      PubDate: 2017-01-11T05:31:25.200996-05:
      DOI: 10.1002/adfm.201606023
       
  • Controlled Electrochemical Deposition of Large-Area MoS2 on Graphene for
           High-Responsivity Photodetectors
    • Authors: Xi Wan; Kun Chen, Zefeng Chen, Fangyan Xie, Xiaoliang Zeng, Weiguang Xie, Jian Chen, Jianbin Xu
      Abstract: Controllable creating of wafer-scale homogeneous vertical or parallel 2D heterostructures with low cost by the van der Waals stacking or covalently bonded stitching of 2D layered materials, such as graphene, hexagonal boron nitride, and transition-metal dichalcogenides, is of great challenge. In this paper, a new green growth strategy for the fabrication of high-quality large-area and low-cost vertical MoS2/graphene heterostructures has been successfully demonstrated via electrochemical deposition in water solution, followed by an annealing process in chemical vapour deposition system for the first time. The vertical MoS2/graphene heterostructures have been systematically investigated by the combined use of Raman spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. This simple, reliable, and environmentally friendly growth strategy on conducting monolayer graphene in a controlled manner opens up a new way for producing low-cost, large-area, and high-quality vertical MoS2/graphene heterostructures, which have promising applications not only in electronics and optoelectronics but also in the fields of catalysis and renewable energy.Centimeter-size and homogeneous vertical MoS2/graphene heterostructures have been successfully fabricated in a controlled manner of thickness (5–150 nm) via environmentally friendly electrochemical deposition of MoS2 on conducting graphene electrodes in the aqueous solution of ammonium tetrathiomolybdate (NH4)2MoS4, followed by a vacuum annealing process in the atmosphere of Ar and H2 without additional sulfur.
      PubDate: 2017-01-11T05:20:50.195027-05:
      DOI: 10.1002/adfm.201603998
       
  • Embedding Perovskite Nanocrystals into a Polymer Matrix for Tunable
           Luminescence Probes in Cell Imaging
    • Authors: Haihua Zhang; Xu Wang, Qing Liao, Zhenzhen Xu, Haiyang Li, Lemin Zheng, Hongbing Fu
      Abstract: Lead halide perovskite nanocrystals (NCs) with bright luminescence and broad spectral tunability are good candidates as smart probes for bioimaging, but suffer from hydrolysis even when exposed to atmosphere moisture. In this paper, a strategy is demonstrated by embedding CsPbX3 (X = Cl, Br, I) NCs into microhemispheres (MHSs) of polystyrene matrix to prepare “water-resistant” NCs@MHSs hybrids as multicolor multiplexed optical coding agents. First, a facile room-temperature solution self-assembly approach to highly luminescent colloidal CsPbX3 NCs is developed by injecting a stock solution of CsX⋅PbX2 in N,N-dimethylformamide into dichloromethane. Polyvinyl pyrrolidone (PVP) is chosen as the capping ligand, which is physically adsorbed and wrapped on the surface of perovskite NCs to form a protective layer. The PVP protective layer not only leads to composition-tunable CsPbX3 NCs with high quantum yields and narrow emission linewidths of 12–34 nm but also acts as an interfacial layer, making perovskite NCs compatible with polystyrene polymers and facilitating the next step to embed CsPbX3 NCs into polymer MHSs. CsPbX3 NCs@MHSs are demonstrated as multicolor luminescence probes in live cells with high stability and nontoxicity. Using ten intensity levels and seven-color NCs@MHSs that show non-overlapping spectra, it will be possible to individually tag about ten million cells.A strategy to overcome the inherent vulnerability of perovskites to water is demonstrated by embedding CsPbX3 nanocrystals (NCs) into microhemispheres (MHSs) of polystyrene matrix to prepare “water-resistant” NCs@MHSs hybrids. NCs@MHSs are demonstrated as multicolor luminescence probes in live cells with high stability and nontoxicity. Using ten intensity levels and seven-color NCs@MHSs, it will be possible to individually tag about ten million cells.
      PubDate: 2017-01-11T05:15:27.067465-05:
      DOI: 10.1002/adfm.201604382
       
  • UV Sensors: Materials and Device Designs for an Epidermal UV Colorimetric
           Dosimeter with Near Field Communication Capabilities (Adv. Funct. Mater.
           2/2017)
    • Authors: Hitoshi Araki; Jeonghyun Kim, Shaoning Zhang, Anthony Banks, Kaitlyn E. Crawford, Xing Sheng, Philipp Gutruf, Yunzhou Shi, Rafal M. Pielak, John A. Rogers
      Abstract: A thin, skin-like, butterfly-shaped system combines colorimetry and wireless communication to capture precise dosimetry data in the UV-A and UV-B regions, and for determination of instantaneous UV exposure levels and skin temperature via a smartphone interface is described by J. A. Rogers and co-workers on page 1604465. Quantitative information follows from automated L*a*b* color space analysis of digital images of the devices.
      PubDate: 2017-01-10T05:31:44.953841-05:
      DOI: 10.1002/adfm.201770013
       
  • Cell Scaffolds: Electrospun Photocrosslinkable Hydrogel Fibrous Scaffolds
           for Rapid In Vivo Vascularized Skin Flap Regeneration (Adv. Funct. Mater.
           2/2017)
    • Authors: Xiaoming Sun; Qi Lang, Hongbo Zhang, Liying Cheng, Ying Zhang, Guoqing Pan, Xin Zhao, Huilin Yang, Yuguang Zhang, Hélder A. Santos, Wenguo Cui
      Abstract: Electrospun hydrogel fibrous scaffolds based on photocrosslinkable gelatin exhibit not only hydrogel properties, but maintain a micro three-dimensional (3D) space structure, as presented by Y. Zhang, H. A. Santos, W. Cui, and co-workers on page 1604617. The structure surpasses conventional hydrogels in promotion of 3D cell growth on and migration into the scaffolds and vascularization, and is good for repairing random skin flaps.
      PubDate: 2017-01-10T05:31:44.544195-05:
      DOI: 10.1002/adfm.201770008
       
  • Flexible Electronics: Nanoparticle Assisted Mechanical Delamination for
           
    • Authors: Silvia Colodrero; Pablo Romero-Gomez, Paola Mantilla-Perez, Jordi Martorell
      Abstract: On page 1602969, S. Coloredo, J. Martorell, and co-workers describe a new methodology to attain high performance free-standing organic photovoltaic cells. As depicted in the cover image, a sacrificial nanoparticle layer incorporated in between the substrate and the rest of the cell architecture is used to grow high efficiency cells detachable from the rigid glass substrate.
      PubDate: 2017-01-10T05:31:44.152748-05:
      DOI: 10.1002/adfm.201770009
       
  • Cooperative Effect of GO and Glucose on PEDOT:PSS for High VOC and
           Hysteresis-Free Solution-Processed Perovskite Solar Cells
    • Authors: A. Giuri; S. Masi, S. Colella, A. Kovtun, S. Dell-Elce, E. Treossi, A. Liscio, C. Esposito Corcione, A. Rizzo, A. Listorti
      PubDate: 2017-01-10T05:31:42.961778-05:
      DOI: 10.1002/adfm.201605816
       
  • Contents: (Adv. Funct. Mater. 2/2017)
    • PubDate: 2017-01-10T05:31:42.494127-05:
      DOI: 10.1002/adfm.201770011
       
  • Bioinspired Microenvironments: Rational Design of High-Mobility
           Semicrystalline Conjugated Polymers with Tunable Charge Polarity: Beyond
           Benzobisthiadiazole-Based Polymers (Adv. Funct. Mater. 2/2017)
    • Authors: Yang Wang; Tsukasa Hasegawa, Hidetoshi Matsumoto, Takehiko Mori, Tsuyoshi Michinobu
      Abstract: High-mobility semiconducting polymers for thin film transistors are reported by T. Michinobu and co-workers on page 1604608. The polymers contain strong electronaccepting thiadiazolobenzotriazole units, highly planar vinylene spacers, heteroatom-substituted aromatic rings, and solubilizing alkyl groups. They show p-type transistor behavior with a remarkably high hole mobility of 3.22 cm2 V−1 s−1 as well as n-type dominant ambipolar behavior.
      PubDate: 2017-01-10T05:31:40.064688-05:
      DOI: 10.1002/adfm.201770012
       
  • Masthead: (Adv. Funct. Mater. 2/2017)
    • PubDate: 2017-01-10T05:31:38.200363-05:
      DOI: 10.1002/adfm.201770010
       
  • Chemical Sensing Systems that Utilize Soft Electronics on Thin Elastomeric
           Substrates with Open Cellular Designs
    • Authors: Yoon Kyeung Lee; Kyung-In Jang, Yinji Ma, Ahyeon Koh, Hang Chen, Han Na Jung, Yerim Kim, Jean Won Kwak, Liang Wang, Yeguang Xue, Yiyuan Yang, Wenlong Tian, Yu Jiang, Yihui Zhang, Xue Feng, Yonggang Huang, John A. Rogers
      Abstract: A collection of materials and device architectures are introduced for thin, stretchable arrays of ion sensors that mount on open cellular substrates to facilitate solution exchange for use in biointegrated electronics. The results include integration strategies and studies of fundamental characteristics in chemical sensing and mechanical response. The latter involves experimental measurements and theoretical simulations that establish important considerations in the design of low modulus, stretchable properties in cellular substrates, and in the realization of advanced capabilities in spatiotemporal mapping of chemicals' gradients. As the chemical composition of extracellular fluids contains valuable information related to biological function, the concepts introduced here have potential utility across a range of skin- and internal-organ-integrated electronics where soft mechanics, fluidic permeability, and advanced chemical sensing capabilities are key requirements.A collection of materials and device architectures are introduced for thin, stretchable arrays of ion sensors that mount on open cellular substrates to facilitate solution exchange for use in biointegrated electronics. As the chemical composition of extracellular fluids contains valuable information related to biological function, the concepts and the integration/design strategies introduced here have potential utility across a range of skin- and other organ-integrated electronics where soft mechanics, fluidic permeability, and advanced chemical sensing capabilities are key requirements.
      PubDate: 2017-01-09T08:32:06.743543-05:
      DOI: 10.1002/adfm.201605476
       
  • Epitaxial Stitching and Stacking Growth of Atomically Thin
           Transition-Metal Dichalcogenides (TMDCs) Heterojunctions
    • Authors: Kun Chen; Xi Wan, Jianbin Xu
      Abstract: In recent years, ultrathin two-dimensional (2D) transition metal dichalcogenides (TMDCs), such as MX2 (M = Mo, W; X = S, Se, etc.) have become the flagship materials after graphene. 2D-MX2 have attracted significant attention due to their novel properties arising from their strict dimensional confinement as well as strong spin–orbit coupling effects, which provides an ideal platform for exploring new fundamental research and realizing technological innovation. The 2D nature and the small lattice mismatch between MX2 make them ideal templates for construction of vertical and lateral heterojunctions at atomic scale by means of CVD epitaxial growth. This feature article aims to introduce current advances in the preparation of vertical or lateral epitaxial heterostructures based on 2D MX2 nanosheets as well as their potential applications in electronics, and optoelectronics. Firstly, various epitaxial CVD strategies for synthesis of vertical or lateral 2D MX2 heterostructures are comprehensively reviewed. Meanwhile, the advantages of these epitaxial methods as well as several applications of 2D MX2 heterostructures, such as photodiodes and photovoltaic devices are highlighted. Then the remaining challenges facing the controllable syntheses and the future perspectives of this promising area are discussed.Two-dimensional transition-metal dichalcogenide (2D TMDCs) heterojunctions offer new and exciting opportunities to fabricate novel devices with unprecedented performance. Currently, the chemical vapor deposition technique (CVD) has displayed great promise to prepare lateral or vertical epitaxial TMDCs heterostructures. An overview of recent progress in the epitaxial growth of heterojunctions on the basis of ultrathin TMDCs and their potential application is presented.
      PubDate: 2017-01-09T08:31:55.550487-05:
      DOI: 10.1002/adfm.201603884
       
  • Enzymatic Biodegradability of Pristine and Functionalized Transition Metal
           Dichalcogenide MoS2 Nanosheets
    • Authors: Rajendra Kurapati; Laura Muzi, Aritz Perez Ruiz de Garibay, Julie Russier, Damien Voiry, Isabella A. Vacchi, Manish Chhowalla, Alberto Bianco
      Abstract: 2D transition metal dichalcogenide MoS2 nanosheets are increasingly attracting interests due to their promising applications in materials science and biomedicine. However, their biocompatibility and their biodegradability have not been thoroughly studied yet. Here, the biodegradability of exfoliated pristine and covalently functionalized MoS2 (f-MoS2) is investigated. First, biodegradability of these nanomaterials is evaluated using plant horseradish peroxidase and human myeloperoxidase. The results reveal that the enzymatic degradability rate of MoS2 and f-MoS2 is slower than in the case of the simple treatment with H2O2 alone. In parallel, high biocompatibility of both pristine and f-MoS2 nanosheets is found up to 100 µg mL−1 in both cell lines (HeLa and Raw264.7) and primary immune cells. In addition, no immune cell activation and minimal pro-inflammatory cytokine release are observed in RAW264.7 and human monocyte-derived macrophages, suggesting a negligible cellular impact of such materials. Furthermore, the effects of degraded MoS2 and partially degraded f-MoS2 products on cell viability and activation are studied in cancer and immune cells. A certain cytotoxicity is measured at the highest concentrations. Finally, to prove that the cellular impact is due to cell uptake, the internalization of both pristine and functionalized MoS2 in cancer and primary immune cells is assessed.Biodegradation of pristine and covalently functionalized MoS2 by peroxidases in the presence of H2O2 is reported. A faster degradation compared to peroxidase treatment is observed without enzymes using biologically relevant concentrations of H2O2. Importantly, covalent functionalization of MoS2 alters the degradation profile of this type of nanomaterials, opening interesting perspectives in the design of new biomedical tools.
      PubDate: 2017-01-09T08:31:32.641106-05:
      DOI: 10.1002/adfm.201605176
       
  • Cobalt Assisted Synthesis of IrCu Hollow Octahedral Nanocages as Highly
           Active Electrocatalysts toward Oxygen Evolution Reaction
    • Authors: Taehyun Kwon; Hyeyoun Hwang, Young Jin Sa, Jongsik Park, Hionsuck Baik, Sang Hoon Joo, Kwangyeol Lee
      Abstract: Development of oxygen evolution reaction (OER) catalysts with reduced precious metal content while enhancing catalytic performance has been of pivotal importance in cost-effective design of acid polymer electrolyte membrane water electrolyzers. Hollow multimetallic nanostructures with well-defined facets are ideally suited for saving the usage of expensive precious metals as well as boosting catalytic performances; however, Ir-based hollow nanocatalysts have rarely been reported. Here, a very simple synthetic scheme is reported for the preparation of hollow octahedral nanocages of Co-doped IrCu alloy with readily tunable morphology and size. The Co-doped IrCu octahedral nanocages show excellent electrocatalytic activity and long-term durability for OER in acidic media. Notably, their OER activity represents one of the best performances among Ir-based acidic OER catalysts.Novel facet-controlled Co-doped IrCu octahedral hollow nanocages exhibit excellent electrocatalytic activity and durability toward the oxygen evolution reaction in acidic conditions.
      PubDate: 2017-01-09T08:30:55.350544-05:
      DOI: 10.1002/adfm.201604688
       
  • Toward Sensitive Room-Temperature Broadband Detection from Infrared to
           Terahertz with Antenna-Integrated Black Phosphorus Photoconductor
    • Authors: Lin Wang; Changlong Liu, Xiaoshuang Chen, Jing Zhou, Weida Hu, Xiaofang Wang, Jinhua Li, Weiwei Tang, Anqi Yu, Shao-Wei Wang, Wei Lu
      Abstract: Graphene-like two-dimensional materials (graphene, transition-metal dichalcogenides (TMDCs)) have received extraordinary attention owing to their rich physics and potential applications in building nanoelectronic and nanophotonic devices. Recent works have concentrated on increasing the responsivity and extending the operation range to longer wavelengths. However, the weak absorption of gapless graphene, and the large bandgap (>1 eV) and low mobility in TMDCs have limited their spectral usage to only a narrow range in the visible spectrum. In this work, we demonstrate for the first time a high-performance, antenna-integrated, black phosphorus (BP)-based photoconductor with ultra-broadband detection from the infrared to terahertz frequencies. The good trade-off between the moderate bandgap and good mobility results in a broad spectral absorption that is superior to that of graphene. Different photoconductive mechanisms, such as photothermoelectric (PTE), bolometric, and electron–hole generation can be distinguished depending on the device geometry, incident wavelength, and power. Especially, the photoconductive response remains highly efficient, even when the photon energy is extended to the terahertz (THz) band at room temperature, which is driven by the thermoelectric-induced well. The proposed photodetectors have a superior performance with an excellent sensitivity of over 300 V W−1, low noise equivalent power (NEP) (smaller than 1 nW Hz−0.5 (10 pW Hz−0.5) with respect to the incident (absorbed) power), and fast response, all of which play key roles in multispectral biological imaging, remote sensing, and optical communications.A highly efficient room-temperature black phosphorus (BP) detector is shown that can operate from the infrared to the terahertz bands. The moderate bandgap and high mobility of black phosphorus make it a good candidate for both infrared and terahertz detections. Different detection principles are reported for the antenna-coupled BP detector, which is based on the photoconductive effect transiting from the interband electron–hole relaxations to intraband wave excitations.
      PubDate: 2017-01-09T08:30:50.07365-05:0
      DOI: 10.1002/adfm.201604414
       
  • Two-Step Sequential Deposition of Organometal Halide Perovskite for
           Photovoltaic Application
    • Authors: Haining Chen
      Abstract: Organometal halide perovskite materials have become a superstar in the photovoltaic (PV) field because of their advantageous properties, which boost the power conversion efficiency (PCE) of perovskite solar cells (PSCs) from about 3.8% to above 22% in just seven years. Most importantly, such promising achievement is mainly based on its low-cost and solution-processed fabrication technique. One of the most promising and famous approaches to fabricating perovskite is a two-step sequential deposition method because precursor (e.g., PbI2) deposition is controllable, versatile, and flexible. Due to tremendous efforts, great progress has been achieved on the two-step sequential deposition method, which helps to promote the development of PSCs. Herein, the progresses on the two-step sequential deposition method of perovskite layers is reviewed thoroughly. At first, the reaction process and principle is introduced and discussed. Then, the research on the deposition techniques, structures, and compositions of precursors (the first step) is presented. Subsequently, the developments on the conversion techniques, conversion solutions, and growth of large crystals at the second step are introduced. Finally, four important issues on the two-step sequential deposition method will be stated, accompanied with proposed solutions.The two-step sequential deposition method is one of the most important deposition methods for the organometal halide perovskite layer in photovoltaic application. So far, great progress has been made on this method, which helps to promote the development of PSCs. Herein, its recent achievements are reviewed and the important issues are highlighted while proposing the corresponding solutions.
      PubDate: 2017-01-06T08:31:27.97636-05:0
      DOI: 10.1002/adfm.201605654
       
  • Corrosion-Resistant Superhydrophobic Coatings on Mg Alloy Surfaces
           Inspired by Lotus Seedpod
    • Authors: Dongmian Zang; Ruiwen Zhu, Wen Zhang, Xinquan Yu, Ling Lin, Xinglin Guo, Mingjie Liu, Lei Jiang
      Abstract: Superhydrophobic surfaces are widely found in nature, inspiring the development of excellent antiwater surfaces with barrier coatings isolating the underlying materials from the external environment. Here, the naturally occurring superhydrophobicity of lotus seedpod surfaces is reported. Protective coatings that mimic the lotus seedpod are fabricated on AZ91D Mg alloy surfaces with the synergistic effect of robust superhydrophobicity and durable corrosion resistance. The predesigned titanium dioxide films are coated on AZ91D by an in situ hydrothermal synthesis technique. Through sonication assisted electroless plating combined with a self-assembling method, the densely packed Cu-thiolate layers are uniformly plated with robust adhesion on the Mg alloy substrate, which function as a superhydrophobic barrier that can hold back the transport of water and corrosive ions contained such as Cl−. Notably, the two extreme wetting behaviors (superhydrophilicity and superhydrophobicity) as well as corrosion resistance and improved corrosion resistance can be easily controlled by removal of the hydrophobic materials (n-dodecanethiol) at elevated temperature (350 °C) and modifying them at room temperature for 18 cycles, indicative of exceptional adhesion between the superhydrophobic coating and the underlying AZ91D Mg alloy.Inspired by the lotus seedpod, a strategy to fabricate self-assembled monolayers on AZ91D Mg alloys with exceptional superhydrophobic and corrosion-resistant surfaces is reported. The surfaces exhibit a thermally controlled wetting transition between the superhydrophilic and super­hydrophobic states, and corrosion behavior ranging from corrosion resistance to improved corrosion resistance. This strategy will lead to improved corrosion-resistant Mg alloys and thermally responsive “surface engineering.”
      PubDate: 2017-01-06T08:31:13.653604-05:
      DOI: 10.1002/adfm.201605446
       
  • Thermal Properties of Two Dimensional Layered Materials
    • Authors: Yuxi Wang; Ning Xu, Deyu Li, Jia Zhu
      Abstract: The rise of graphene has motivated intensive investigation into other two-dimensional layered materials (2DLMs). In addition to their superior optical, electrical, and mechanical properties, 2DLMs have also demonstrated intriguing thermal properties, the understanding of which is not only fundamentally important but also critical to enabling widespread applications in electronics, optoelectronics, and energy conversion and storage devices. Here, we review recent progress in the thermal transport of 2DLMs. Indeed, due to unique and diversified two dimensional crystal structures and the contribution of different phonon modes to thermal transport, while the family of 2DLMs share common thermal properties, such as layer-dependent thermal conductivity, each member also has unique features related to thermal transport. Ultimately, the unusual and rich thermal properties of two-dimensional materials can lay a solid foundation for understanding new phonon transport physics and potentially lead to novel applications in various emerging fields.Two dimensional layered materials (2DLMs) have shown unique thermal transport properties, such as anomalous size-dependent and anisotropic thermal conductivity. The recent progress in thermal property measurement (measurement methods and measurement results) for 2DLMs is reviewed and their potential applications in energy conversion and thermal management are also discussed.
      PubDate: 2017-01-06T08:31:00.147035-05:
      DOI: 10.1002/adfm.201604134
       
  • Self-Assembly of Semiconducting Polymer Amphiphiles for In Vivo
           Photoacoustic Imaging
    • Authors: Chen Xie; Xu Zhen, Qunli Lei, Ran Ni, Kanyi Pu
      Abstract: Despite the advantages of semiconducting polymer nanoparticles (SPNs) over other inorganic nanoparticles for photoacoustic (PA) imaging, their synthetic method is generally limited to nanoprecipitation, which is likely to cause the issue of nanoparticle dissociation. The synthesis of near-infrared (NIR) absorbing semiconducting polymer amphiphiles (SPAs) that can spontaneously self-assemble into homogeneous nanoparticles for in vivo PA imaging is reported. As compared with their counterpart nanoparticles (SPN1) prepared through nanoprecipitation, SPAs generally have higher fluorescence quantum yields but similar size and PA brightness, making them superior over SPN1. Optical and simulation studies reveal that the poly(ethylene glycol) (PEG) grafting density plays a critical role in determining the packing of SP segments inside the core of nanoparticles, consequently affecting the optical properties. The small size and structurally stable nanostructure, in conjunction with a dense PEG shell, allow SPAs to passively target tumors of living mice after systemic administration, permitting both PA and fluorescence imaging of the tumors at signals that are ≈1.5-fold higher than that of liver. This study thus not only provides the first generation of amphiphilic optically active polymers for PA imaging, but also highlights the molecular guidelines for the development of organic NIR imaging nanomaterials.Near-infrared absorbing semiconducting polymer amphiphiles (SPAs) that can spontaneously self-assemble into homogenous nanoparticles are synthesized. The small size and structurally stable nanostructure in conjunction with a dense poly(ethylene glycol) shell allow SPAs to passively target tumors of living mice after systemic administration, permitting both photoacoustic and fluorescence imaging of the tumors.
      PubDate: 2017-01-06T08:30:40.730249-05:
      DOI: 10.1002/adfm.201605397
       
  • Photoinduced Tetrazole-Based Functionalization of Off-Stoichiometric
           Clickable Microparticles
    • Authors: Chen Wang; Markus M. Zieger, Alexander Schenzel, Martin Wegener, Johannes Willenbacher, Christopher Barner-Kowollik, Christopher N. Bowman
      Abstract: We report the preparation of tetrazole-containing step-growth microparticles and the subsequent use of photoinduced nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) reactions on the particles with spatiotemporal control. Microparticles with an average diameter of 4.1 µm and with inherent tetrazole-ene dual functionality are prepared by a one-pot off-stoichiometric thiol-Michael addition dispersion polymerization. The NITEC reaction is performed efficiently in the solid phase by UV irradiation, leading to the formation of fluorescent pyrozoline adducts, with an estimated quantum yield of 0.7. Particle concentration-independent reaction kinetics are observed and full conversion is reached within 10 min of UV exposure at an intensity of 8 mW cm−2. Temporal control is demonstrated with either UV or rooftop sunlight irradiation of variable duration. By using two-photon writing with a laser centered around 700 nm wavelength, spatial control is demonstrated with micrometer-scale resolution via surface patterning of the microparticles. Further, microparticles with exclusive tetrazole functionality are prepared by a one-pot, two-step thiol-Michael addition dispersion polymerization. The NITEC reaction between tetrazole-functional particles and acrylates in solution is examined at various tetrazole/alkene molar ratios, and a 10:1 excess of alkenes in solution is found necessary for efficient functionalization.We report the preparation of tetrazole-containing step-growth microparticles and the subsequent use of photoinduced nitrile imine-mediated tetrazole-ene cycloaddition reactions on the particles with spatiotemporal control.
      PubDate: 2017-01-06T08:30:34.083959-05:
      DOI: 10.1002/adfm.201605317
       
  • Kirigami/Origami-Based Soft Deployable Reflector for Optical Beam Steering
    • Authors: Wei Wang; Chenzhe Li, Hugo Rodrigue, Fengpei Yuan, Min-Woo Han, Maenghyo Cho, Sung-Hoon Ahn
      Abstract: The beam steering mechanism has been a key element for various applications ranging from sensing and imaging to solar tracking systems. However, conventional beam steering systems are bulky and complex and present significant challenges for scaling up. This work introduces the use of soft deployable reflectors combining a soft deployable structure with simple kirigami/origami reflective films. This structure can be used as a macroscale beam steering mechanism that is both simple and compact. This work first develops a soft deployable structure that is easily scalable by patterning of soft linear actuators. This soft deployable structure is capable of increasing its height several folds by expanding in a continuous and controllable manner, which can be used as a frame to deform the linearly stretchable kirigami/origami structures integrated into the structure. Experiments on the reflective capability of the reflectors are conducted and show a good fit to the modeling results. The proposed principles for deployment and for beam steering can be used to realize novel active beam steering devices, highlighting the use of soft robotic principles to produce scalable morphing structures.Soft deployable reflectors combining a soft deployable structure with simple kirigami/origami reflective films used for dynamic beam steering are presented in this work. This structure can self-deploy by expanding its height several folds. Origami/kirigami reflectors, essentially mirrors with slits, are placed in hollow pockets of the soft deployable structure whose large deformation changes the reflection angle of the reflectors.
      PubDate: 2017-01-05T04:26:12.443096-05:
      DOI: 10.1002/adfm.201604214
       
  • Layer-Number Dependent Optical Properties of 2D Materials and Their
           Application for Thickness Determination
    • Authors: Xiao-Li Li; Wen-Peng Han, Jiang-Bin Wu, Xiao-Fen Qiao, Jun Zhang, Ping-Heng Tan
      Abstract: The quantum confinement in atomic scale and the presence of interlayer coupling in multilayer make the electronic and optical properties of 2D materials (2DMs) be dependent on the layer number (N) from monolayer to multilayer. Optical properties of 2DMs have been widely probed by several optical techniques, such as optical contrast, Rayleigh scattering, Raman spectroscopy, optical absorption, photoluminescence, and second harmonic generation. Here, it is reviewed how optical properties of several typical 2DMs (e.g., monolayer and multilayer graphenes, transition metal dichalcogenides) probed by these optical techniques significantly depend on N. Further, it has been demonstrated how these optical techniques service as fast and nondestructive approaches for N counting or thickness determination of these typical 2DM flakes. The corresponding approaches can be extended to the whole 2DM family produced by micromechanical exfoliations, chemical-vapor-deposition growth, or transfer processes on various substrates, which bridges the gap between the characterization and international standardization for thickness determination of 2DM flakes.Optical properties of 2D materials, such as optical contrast, Rayleigh scattering, Raman spectroscopy, optical absorption, photoluminescence, and second harmonic generation, are dependent on the layer number. Here, we demonstrate how these optical techniques serve as fast and nondestructive approaches for layer number counting or thickness determination of these typical 2D material flakes.
      PubDate: 2017-01-05T04:26:00.735409-05:
      DOI: 10.1002/adfm.201604468
       
  • Long Minority-Carrier Diffusion Length and Low Surface-Recombination
           
    • Authors: Bo Wu; Yuanyuan Zhou, Guichuan Xing, Qiang Xu, Hector F. Garces, Ankur Solanki, Teck Wee Goh, Nitin P. Padture, Tze Chien Sum
      Abstract: Sn-based perovskites are promising Pb-free photovoltaic materials with an ideal 1.3 eV bandgap. However, to date, Sn-based thin film perovskite solar cells have yielded relatively low power conversion efficiencies (PCEs). This is traced to their poor photophysical properties (i.e., short diffusion lengths (
      PubDate: 2017-01-05T04:25:39.889513-05:
      DOI: 10.1002/adfm.201604818
       
  • Interface Engineered WxC@WS2 Nanostructure for Enhanced Hydrogen Evolution
           Catalysis
    • Authors: Fengmei Wang; Peng He, Yuanchang Li, Tofik Ahmed Shifa, Ya Deng, Kaili Liu, Qisheng Wang, Feng Wang, Yao Wen, Zhenxing Wang, Xueying Zhan, Lianfeng Sun, Jun He
      Abstract: For increasing scalability and reducing cost, transition metal dichalcogenides-based electrocatalysts presently have been proposed as substitutes for noble metals to generate hydrogen, but these alternatives usually suffer from inferior performance. Here, a Ravenala leaf-like WxC@WS2 heterostructure is grown via carbonizing WS2 nanotubes, whose outer walls being partially unzipped along with the Wx C “leaf-valves” attached to the inner tubes during the carbonization process. This heterostructure exhibits a catalytic activity for hydrogen evolution reaction with low overpotential of 146 mV at 10 mA cm−2 and Tafel slope of 61 mV per decade, outperforming the performance of WS2 nanotubes and WxC counterparts under the same condition. Density functional theory calculations are performed to unravel the underlying mechanism, revealing that the charge distribution between WxC and WS2 plays a key role for promoting H atom adsorption and desorption kinetics simultaneously. This work not only provides a potential low-cost alternative for hydrogen generation but should be taken as a guide to optimize the catalyst structure and composition.Here, a Ravenala leaf-like WxC@WS2 heterostructure with WxC “leaf-valves” attached to the inner WS2 tubes is grown. Its catalytic activity for hydrogen evolution reaction outperforms that of WS2 and WxC counterparts under the same condition. Theoretical calculations reveal the charge distribution at the interface between WxC and WS2 plays a key role for promoting H atom adsorption and desorption kinetics simultaneously.
      PubDate: 2017-01-05T04:25:32.951465-05:
      DOI: 10.1002/adfm.201605802
       
  • Conjugation-Induced Thermally Activated Delayed Fluorescence (TADF): From
           Conventional Non-TADF Units to TADF-Active Polymers
    • Authors: Qiang Wei; Paul Kleine, Yevhen Karpov, Xianping Qiu, Hartmut Komber, Karin Sahre, Anton Kiriy, Ramunas Lygaitis, Simone Lenk, Sebastian Reineke, Brigitte Voit
      Abstract: Thermally activated delayed fluorescence (TADF)-type compounds have great potential as emitter molecules in organic light-emitting diodes, allowing for electrofluorescence with 100% internal quantum efficiency. In small molecules, TADF is achieved through the formation of intramolecular charge-transfer states. The only design limitation is the requirement that donor and acceptor entities spatially decouple the highest occupied and lowest unoccupied molecular orbitals, respectively, to minimize exchange splitting. The development of polymeric TADF emitters, on the contrary, has seen comparably small progress and those are typically built up from monomeric units that show promising TADF properties in small molecule studies beforehand. By contrast, herein, a way to achieve TADF properties in cyclic oligomers and polymers composed of non-TADF building blocks is shown. Due to a strongly decreased energy splitting of the polymer with respect to the individual repeating unit between the lowest singlet and triplet excited state (ΔEST) and a sufficiently high radiative decay rate kSr, a highly efficient TADF polymer with up to 71% photoluminescence quantum yield is obtained. For the first time, an encouraging method is provided for producing highly efficient TADF oligomers and polymers from solely non-TADF units via induced conjugation, opening a new design strategy exclusive for polymers.A thermally activated delayed fluorescence (TADF) π-conjugated cyclic polymer composed of non-TADF building blocks is developed. Conjugation-induced highest occupied molecular orbital destabilization leads to a decreased singlet–triplet splitting and efficient TADF in the polymer, while the repeating unit itself shows only inefficient phosphorescence. This conjugation-induced TADF concept represents a novel molecular design rule particularly for solution-processable polymeric materials.
      PubDate: 2017-01-04T08:55:44.698321-05:
      DOI: 10.1002/adfm.201605051
       
  • Phase Transition Induced Synthesis of Layered/Spinel Heterostructure with
           Enhanced Electrochemical Properties
    • Authors: Yi Pei; Cheng-Yan Xu, Yu-Chen Xiao, Qing Chen, Bin Huang, Bin Li, Shuang Li, Liang Zhen, Guozhong Cao
      Abstract: A one-step synthesis of Li-rich layered materials with layered/spinel heterostructure has been systematically investigated. The composites are synthesized by a polyol method followed with an annealing process at 500–900 °C for 12 h. A spinel to layer phase transition is considered to take place during the heat treatment, and the samples obtained at different temperatures show diverse phase compositions. An “Li-rich spinel phase decomposition” phase transition mechanism is proposed to explain the formation of such a heterostructure. The electrochemical properties of the heterostructure are found to be associated with the ratio of spinel to layer phases, the leach out of rock salt phase, and the change of crystallinity and particle size. Product with improved cyclic and rate performance is achieved by annealing at 700 °C for 12 h, with a discharge capacity of 214 mA h g−1 remaining at 0.2 C after 60 cycles and discharge capacity of about 200 mA h g−1 at 1 C.Li-rich layered materials with layered/spinel heterostructure are prepared through a novel polyol method. With an “Li-rich spinel phase decomposition” phase transition mechanism, the content of LLO is controllable and the products with moderate content of spinel phase demonstrate superior electrochemical performances with a discharge capacity of about 200 mA h g−1 at 1 C.
      PubDate: 2017-01-04T08:55:31.055397-05:
      DOI: 10.1002/adfm.201604349
       
  • Al-Doped Black Phosphorus p–n Homojunction Diode for High
           Performance Photovoltaic
    • Authors: Yuanda Liu; Yongqing Cai, Gang Zhang, Yong-Wei Zhang, Kah-Wee Ang
      Abstract: 2D layered materials based p–n junctions are fundamental building block for enabling new functional device applications with high efficiency. However, due to the lack of controllable doping technique, state-of-the-art 2D p–n junctions are predominantly made of van der Waals heterostructures or electrostatic gated junctions. Here, the authors report the demonstration of a spatially controlled aluminum doping technique that enables a p–n homojunction diode to be realized within a single 2D black phosphorus nanosheet for high performance photovoltaic application. The diode achieves a near-unity ideality factor of 1.001 along with an on/off ratio of ≈5.6 × 103 at a low bias of 2 V, allowing for low-power dynamic current rectification without signal decay or overshoot. When operated under a photovoltaic regime, the diode's dark current can be significantly suppressed. The presence of a built-in electric field additionally gives rise to temporal short-circuit current and open-circuit voltage under zero external bias, indicative of its enriched functionalities for self-powered photovoltaic and high signal-to-noise photodetection applications.2D p–n junction is a fundamental building block for nanoelectronics devices, which has been predominantly realized using van der Waals heterostructures or electrostatic-gated junctions due to the lack of controllable doping techniques. Here, near-ideal black phosphorus p–n homojunction diodes are achieved by novel and facile Al-atom doping, paving the way toward high performance photovoltaic applications.
      PubDate: 2017-01-03T09:15:56.104535-05:
      DOI: 10.1002/adfm.201604638
       
  • Analyzing the Carrier Mobility in Transition-Metal Dichalcogenide MoS2
           Field-Effect Transistors
    • Authors: Zhihao Yu; Zhun-Yong Ong, Songlin Li, Jian-Bin Xu, Gang Zhang, Yong-Wei Zhang, Yi Shi, Xinran Wang
      Abstract: Transition-metal dichalcogenides (TMDCs) are an important class of two-dimensional (2D) layered materials for electronic and optoelectronic applications, due to their ultimate body thickness, sizable and tunable bandgap, and decent theoretical room-temperature mobility. So far, however, all TMDCs show much lower mobility experimentally because of the collective effects by foreign impurities, which has become one of the most important limitations for their device applications. Here, taking MoS2 as an example, the key factors that bring down the mobility in TMDC transistors, including phonons, charged impurities, defects, and charge traps, are reviewed. A theoretical model that quantitatively captures the scaling of mobility with temperature, carrier density, and thickness is introduced. By fitting the available mobility data from literature over the past few years, one obtains the density of impurities and traps for a wide range of transistor structures. It shows that interface engineering can effectively reduce the impurities, leading to improved device performances. For few-layer TMDCs, the lopsided carrier distribution is analytically modeled to elucidate the experimental increase of mobility with the number of layers. From our analysis, it is clear that the charge transport in TMDC samples is a very complex problem that must be handled carefully.Transition-metal dichalcogenides (TMDCs) are widely investigated for enhanced characteristics for electronics among next generation semiconductors. The understanding of charge transport in TMDCs is significant for further device applications. Through carefully analyzing the reported high performance MoS2 devices, this review provides a systematic theoretical and experimental path to optimize the device structure and improve device performance.
      PubDate: 2017-01-03T09:15:51.577192-05:
      DOI: 10.1002/adfm.201604093
       
  • Atomic Insights into the Enhanced Surface Stability in High Voltage
           Cathode Materials by Ultrathin Coating
    • Authors: Xin Fang; Feng Lin, Dennis Nordlund, Matthew Mecklenburg, Mingyuan Ge, Jiepeng Rong, Anyi Zhang, Chenfei Shen, Yihang Liu, Yu Cao, Marca M. Doeff, Chongwu Zhou
      Abstract: Surface properties of electrode materials play a critical role in the function of batteries. Therefore, surface modifications, such as coatings, have been widely used to improve battery performance. Understanding how these coatings function to improve battery performance is crucial for both scientific research and applications. In this study the electrochemical performance of coated and uncoated LiNi0.5Mn1.5O4 (LNMO) electrodes is correlated with ensemble-averaged soft X-ray absorption spectroscopy (XAS) and spatially resolved scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) to illustrate the mechanism of how ultrathin layer Al2O3 coatings improve the cycle life of LiNi0.5Mn1.5O4. Mn2+ evolution on the surface is clearly observed in the uncoated sample, which results from the reaction between the electrolytic solution and the surfaces of LiNi0.5Mn1.5O4 particles, and also possibly atomic structure reconstructions and oxygen loss from the surface region in LiNi0.5Mn1.5O4. The coating effectively suppresses Mn2+ evolution and improves the battery performance by decelerating the impedance buildup from the surface passivation. This study demonstrates the importance of combining ensemble-averaged techniques (e.g., XAS) with localized techniques (e.g., STEM-EELS), as the latter may yield unrepresentative information due to the limited number of studied particles, and sheds light on the design of future coating processes and materials.Atomic layer deposition was employed as an ultrathin coating on LiNi0.5Mn1.5O4, a cathode in lithium-ion batteries. X-ray absorption spectroscopy and scanning transmission electron microscopy-electron energy loss spectroscopy were used to characterize both pristine and coated materials before and after cycling. The results show that the coating suppressed Mn2+ formation, decelarating impedance buildup from surface passivation and improving cycling behavior.
      PubDate: 2017-01-03T09:15:35.010825-05:
      DOI: 10.1002/adfm.201602873
       
  • Toroidal Protein Adaptor Assembles Ferrimagnetic Nanoparticle Fibers with
           Constructive Magnetic Coupling
    • Authors: Tuan Anh Pham; Andreas Schreiber, Stefan M. Schiller, Helmut Cölfen
      Abstract: Inspired by nature, the synthesis of biohybrid nanocomposites containing inorganic nanoparticles (NPs) and biopolymers such as DNA and peptides as templates offers great potential for a wide range of applications. Using selective recognition schemes of 3D protein spaces for the assembly of magnetic nanocrystals is a challenge with great promise in the field of biomedicine and magnetic data storage. Here we apply the toroidal protein Hcp1 as an interparticle connector for the directed molecular assembly and ferrimagnetic coupling of biohybrid cobalt ferrite NP wires. The resulting biohybrid NP composites show bundles of nanofibers ranging from nano- to the microscale in length verified by TEM, EDX analysis and focused ion beam cut. Their magnetic characterization reveals an increase of the coercive field (+12%) reaching values of high-end Nd2Fe14B bulk magnets, enhanced saturation (+28%) and remanence magnetization (+38%) at 2 K compared to NPs lacking the protein connector. Thus, the combination of the nanoscale alignment of magnetic NPs with the molecular precision of the protein connectors leads to constructive addition of the magnetization reversal energy. This approach can be used to control magnetic properties for the design of materials with enhanced coercivity applicable for magnetic data storage, hyperthermia and theranostics.Applying the toroidal protein Hcp1 as an interparticle connector leads to directed molecular assembly and ferrimagnetic coupling of cobalt ferrite nanoparticles. Assembled biohybrid nanofibers range from the nano- to the microscale. Their magnetic characterization reveals enhanced saturation (+28%) and remanence magnetization (+38%) and an increase in the coercive field (+12%) reaching values of high-end Nd2Fe14B bulk magnets at 2 K.
      PubDate: 2017-01-03T01:52:23.7521-05:00
      DOI: 10.1002/adfm.201604532
       
  • Electrowetting-Induced Morphological Evolution of Metal-Organic Inverse
           Opals toward a Water-Lithography Approach
    • Authors: Junchao Liu; Lun Wan, Manbo Zhang, Kejian Jiang, Kai Song, Jingxia Wang, Tomiki Ikeda, Lei Jiang
      Abstract: This paper presents a unique morphological evolution of metal-organic inverse opals (Pb(NO3)2-poly(St-MMA-AA)) subjected to an electrowetting process. The morphology of the building blocks changes from interconnected pores to separated hollow spheres during the electrowetting process, accompanied by an unusual blue-shift of the stopband position and the decreased wettability of the film. This morphology evolution is attributed to the simultaneous collapse/reconstruction of the metal-organic frame owing to the partial dissolution of the metal salt and the interfacial assembly of the metal-organic coordination around the skeleton. The adjustable morphology can be developed as a novel and simple water-lithography approach for the creation of the photonic crystal pattern.A unique morphological evolution is demonstrated for metal-organic inverse opals during an electrowetting process. The building blocks of inverse opals change from the interconnected pore to the separated hollow sphere with respect to electrowetting time, accompanied by a blue-shift in the reflection bands and the decreased wettability of the film, which provides a facile strategy for the water-lithography technique.
      PubDate: 2017-01-03T01:52:10.118142-05:
      DOI: 10.1002/adfm.201605221
       
  • Facile Doping and Work-Function Modification of Few-Layer Graphene Using
           Molecular Oxidants and Reductants
    • Authors: Ahmed E. Mansour; Marcel M. Said, Sukumar Dey, Hanlin Hu, Siyuan Zhang, Rahim Munir, Yadong Zhang, Karttikay Moudgil, Stephen Barlow, Seth R. Marder, Aram Amassian
      Abstract: Doping of graphene is a viable route toward enhancing its electrical conductivity and modulating its work function for a wide range of technological applications. In this work, the authors demonstrate facile, solution-based, noncovalent surface doping of few-layer graphene (FLG) using a series of molecular metal-organic and organic species of varying n- and p-type doping strengths. In doing so, the authors tune the electronic, optical, and transport properties of FLG. The authors modulate the work function of graphene over a range of 2.4 eV (from 2.9 to 5.3 eV)—unprecedented for solution-based doping—via surface electron transfer. A substantial improvement of the conductivity of FLG is attributed to increasing carrier density, slightly offset by a minor reduction of mobility via Coulomb scattering. The mobility of single layer graphene has been reported to decrease significantly more via similar surface doping than FLG, which has the ability to screen buried layers. The dopant dosage influences the properties of FLG and reveals an optimal window of dopant coverage for the best transport properties, wherein dopant molecules aggregate into small and isolated clusters on the surface of FLG. This study shows how soluble molecular dopants can easily and effectively tune the work function and improve the optoelectronic properties of graphene.Solution-based noncovalent doping of few-layer graphene using novel metal-organic and organic molecules is demonstrated to enhance the conductivity and modulate the work function over a range of 2.4 eV with marginal reduction of mobility. The effects of dopant strength and coverage are shown to play a crucial role in the optimization of the performance of few-layer graphene as a transparent conductive electrode.
      PubDate: 2017-01-03T01:52:05.038416-05:
      DOI: 10.1002/adfm.201602004
       
  • Multifunctional Materials: A Case Study of the Effects of Metal Doping on
           ZnO Tetrapods with Bismuth and Tin Oxides
    • Authors: Vasile Postica; Jorit Gröttrup, Rainer Adelung, Oleg Lupan, Abhishek Kumar Mishra, Nora H. de Leeuw, Nicolai Ababii, José F. C. Carreira, Joana Rodrigues, Nebiha Ben Sedrine, Maria Rosário Correia, Teresa Monteiro, Victor Sontea, Yogendra Kumar Mishra
      Abstract: Hybrid metal oxide nano- and microstructures exhibit novel properties, which make them promising candidates for a wide range of applications, including gas sensing. In this work, the characteristics of the hybrid ZnO-Bi2O3 and ZnO-Zn2SnO4 tetrapod (T) networks are investigated in detail. The gas sensing studies reveal improved performance of the hybrid networks compared to pure ZnO-T networks. For the ZnO-T-Bi2O3 networks, an enhancement in H2 gas response is obtained, although the observed p-type sensing behavior is attributed to the formed junctions between the arms of ZnO-T covered with Bi2O3 and the modulation of the regions where holes accumulate under exposure to H2 gas. In ZnO-T-Zn2SnO4 networks, a change in selectivity to CO gas with high response is noted. The devices based on individual ZnO-T-Bi2O3 and ZnO-T-Zn2SnO4 structures showed an enhanced H2 gas response, which is explained on the basis of interactions (electronic sensitization) between the ZnO-T arm and Bi2O3 shell layer and single Schottky contact structure, respectively. Density functional theory-based calculations provide mechanistic insights into the interaction of H2 and CO gas molecules with Bi- and Sn-doped ZnO(0001) surfaces, revealing changes in the Fermi energies, as well as charge transfer between the molecules and surface species, which facilitate gas sensing.Gas sensing and optical properties of hybrid 3D ZnO-T (tetrapods) with Bi2O3 and Zn2SnO4 networks are reported. The investigations reveal improved gas sensing performances of hybrid networks compared with pure ZnO-T (tetrapod) networks. The described synthesis strategy serves as an excellent method to fabricate enhanced and selective gas sensors. ZnO-T-Bi2O3 hybrids enhance H2 gas response whereas ZnO-T-Zn2SnO4 changes selectivity to CO.
      PubDate: 2016-12-30T06:01:13.064057-05:
      DOI: 10.1002/adfm.201604676
       
  • Stabilized Octahedral Frameworks in Layered Double Hydroxides by
           Solid-Solution Mixing of Transition Metals
    • Authors: Ji Hoon Lee; Hyeon Jeong Lee, Soo Yeon Lim, Keun Hwa Chae, Sung Hyeon Park, Kyung Yoon Chung, Erhan Deniz, Jang Wook Choi
      Abstract: Pseudocapacitors have received considerable attention, as they possess advantages of both rechargeable batteries and electric double layer capacitors. Among various active materials for pseudocapacitors, α-layered double hydroxides (α-TM(OH)2, TM = transition metal) are promising due to their high specific capacities. Yet, irreversible α-to-β phase transitions of α-TM(OH)2 hinder their long-term cyclability, particularly when the TM is nickel. Here, it is reported that binary TM ion mixing can overcome the limited cycle lives of α-TM(OH)2 by stabilizing the octahedral frameworks of α-TM(OH)2. In particular, an α-TM(OH)2 with equal amounts of nickel and cobalt exhibits long-term capacity retention (89.0% after 2000 cycles) and specific capacity (206 mA h g−1), which are better than those of individual TM counterparts. A series of analyses reveals that the improved performances originate from the synergistic effects between the TM ions; the preferred trivalent state of cobalt ions stabilizes the octahedral framework by accommodating the detrimental Jahn–Teller distortion of Ni3+. The stabilized framework also widens the redox swing range of the nickel up to 4+, thus, increasing the specific capacity of the corresponding α-TM(OH)2. This study indicates that proper mixing of TMs is a prolific approach in enhancing the vital properties of α-TM(OH)2, a promising family of pseudocapacitor materials.An α-layered double hydroxide with equal amounts of nickel and cobalt ions exhibits high performances in specific capacity (206 mA h g−1) and cycle life (89.0% after 2000 cycles) as a pseudocapacitor electrode material. These electrochemical properties are attributed to the synergistic interplay of d-electrons of both transition metal ions upon their solid-solution mixing.
      PubDate: 2016-12-29T10:55:57.009666-05:
      DOI: 10.1002/adfm.201605225
       
  • High-Performance UV–Vis–NIR Phototransistors Based on
           Single-Crystalline Organic Semiconductor–Gold Hybrid Nanomaterials
    • Authors: Ji Hyung Jung; Min Ji Yoon, Ju Won Lim, Yoon Ho Lee, Kang Eun Lee, Dong Ha Kim, Joon Hak Oh
      Abstract: Hybrid materials in optoelectronic devices can generate new functionality or provide synergistic effects that enhance the properties of each component. Here, high-performance phototransistors with broad spectral responsivity in UV–vis–near-infrared (NIR) regions, using gold nanorods (Au NRs)-decorated n-type organic semiconductor and N,N′-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI) nanowires (NWs) are reported. By way of the synergistic effect of the excellent photo-conducting characteristics of single-crystalline BPE-PTCDI NW and the light scattering and localized surface plasmon resonances (LSPR) of Au NRs, the hybrid system provides new photo-detectivity in the NIR spectral region. In the UV–vis region, hybrid nanomaterial-based phototransistors exhibit significantly enhanced photo-responsive properties with a photo-responsivity (R) of 7.70 × 105 A W−1 and external quantum efficiency (EQE) of 1.42 × 108% at the minimum light intensity of 2.5 µW cm−2, which are at least tenfold greater than those of pristine BPE-PTCDI NW-based ones and comparable to those of high-performance inorganic material-based devices. While a pristine BPE-PTCDI NW-based photodetector is insensitive to the NIR spectral region, the hybrid NW-based phototransistor shows an R of 10.7 A W−1 and EQE of 1.35 × 103% under 980 nm wavelength-NIR illumination. This work demonstrates a viable approach to high-performance photo-detecting systems with broad spectral responsivity.Optoelectrical performances of phototransistors based on gold nanorods-decorated n-type single-crystalline organic semiconductor nanowires are reported. Owing to the synergy among the excellent photo-conducting characteristics of organic nanowire, the scattering effect and localized surface plasmon resonances of gold nanorods, the hybrid system exhibits broad spectral responsivity with unprecedented performances that are comparable to those of inorganic materials-based phototransistors.
      PubDate: 2016-12-29T09:55:26.399259-05:
      DOI: 10.1002/adfm.201604528
       
  • In Situ Reversible Ionic Control for Nonvolatile Magnetic Phases in a
           Donor/Acceptor Metal-Organic Framework
    • Authors: Kouji Taniguchi; Keisuke Narushima, Hajime Sagayama, Wataru Kosaka, Nanami Shito, Hitoshi Miyasaka
      Abstract: Reversible magnetic control by electrical means, which is highly desired from the viewpoint of fundamentals and technological applications such as data storage devices, has been a challenging topic. In this study, the authors demonstrate in situ magnetic phase switching between the ferrimagnetic and paramagnetic states of an electron-donor/-acceptor metal-organic framework (D/A-MOF) using band-filling control mediated by the Li+-ion migration that accompanies redox reactions, i.e., “magneto-ionic control”. By taking advantage of the rechargeability of lithium-ion battery systems, in which Li+-ions and electrons are simultaneously inserted into/extracted from a cathode material, the reversible control of nonvolatile magnetic phases in a D/A-MOF has been achieved. This result demonstrates that the combination of a redox-active MOF with porous flexibility and ion-migration capability enables the creation of new pathways toward magneto-electric coupling devices in the field of ionics.In situ reversible magnetic phase switching between nonvolatile paramagnetic and ferrimagnetic states has been demonstrated in an electron-donor/-acceptor metal-organic framework by a lithium ion battery (LIB) system. Selective electron-filling control of acceptor sites based on the LIB voltage has been achieved by the Li+-ion migration accompanying redox reaction; magneto-ionic control. On/off switching of exchange interaction paths has been realized.
      PubDate: 2016-12-29T08:30:41.74247-05:0
      DOI: 10.1002/adfm.201604990
       
  • Ag/Ag2S Nanocrystals for High Sensitivity Near-Infrared Luminescence
           Nanothermometry
    • Authors: Diego Ruiz; Blanca del Rosal, María Acebrón, Cristina Palencia, Chen Sun, Juan Cabanillas-González, Miguel López-Haro, Ana B. Hungría, Daniel Jaque, Beatriz H. Juarez
      Abstract: Temperature sensing in biological media (cells, tissues, and living organisms) has become essential in the development of the last generation of diagnostics and therapeutic strategies. Thermometry can be used for early detection of different diseases, such as cancer, stroke, or inflammation processes, one of whose incipient symptoms is the appearance of localized temperature singularities. Luminescence nanothermometry, as a tool to accurately provide temperature sensing in biological media, requires the rational design and development of nanothermometers operating in the second biological window. In this work, this is achieved using Ag/Ag2S nanocrystals as multiparametric thermal sensing probes. Temperature sensing with remarkably high sensitivity (4% °C−1) is possible through intensity-based measurements, as their infrared emission is strongly quenched by small temperature variations within the biological range (15–50 °C). Heating also results in a remarkable redshift of the emission band, which allows for concentration-independent temperature sensing based on infrared ratiometric measurements, with thermal sensitivity close to 2% °C−1. These results make Ag/Ag2S nanocrystals the most sensitive among all noncomposite nanothermometers operating in the second biological window reported so far, allowing for deep-tissue temperature measurements with low uncertainty (0.2 °C).The outstanding infrared fluorescence thermal sensing capabilities of Ag2S nanocrystals are reported. Ag2S nanocrystals are here introduced to the scientific community as thermal nanoprobes capable of real-time subcutaneous contactless temperature sensing with a subdegree resolution. In combination with their long-term stability and low toxicity, their thermal sensing capabilities make Ag2S nanocrystals unique bioprobes.
      PubDate: 2016-12-28T03:15:44.98726-05:0
      DOI: 10.1002/adfm.201604629
       
  • Graphene-Piezoelectric Material Heterostructure for Harvesting Energy from
           Water Flow
    • Authors: Huikai Zhong; Jun Xia, Fengchao Wang, Hongsheng Chen, Hengan Wu, Shisheng Lin
      Abstract: Recently, liquid flow over monolayer graphene has been experimentally demonstrated to generate an induced voltage in the flow direction, and various physical mechanisms have been proposed to explain the electricity-generating process between liquid and graphene. However, there are significant discrepancies in the reported results with non-ionic liquid: the observed voltage responses with deionized (DI) water vary from lab to lab under presumably similar flowing conditions. Here, a graphene-piezoelectric material heterostructure is proposed for harvesting energy from water flow; it is shown that the introduction of a piezoelectric template beneath graphene results in an obvious voltage output up to 0.1 V even with DI water. This potential arises from a continuous charging–discharging process in graphene, which is suggested to be a result of a relatively retarded screening effect of the water for the generated piezoelectric charges than that of the graphene layer, as revealed by first-principles calculations. This work considers a dynamic charge interaction among water, graphene, and the substrate, highlighting the crucial role of the underlying substrate in the electricity-generating process, which will greatly enhance understanding of the flow-induced voltage and push the graphene-water nanogenerator close to practical applications.Through introducing piezoelectric template beneath graphene, moving droplets of deionized water along the graphene surface can induce an electric potential. This electricity is suggested to be a result of a dynamic charge interaction among water, graphene, and the piezoelectric substrate, which highlights the crucial role of the underlying substrate in the electricity generating process.
      PubDate: 2016-12-28T03:05:37.93605-05:0
      DOI: 10.1002/adfm.201604226
       
  • Wearable Force Touch Sensor Array Using a Flexible and Transparent
           Electrode
    • Authors: Jun-Kyul Song; Donghee Son, Jaemin Kim, Young Jin Yoo, Gil Ju Lee, Liu Wang, Moon Kee Choi, Jiwoong Yang, Mincheol Lee, Kyungsik Do, Ja Hoon Koo, Nanshu Lu, Ji Hoon Kim, Taeghwan Hyeon, Young Min Song, Dae-Hyeong Kim
      Abstract: Transparent electrodes have been widely used for various electronics and optoelectronics, including flexible ones. Many nanomaterial-based electrodes, in particular 1D and 2D nanomaterials, have been proposed as next-generation transparent and flexible electrodes. However, their transparency, conductivity, large-area uniformity, and sometimes cost are not yet sufficient to replace indium tin oxide (ITO). Furthermore, the conventional ITO is quite rigid and susceptible to mechanical fractures under deformations (e.g., bending, folding). In this study, the authors report new advances in the design, fabrication, and integration of wearable and transparent force touch (touch and pressure) sensors by exploiting the previous efforts in stretchable electronics as well as novel ideas in the transparent and flexible electrode. The optical and mechanical experiment, along with simulation results, exhibit the excellent transparency, conductivity, uniformity, and flexibility of the proposed epoxy-copper-ITO (ECI) multilayer electrode. By using this multi-layered ECI electrode, the authors present a wearable and transparent force touch sensor array, which is multiplexed by Si nanomembrane p-i-n junction-type (PIN) diodes and integrated on the skin-mounted quantum dot light-emitting diodes. This novel integrated system is successfully applied as a wearable human–machine interface (HMI) to control a drone wirelessly. These advances in novel material structures and system-level integration strategies create new opportunities in wearable smart displays.A novel transparent and flexible electrode, composed of an epoxy-copper-indium tin oxide (ECI) multilayer is presented. Enhanced optical transparency, mechanical deformability, and electrical conductivity of the ECI multilayer allow for the development of a transparent and wearable human–machine interface system. The system is composed of the touch and pressure sensor array multiplexed by Si nanomembrane diodes and is integrated with wearable quantum dot light-emitting diodes. A drone can be wirelessly controlled by the developed wearable force touch sensor array.
      PubDate: 2016-12-28T03:05:33.853914-05:
      DOI: 10.1002/adfm.201605286
       
  • Determination of Urinary 1-Hydroxypyrene for Biomonitoring of Human
           Exposure to Polycyclic Aromatic Hydrocarbons Carcinogens by a
           Lanthanide-functionalized Metal-Organic Framework Sensor
    • Authors: Ji-Na Hao; Bing Yan
      Abstract: 1-Hydroxypyrene (1-HP), which is a biomarker of polycyclic aromatic hydrocarbons (PAHs) carcinogens and represents the internal dose of PAHs exposure in the human body, is detected by a newly designed luminescent Eu-functionalized metal-organic framework (1a) sensor. The luminescence of 1a can be effectively quenched by 1-HP via a fluorescent resonant energy transfer process, thus achieving its recognition of 1-HP. This is the first use of lanthanide metal-organic frameworks (Ln-MOFs) as chemical sensors for 1-HP. The probe exhibits outstanding performances for sensing 1-HP, such as high selectivity, excellent sensitivity, fast response, and good reusability. Importantly, the sensing system enables the detection of 1-HP in real human urine specimens, and a portable 1-HP urine test paper is also developed. Hence, the reported 1-HP sensing platform has promising application potential for clinical diagnosis of the intoxication level of PAHs.A novel europium-functionalized metal-organic framework is constructed that can act as the first example of a fluorescent sensor for urinary 1-hydroxypyrene, which is the metabolite and biomarker of human exposure to polycyclic aromatic hydrocarbons carcinogens.
      PubDate: 2016-12-27T07:16:14.9812-05:00
      DOI: 10.1002/adfm.201603856
       
  • Active Regulation of On-Demand Drug Delivery by Magnetically Triggerable
           Microspouters
    • Authors: Ali Shademani; Hongbin Zhang, John K. Jackson, Mu Chiao
      Abstract: Triggerable devices capable of on-demand, controlled release of therapeutics are attractive options for the treatment of local diseases because of their potential to enhance therapeutic effectiveness with reduced systemic toxicity. Here, the design and fabrication of a miniaturized device, termed a microspouter, is described. This device is shown to provide active and precise control of localized delivery of drugs on demand. The microspouter is composed of a magnetic sponge to provide the force for drug release through magnetic field-induced reversible deformation, a reservoir for the sponge installation and drug loading, and a soft membrane for sealing the device. Following application of a magnetic field to the microspouter, the shrinking of the sponge may trigger a spouting of drug through a membrane's microaperture. The efficiency of the device in controlling the dose and time course of drug release under different external magnetic fields has been demonstrated using methylene blue and docetaxel as model drugs. Additionally, the microspouter is found to have low background drug leakage that allows for tunable drug release in an ex vivo implantation experiment. All the results confirm the microspouter as a potential device for safe, long-time, and controlled drug release in local disease treatment.A triggerable device, termed a microspouter, is designed and fabricated for active and precise control of localized drug delivery. It is able to be triggered to spout drug solution on demand through external magnetic stimuli to achieve a safe and long-time controlled drug release.
      PubDate: 2016-12-27T07:11:14.553068-05:
      DOI: 10.1002/adfm.201604558
       
  • 1T-Phase WS2 Protein-Based Biosensor
    • Authors: Rou Jun Toh; Carmen C. Mayorga-Martinez, Zdenek Sofer, Martin Pumera
      Abstract: Metallic 1T-phase transition metal dichalcogenides have been recognized for their desirable properties like high surface-to-volume ratio, high conductivity, and capacitive behavior, making them outstanding for catalytic and sensing applications. Herein, a hydrogen peroxide (H2O2) biosensor is constructed by the immobilization of hemoglobin (Hb) on 1T-phase WS2 (1T-WS2) sheets, and entrapment by glutaraldehyde. 1T-WS2 not only displays electrocatalytic activity toward the reduction of H2O2 but also provides a high surface-to-volume ratio and conductive platform for the immobilization of Hb and facilitation of its electron transfer to the electrode surface. The advantageous role of 1T-phase WS2 is further demonstrated for the construction of a heme-based H2O2 biosensor compared to its 1T-phase MoS2, MoSe2, and WSe2 counterparts. Synergistic interactions between 1T-WS2 and Hb result in a H2O2 biosensor with high analytical performance in terms of wide range, sensitivity, selectivity, reproducibility, repeatability, and stability. These findings have profound impact in the research fields of electrochemical sensing and biodiagnostics.Synergistic effects between 1T-phase WS2 and hemoglobin result in a high-performing hydrogen peroxide (H2O2) biosensor compared to its 1T-phase MoS2, MoSe2, and WSe2 counterparts. 1T-phase WS2 displays electrocatalytic activity toward the reduction of H2O2 and serves as a high surface-to-volume ratio and conductive platform for hemoglobin immobilization and facilitation of its electron transfer to the electrode surface.
      PubDate: 2016-12-27T07:11:09.298128-05:
      DOI: 10.1002/adfm.201604923
       
  • High-Performance Organic Heterojunction Phototransistors Based on Highly
           Ordered Copper Phthalocyanine/para-Sexiphenyl Thin Films
    • Authors: Chuan Qian; Jia Sun, Ling-An Kong, Guangyang Gou, Menglong Zhu, Yongbo Yuan, Han Huang, Yongli Gao, Junliang Yang
      Abstract: High-performance organic heterojunction phototransistors are fabricated using highly ordered copper phthalocyanine (CuPc) and para-sexiphenyl (p-6P) thin films. The p-6P thin film plays an important role on the performance of CuPc/p-6P heterojunction phototransistors. It acts as a molecular template layer to induce the growth of highly ordered CuPc thin film, which dramatically improves the charge transport and decreases the grain boundaries. On the other hand, the p-6P thin film can form an effective heterojunction with CuPc thin film, which is greatly helpful to enhance the light absorption and photogenerated carriers. Under 365 nm ultraviolet light irradiation, the ratio of photocurrent and dark current and photoresponsivity of CuPc/p-6P heterojunction phototransistors reaches to about 2.2 × 104 and 4.3 × 102 A W−1, respectively, which are much larger than that of CuPc phototransistors of about 2.7 × 102 and 7.3 A W−1, respectively. A detailed study carried out with current sensing atomic force microscopy proves that the photocurrent is predominately produced inside the highly ordered CuPc/p-6P heterojunction grains, while the photocurrent produced at the boundaries between grains can be neglected. The research provides a good method for fabricating high-performance organic phototransistors using a combination of molecular template growth and organic heterojunction.High-performance organic heterojunction phototransistors are fabricated using highly ordered copper phthalocyanine (CuPc) and para-sexiphenyl (p-6P) thin films. The ratio of photocurrent and dark current and photoresponsivity reach to about 2.2 × 104 and 4.3 × 102 A W−1, respectively. A detailed study is carried out with current sensing atomic force microscopy.
      PubDate: 2016-12-27T07:11:04.000154-05:
      DOI: 10.1002/adfm.201604933
       
  • Impact of Crystal Surface on Photoexcited States in
           Organic–Inorganic Perovskites
    • Authors: Susanne T. Birkhold; Eugen Zimmermann, Tom Kollek, Daniel Wurmbrand, Sebastian Polarz, Lukas Schmidt-Mende
      Abstract: Despite their outstanding photovoltaic performance, organic–inorganic perovskite solar cells still face severe stability issues and limitations in their device dimension. Further development of perovskite solar cells therefore requires a deeper understanding of loss mechanisms, in particular, concerning the origin and impact of trap states. Here, different surface properties of submicrometer sized CH3NH3PbI3 particles are studied as a model system by photoluminescence spectroscopy to investigate the impact of the perovskite crystal surface on photoexcited states. Comparison of single crystals with either isolating or electron-rich surface passivation indicates the presence of positively charged surface trap states that can be passivated in case of the latter. These surface trap states cause enhanced nonradiative recombination at room temperature, which is a loss mechanism for solar cell performance. In the orthorhombic phase, the origin of multiple emission peaks is identified as the recombination of free and bound excitons, whose population ratio critically depends on trap state properties. The dynamics of exciton trapping at 50 K are observed on a time-scale of tens of picoseconds by a simultaneous population decrease and increase of free and bound excitons, respectively. These results emphasize the potential of surface passivation to further improve the performance of perovskite solar cells.A comparison of electron-rich and isolating surface passivation of submicrometer sized CH3NH3PbI3 single crystals reveals the presence of positively charged trap states at the crystal surface. Photoluminescence measurements at different temperatures demonstrate that these surface trap states cause surface lattice distortions and nonradiative recombination at room temperature and energy transfer from free excitons to bound excitons at low temperatures.
      PubDate: 2016-12-27T07:10:58.754429-05:
      DOI: 10.1002/adfm.201604995
       
  • Selenium-Containing Polymer@Metal-Organic Frameworks Nanocomposites as an
           Efficient Multiresponsive Drug Delivery System
    • Authors: Weiqiang Zhou; Lu Wang, Feng Li, Weina Zhang, Wei Huang, Fengwei Huo, Huaping Xu
      Abstract: The development of efficient multiresponsive drug delivery systems (DDSs) to control drug release has been widely explored. Herein, a facile strategy is reported that enables the micelles of the selenium-containing polymer with the drug to be encapsulated in metal-organic frameworks (MOFs), which serves as multiresponsive drug release by employing the selenium-containing polymers with redox-triggered property and the MOFs with pH-triggered property in DDS. In this case, the micelles of selenium-containing polymers, as core easily disassembles in the presence of redox agents, can then release the drug in MOFs matrixes. The ZIF-8 (one type of MOFs) crystal frameworks serving as shell can collapse only under low pH conditions, and the drug can be further released. In the presence of external redox agents as well as the pH stimuli, the prepared nanocomposite (P@ZIF-8) drug system exhibits the capability of multiresponsive release of the doxorubicin (DOX) and possesses good selectivity in releasing the DOX under low pH conditions instead of normal pH conditions. In addition, the merits of P@ZIF-8 such as good biocompatibility, multiresponsive release properties, and especially the selective release properties under different pH conditions make the materials highly promising candidates for the realization of controlled drug delivery in tumor tissue systems.The multiresponsive P@ZIF-8 as an advanced biocompatible drug delivery system (DDS) has been successfully prepared. The as-prepared P@ZIF-8 has excellent biocompatibility, good loading capacity, and controllable drug release and is suitable for doxorubicin storage/release as a smart DDS. These results suggest that hybrid nanocomposites may provide new possibilities for controllable drug release in biomaterials.
      PubDate: 2016-12-27T07:10:54.454954-05:
      DOI: 10.1002/adfm.201605465
       
  • Activating Basal Planes and S-Terminated Edges of MoS2 toward More
           Efficient Hydrogen Evolution
    • Authors: Xiaolei Huang; Mei Leng, Wen Xiao, Meng Li, Jun Ding, Teck Leong Tan, Wee Siang Vincent Lee, Junmin Xue
      Abstract: Molybdenum disulfide (MoS2) has been considered as a promising alternative to platinum (Pt)-based catalyst for hydrogen evolution reaction (HER) due to its low cost and high catalytic activity. However, stable 2H phase of MoS2 (2H-MoS2) exhibits low catalytic activity in HER due to the inert basal plane and S-edge. Thus, to exploit the basal plane and S-edge for additional electrocatalytic activity, a facile strategy is developed to prepare P-doped 2H-MoS2 film on conductive substrate via low-temperature heat treatment. Due to the inherent difficulty of P-doping into MoS2 crystal structure, oxygen (O)-doping is utilized to aid the P-doping process, as supported by the first-principles calculations. Interestingly, P-doping could dramatically reduce Mo valence charge, which results in the functionalization of the inert MoS2 basal plane and S-edge. In agreement with simulation results, P-doped 2H-MoS2 electrode exhibits enhanced catalytic performance in H2 generation with low onset potential (130 mV) and small Tafel slope of 49 mV dec−1. The enhanced catalytic performance arises from the synergistic effect of the activated basal plane, S-edge, and Mo-edge sites, leading to favorable hydrogen adsorption energies. Most importantly, improved cyclic stability is achieved, which reveals chemically inert properties of P-doped 2H-MoS2 in acidic electrolyte.P-doped MoS2 is synthesized via a facile, efficient, and low-temperature non-metal doping method, whereby O-doping plays a crucial role in lowering the formation energies. P-doping can dramatically decrease hydrogen evolution reaction overpotential due to the lowering of Mo valance charge, hence promoting electron transfer from MoS2 to hydrogen ions.
      PubDate: 2016-12-27T07:10:50.766062-05:
      DOI: 10.1002/adfm.201604943
       
  • Hydrogels That Actuate Selectively in Response to Organophosphates
    • Authors: Manos Gkikas; Reginald K. Avery, Carolyn E. Mills, Ramanathan Nagarajan, Eugene Wilusz, Bradley D. Olsen
      Abstract: Nerve agents and pesticides represent a category of extremely toxic organophosphate compounds (OPs) that irreversibly inhibit the enzyme acetylcholinesterase, disturbing transmission in the synaptic clefts of muscles and nerves. Protection from these compounds necessitates the development of breathable barriers that can selectively block the passage of OPs. Hydrogels prepared from acrylamide, N,N′-methylenebis(acrylamide), N,N′-bis(acryloyl)cystamine, and hydrophilic pendant oximes are herein prepared, showing the ability to decontaminate and respond to the presence of OPs through a change in swelling. The oxime-based hydrogels show selective response only to malaoxon when tested against chemicals that are found in sweat as well as other reactive chemicals that are found in the environment. Pore sealing is demonstrated in perforated equilibrated gels within 3–4 h after the addition of malaoxon, showing actuation of the gel in response to organophosphates. This strategy demonstrates the ability to couple oxime-based decontamination and disulfide chemistry to produce hydrogels that can decontaminate organophosphate compounds, sense the decontamination product, and transduce this sensing response into actuation of the gel, which can be used to close pores in gel sheets or between fibers in a protective fabric coating.Acrylamide-based hydrogels containing oxime pendant groups are shown to decontaminate and actuate in response to contact with V-type organophosphates such as malaoxon. The mechanical actuation, leading to pore closing, is the result of disulfide cross-link cleavage triggered by the organophosphate decontamination products, yielding dissolution or swelling of the hydrogel. This technology is applied in both hydrogel sheets and hydrogel-impregnated fabrics.
      PubDate: 2016-12-27T07:10:46.832316-05:
      DOI: 10.1002/adfm.201602784
       
  • Nanoparticle Assisted Mechanical Delamination for Freestanding High
           Performance Organic Devices
    • Authors: Silvia Colodrero; Pablo Romero-Gomez, Paola Mantilla-Perez, Jordi Martorell
      Abstract: Organic electronics has the potential to be incorporated in any kind of surface morphology for wearable or fully portable applications. Unfortunately when organic devices, such as solar cells, are fabricated on flexible substrates, the device performance is severely limited unless the physical properties of such substrates are carefully chosen. Here, it is demonstrated that layers of nanoparticles with a size gradient distribution can be used to obtain high performance solar cell devices that can be effectively delaminated from an original flat and rigid glass substrate. Such sacrificial nanoparticles layers are incorporated in between the glass substrate and the semitransparent electrode of a polymer:fullerene (PTB7:PC71BM) cell. After the cell delamination, freestanding flexible devices with power conversion efficiencies as high as 7.12% are obtained, which corresponds to 90% of the performance of the same cell fabricated on a standard glass smooth surface.The performance of flexible electronic devices is, in general, strongly limited by the physical properties of the specific substrate used. It is demonstrated that a sacrificial layer of multiple size nanoparticles with a size gradient distribution can be used to successfully delaminate organic solar cells from an original flat and rigid glass substrate to achieve efficient freestanding flexible devices.
      PubDate: 2016-12-09T07:08:19.400476-05:
      DOI: 10.1002/adfm.201602969
       
  • Black Gold: Broadband, High Absorption of Visible Light for Photochemical
           Systems
    • Authors: Charlene Ng; Lim Wei Yap, Ann Roberts, Wenlong Cheng, Daniel E. Gómez
      Abstract: Here, a black Au surface is presented: a material solely composed of Au that is capable of absorbing more than 92% of the incident light over a spectral region ranging from 300 to 600 nm and that can maintain a high absorbance (above 70%) for wavelengths up to 800 nm. The black Au surface is fabricated by a simple and scalable template-assisted physical vapor deposition technique and possesses the flexibility of adhering to any arbitrary substrate. The high absorbance of Au originates from the close packing of high aspect ratio Au nanotubes possessing a random tapered wall thickness. Fabry–Perot resonances of gap-plasmon modes between the Au nanotubes are also responsible for the strong suppression of reflectance of black Au as demonstrated by finite element method simulations. Furthermore, the ability of this surface to drive photochemical transformations under visible light illumination is demonstrated. Hence, black Au could provide a new paradigm for the use of highly absorbing metal nanostructures to effectively harvest the entire visible spectrum for photorelated applications such as solar fuel production, photodetection, and photovoltaics.A novel black gold material that exhibits broadband high absorption of visible light is presented. It consists of closely packed gold nanotubes with tapered wall thickness. The high light-absorbing property can be applied to visible light photochemical systems and function as an efficient photocatalyst over a broad range of wavelengths.
      PubDate: 2016-11-28T08:00:34.188457-05:
      DOI: 10.1002/adfm.201604080
       
  • “Black” Titania Coatings Composed of Sol–Gel Imprinted
           Mie Resonators Arrays
    • Authors: Thomas Bottein; Thomas Wood, Thomas David, Jean Benoît Claude, Luc Favre, Isabelle Berbézier, Antoine Ronda, Marco Abbarchi, David Grosso
      Abstract: Optical technologies and devices rely on the controlled manipulation of light propagation through a medium. This is generally governed by the inherent effective refractive index of the material as well as by its structure and dimensionality. Although a precise control over light propagation with sub-wavelength size objects is a crucial issue for a plethora of applications, the widely used fabrication methods remain cumbersome and expensive. Here, a sol–gel dip-coating method combined with nanoimprinting lithography on arbitrary glass and silicon substrates is implemented for the fabrication of TiO2-based dielectric Mie resonators. The technique allows obtaining sub-micrometric pillars featuring unprecedented vertical aspect ratios (>1) with relatively high fidelity and precision. Spectroscopic characterization at visible and near-infrared frequencies demonstrate that the resonant properties of these dielectric pillar arrays allow for a drastic reduction of light transmission (cutting more than 50% on glass) and reduced reflection (reflecting less than 3% on glass and 16% on bulk silicon), accounting for an efficient light trapping. These results provide a guideline for the fabrication of Mie resonators using a fast, versatile, low-cost, low-temperature technique for efficient light manipulation at the nanoscale.Titania-based dielectric Mie resonators (MRs) are fabricated via a joint sol–gel dip-coating and soft-nanoimprint lithography method. The coating of SiO2 glass substrates with TiO2 MRs allows for large modifications of light propagation, leading to reduced reflection and transmission owing to an efficient light trapping effect. The same fabrication methodology applied to a silicon substrate produces an efficient broad band antireflection coating.
      PubDate: 2016-11-23T05:30:38.855308-05:
      DOI: 10.1002/adfm.201604924
       
  • Transition Metal Dichalcogenide-Based Transistor Circuits for Gray Scale
           Organic Light-Emitting Displays
    • Authors: Sanghyuck Yu; Jin Sung Kim, Pyo Jin Jeon, Jongtae Ahn, Jae Chul Park, Seongil Im
      Abstract: Two types of transition metal dichalcogenide (TMD) transistors are applied to demonstrate their possibility as switching/driving elements for the pixel of organic light-emitting diode (OLED) display. Such TMD materials are 6 nm thin WSe2 and MoS2 as a p-type and n-type channel, respectively, and the pixel is thus composed of external green OLED and nanoscale thin channel field effect transistors (FETs) for switching and driving. The maximum mobility of WSe2-FETs either as switch or as driver is ≈30 cm2 V−1 s−1, in linear regime of the gate voltage sweep range. Digital (ON/OFF-switching) and gray-scale analogue operations of OLED pixel are nicely demonstrated. MoS2 nanosheet FET-based pixel is also demonstrated, although limited to alternating gray scale operation of OLED. Device stability issue is still remaining for future study but TMD channel FETs are very promising and novel for their applications to OLED pixel because of their high mobility and ID ON/OFF ratio.2D transition metal dichalcogenides (TMD), WSe2, and MoS2 are used to demonstrate their performances in pixels of organic light-emitting diode (OLED) displays. The pixel is composed of an external green OLED and TMD-channel driving/switching transistors. Digital (ON/OFF-switching) and gray-scale analogue operations of OLED pixels are nicely demonstrated.
      PubDate: 2016-11-23T05:30:27.966343-05:
      DOI: 10.1002/adfm.201603682
       
  • Organic–Inorganic Hierarchical Self-Assembly into Robust Luminescent
           Supramolecular Hydrogel
    • Authors: Zhiqiang Li; Zhaohui Hou, Hongxian Fan, Huanrong Li
      Abstract: Luminescent hydrogels are of great potential for many fields, particularly serving as biomaterials ranging from fluorescent sensors to bioimaging agents. Here, robust luminescent hydrogels are reported using lanthanide complexes as emitting sources via a hierarchical organic–inorganic self-assembling strategy. A new organic ligand is synthesized, consisting of a terpyridine unit and two flexibly linked methylimidazole moieties to coordinate with europium(III) (Eu3+) tri-thenoyltrifluoroacetone (Eu(TTA)3), leading to a stable amphiphilic Eu3+-containing monomer. Synergistic coordination of TTA and terpyridine units allows the monomer to self-assemble into spherical micelles in water, thus maintaining the luminescence of Ln complexes in water. The micelles further coassemble with exfoliated Laponite nanosheets coated with sodium polyacrylate into networks based on the electrostatic interactions, resulting in the supramolecular hydrogel possessing strong luminescence, extraordinary mechanical property, as well as self-healing ability. The results demonstrate that hierarchical organic–inorganic self-assembly is a versatile and effective strategy to create luminescent hydrogels containing lanthanide complexes, giving rise to great potential applications as a soft material.A luminescent supramolecular hydrogel using lanthanide complexes as emitting sources is constructed via a hierarchical organic–inorganic self-assembling strategy, showing ultrastrong mechanical performance and extraordinary photophysical property.
      PubDate: 2016-11-18T02:25:45.955807-05:
      DOI: 10.1002/adfm.201604379
       
  • Synergistic Effect of Hybrid PbS Quantum Dots/2D-WSe2 Toward High
           Performance and Broadband Phototransistors
    • Authors: Chao Hu; Dongdong Dong, Xiaokun Yang, Keke Qiao, Dun Yang, Hui Deng, Shengjie Yuan, Jahangeer Khan, Yang Lan, Haisheng Song, Jiang Tang
      Abstract: The transitionmetal dichalcogenides-based phototransistors have demonstrated high transport mobility but are limited to poor photoresponse, which greatly blocks their applications in optoelectronic fields. Here, light sensitive PbS colloidal quantum dots (QDs) combined with 2D WSe2 to develop hybrid QDs/2D-WSe2 phototransistors for high performance and broadband photodetection are utilized. The device shows a responsivity up to 2 × 105 A W–1, which is orders of magnitude higher than the counterpart of individual material-based devices. The detection spectra of hybrid devices can be extended to near infrared similar to QDs' response. The high performance of hybrid 0D-2D phototransistor is ascribed to the synergistic function of photogating effect. PbS QDs can efficiently absorb the input illumination and 2D WSe2 supports a transport expressway for injected photocarriers. The hybrid phototransistors obtain a specific detectivity over 1013 Jones in both ON and OFF state in contrast to the depleted working state (OFF) for other reported QDs/2D phototransistors. The present device construction strategy, photogating enhanced performance, and robust device working conditions contain high potential for future optoelectronic devices.High performance hybrid phototransistors for broadband detection based on PbS QDs and 2D WSe2 monolayer are demonstrated. Owing to the synergistic effect of high mobility of WSe2 nanosheet and strong light absorption of PbS QD layer, high responsivity of up to 105 A W–1 is achieved. Further study unfolds the main mechanism, which is attributed to the photogating effect.
      PubDate: 2016-11-16T08:46:32.154799-05:
      DOI: 10.1002/adfm.201603605
       
  • Chiroptical Resolution and Thermal Switching of Chirality in Conjugated
           Polymer Luminescence via Selective Reflection using a Double-Layered Cell
           of Chiral Nematic Liquid Crystal
    • Authors: Jialin Yan; Fuyuki Ota, Benedict A. San Jose, Kazuo Akagi
      Abstract: An optically resolvable and thermally chiral-switchable device for circularly polarized luminescence (CPL) is first constructed using a light-emitting conjugated polymer film and a double-layered chiral nematic liquid crystal (N*-LC) cell. The double-layered N*-LC cell with opposite handedness at each layer is fabricated by adding each of two types of N*-LCs into each of the cells, and the N*-LCs consist of nematic LCs and chiral dopants with opposite chirality and different mole concentrations. The selective reflection band due to the N*-LC is thermally shifted so that the band wavelength is close to the luminescence band of the racemic conjugated polymer, such as disubstituted polyacetylene (diPA), yielding CPL with opposite handedness and high dissymmetry factor values ( glum ) of 1.1–1.6 at low and high temperatures. The double-layered N*-LC cell bearing the temperature-controlled selective reflection is useful for generating CPLs from racemic fluorescent materials and for allowing thermal chirality-switching in CPLs, which present new possibilities for optoelectronic and photochemical applications.An optically resolvable and thermally chiral-switchable device for circularly polarized luminescence (CPL) is constructed using a light-emitting conjugated polymer film and a double-layered cell of chiral nematic liquid crystal (N*-LC) with opposite handedness at each layer. The chirality switching of the CPL is achieved via selective reflections of the N*-LCs with different helical senses.
      PubDate: 2016-11-15T08:04:06.793645-05:
      DOI: 10.1002/adfm.201604529
       
  • Materials and Device Designs for an Epidermal UV Colorimetric Dosimeter
           with Near Field Communication Capabilities
    • Authors: Hitoshi Araki; Jeonghyun Kim, Shaoning Zhang, Anthony Banks, Kaitlyn E. Crawford, Xing Sheng, Philipp Gutruf, Yunzhou Shi, Rafal M. Pielak, John A. Rogers
      Abstract: Ultraviolet (UV) solar radiation is a leading cause of skin disease. Quantitative, continuous knowledge of exposure levels can enhance awareness and lead to improved health outcomes. Devices that offer this type of measurement capability in formats that can seamlessly integrate with the skin are therefore of interest. This paper introduces materials, device designs, and data acquisition methods for a skin-like, or “epidermal,” system that combines colorimetric and electronic function for precise dosimetry in the UV-A and UV-B regions of the spectrum, and for determination of instantaneous UV exposure levels and skin temperature. The colorimetric chemistry uses (4-phenoxyphenyl)diphenylsulfonium triflate (PPDPS-TF) with crystal violet lactone (CVL) and Congo red for UV-A and UV-B operation, respectively, when integrated with suitable optical filters. Coatings of poly(ethylene-vinylacetate) (PEVA) protect the functional materials from sunscreen and other contamination. Quantitative information follows from automated L*a*b* color space analysis of digital images of the devices to provide accurate measurements when calibrated against standard nonwearable sensors. Techniques of screen printing and lamination allow aesthetic designs and integration with epidermal near field communication platforms, respectively. The result is a set of attractive technologies for managing UV exposure at a personal level and on targeted regions of the body.This paper introduces materials, device designs, and data acquisition methods for a skin-like, or “epidermal,” system that combines colorimetric and wireless electronic function for precise dosimetry in the UV-A and UV-B regions, and for the determination of instantaneous UV exposure levels and skin temperature. Quantitative information follows from automated color analysis of digital images, as validated against digital measurement systems.
      PubDate: 2016-11-15T07:58:47.028607-05:
      DOI: 10.1002/adfm.201604465
       
  • Piezoelectric Nylon-11 Nanowire Arrays Grown by Template Wetting for
           Vibrational Energy Harvesting Applications
    • Authors: Anuja Datta; Yeon Sik Choi, Evie Chalmers, Canlin Ou, Sohini Kar-Narayan
      Abstract: Piezoelectric polymers, capable of converting mechanical vibrations into electrical energy, are attractive for use in vibrational energy harvesting due to their flexibility, robustness, ease, and low cost of fabrication. In particular, piezoelectric polymers nanostructures have been found to exhibit higher crystallinity, higher piezoelectric coefficients, and “self-poling,” as compared to films or bulk. The research in this area has been mainly dominated by polyvinylidene fluoride and its copolymers, which while promising have a limited temperature range of operation due to their low Curie and/or melting temperatures. Here, the authors report the fabrication and properties of vertically aligned and “self-poled” piezoelectric Nylon-11 nanowires with a melting temperature of ≈200 °C, grown by a facile and scalable capillary wetting technique. It is shown that a simple nanogenerator comprising as-grown Nylon-11 nanowires, embedded in an anodized aluminium oxide (AAO) template, can produce an open-circuit voltage of 1 V and short-circuit current of 100 nA, when subjected to small-amplitude, low-frequency vibrations. Importantly, the resulting nanogenerator is shown to exhibit excellent fatigue performance and high temperature stability. The work thus offers the possibility of exploiting a previously unexplored low-cost piezoelectric polymer for nanowire-based energy harvesting, particularly at temperatures well above room temperature.Vertically aligned arrays of piezoelectric Nylon-11 nanowires with high aspect ratio are prepared using a capillary template wetting method within nanoporous anodized alumina templates. The template-grown nanowires are “self-poled” and thus can be directly incorporated into nanogenerators with excellent fatigue performance. The relatively high melting temperature (≈200 °C) of these nanowires makes them suitable for energy harvesting applications at elevated temperatures.
      PubDate: 2016-11-11T04:55:59.86763-05:0
      DOI: 10.1002/adfm.201604262
       
  • Molecular Engineering of Highly Efficient Small Molecule Nonfullerene
           Acceptor for Organic Solar Cells
    • Authors: Suman; Vinay Gupta, Anirban Bagui, Surya Prakash Singh
      Abstract: A new molecularly engineered nonfullerene acceptor, 2,2′-(5,5′-(9,9-didecyl-9H-fluorene-2,7-diyl)bis(benzo[c][1,2,5]thiadiazole-7,4-diyl)bis(methanylylidene))bis(3-hexyl-1,4-oxothiazolidine-5,2-diylidene))dimalononitrile (BAF-4CN), with fluorene as the core and arms of dicyano-n-hexylrhodanine terminated benzothiadiazole is synthesized and used as an electron acceptor in bulk heterojunction organic solar cells. BAF-4CN shows a stronger and broader absorption with a high molar extinction coefficient of 7.8 × 104m−1 cm−1 at the peak position (498 nm). In the thin film, the molecule shows a redshift around 17 nm. The photoluminescence experiments confirm the excellent electron accepting nature of BAF-4CN with a Stern–Volmer coefficient (Ksv) of 1.1 × 105m−1. From the electrochemical studies, the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of BAF-4CN are estimated to be −5.71 and −3.55 eV, respectively, which is in good synchronization with low bandgap polymer donors. Using BAF-4CN as an electron acceptor in a poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3″′-di(2-octyldodecyl) 2,2′;5′,2″;5″,2″′-quaterthiophen-5,5″′-diyl)] based bulk-heterojunction solar cell, a maximum power conversion efficiency of 8.4% with short-circuit current values of 15.52 mA cm−2, a fill factor of 70.7%, and external quantum efficiency of about 84% covering a broad range of wavelength is achieved.The non-fullerene acceptor (NFA) BAF-4CN is synthesized for organic photovoltaic (OPV) application to overcome the drawbacks of fullerene. BAF-4CN shows stronger absorption compared to phenyl C71-butyric acid methyl ester and has an excellent electron accepting nature and high charge carrier mobility. A power conversion efficiency of 8.4% is achieved from PffBT4T-2OD:BAF-4CN based bulk heterojunction solar cells. This may be a promising substitute for fullerene in low-cost solution-processed OPV.
      PubDate: 2016-11-10T08:55:58.357462-05:
      DOI: 10.1002/adfm.201603820
       
  • Peptide-Enhanced Selective Surface Deposition of Polymer-Based Fragrance
           Delivery Systems
    • Authors: Kemal Arda Günay; Daniel Benczédi, Andreas Herrmann, Harm-Anton Klok
      Abstract: Surface deposition is a critical step in the application of fragrance-containing products. This contribution presents a novel strategy to enhance the deposition of polymer-based fragrance delivery systems onto cotton substrates from the application medium using phage display identified peptides. Following the identification of cotton binding peptide ligands under fabric softening conditions via phage display, the strongest binding peptide ligand is incorporated into two model polymer-based fragrance delivery systems, viz., polymer profragrances and polymer nanoparticles. The model polymer profragrance used is a linear, water soluble poly(N-(2-hydroxypropyl)methacrylamide) conjugate, while poly(styrene-co-acrylic acid) (PS-co-PAA) nanoparticles prepared via miniemulsion polymerization are chosen as the second model system. The incorporation of the cotton binding peptide ligand into these fragrance delivery systems enhances their surface deposition two- to three-fold, as evidenced by fluorescence intensity measurements. In the case of the fragrance-containing PS-co-PAA nanoparticles, the enhanced surface deposition also translates into an increased fragrance release from the cotton surface according to dynamic headspace sampling measurements.Surface deposition is an essential step in the application of fragrance-containing products. In this work, a peptide that binds to cotton fabric under softening conditions is identified and used to enhance surface deposition of two polymer-based fragrance delivery systems. This strategy may be generalized to other delivery systems and used for a range of personal care and consumer products.
      PubDate: 2016-11-08T08:30:33.151767-05:
      DOI: 10.1002/adfm.201603843
       
  • Advanced Functional Nanomaterials for Theranostics
    • Authors: Haoyuan Huang; Jonathan F. Lovell
      Abstract: Nanoscale materials have been explored extensively as agents for therapeutic and diagnostic (i.e., theranostic) applications. Research efforts have shifted from exploring new materials in vitro to designing materials that function in more relevant animal disease models, thereby increasing potential for clinical translation. Current interests include non-invasive imaging of diseases, biomarkers, and targeted delivery of therapeutic drugs. Here, some general design considerations of advanced theranostic materials and challenges of their use, from both diagnostic and therapeutic perspectives, are discussed. Common classes of nanoscale biomaterials, including magnetic nanoparticles, quantum dots, upconversion nanoparticles, mesoporous silica nanoparticles, carbon-based nanoparticles, and organic dye-based nanoparticles, have demonstrated potential for both diagnosis and therapy. Variations such as size control and surface modifications can modulate biocompatibility and interactions with target tissues. The need for improved disease detection and enhanced chemotherapeutic treatments, together with realistic considerations for clinically translatable nanomaterials, will be key driving factors for theranostic agent research in the near future.Theranostic nanoparticles have emerged as promising materials that possess both diagnostic and therapeutic functional capabilities as versatile platform technologies. Recent approaches and common classes of materials are reviewed here.
      PubDate: 2016-11-07T08:21:24.813319-05:
      DOI: 10.1002/adfm.201603524
       
  • Real-Time Probing Nanopore-in-Nanogap Plasmonic Coupling Effect on Silver
           Supercrystals with Surface-Enhanced Raman Spectroscopy
    • Authors: Cong Ma; Qiangqiang Gao, Wei Hong, Jie Fan, Jixiang Fang
      Abstract: Nanopore structures have displayed attractive prospects in diverse important applications such as nanopore-based biosensors and enhanced spectroscopy. However, on the one hand, the fabrication techniques to obtain sub-10 nm sized nanopores so far is very limited. On the other hand, the electromagnetic enhancement of nanopores is still relatively low. In this work, using a facile chemical etching strategy on 2D plasmonic Ag nanoparticle supercrystals, fine nanopore arrays with sub-10 nm pore size have been successfully fabricated and a “nanopore-in-nanogap” hybrid plasmon mode has been investigated. An in situ etching and surface-enhanced Raman spectroscopy (SERS) detection indicate that novel hybrid plasmon structure may create an enhanced electromagnetic coupling and increase SERS signal at ≈10× magnification. The breaking of plasmon bonding dipolar mode and generation of antibonding-like plasmon mode contribute to this enhanced electromagnetic coupling. The facile etching strategy, as a common approach, may open the doors for the fabrication of nanopores in various compositions for numerous applications.Using a facile chemical etching strategy on 2D plasmonic Ag NP supercrystals, fine nanopore arrays with sub-10 nm pore size have been successfully fabricated and a “nanopore-in-nanogap” hybrid plasmon mode has been investigated. In situ etching and surface enhanced Raman spectroscopy (SERS) detection indicate that novel hybrid plasmon structure may create an enhanced electromagnetic coupling and increase the SERS signal at ≈10× magnification.
      PubDate: 2016-11-03T08:30:45.244925-05:
      DOI: 10.1002/adfm.201603233
       
  • A Novel Ultrafine Needle (UN) for Innocuous and Efficient Subcutaneous
           Insulin Delivery
    • Authors: Cheng Guo Li; Yonghao Ma, Inyoung Huh, Shayan Fakhraei Lahiji, Sang-Guk Lee, Hyungil Jung
      Abstract: Subcutaneous (SC) insulin injection has been demonstrated to be the most effective method for treatment of diabetes mellitus but is conventionally performed by hypodermic needles, leading to poor management of diabetes because of the pain, needle phobia, and tissue trauma. Identification of a viable, safe, and pain-free alternative method has been a longstanding challenge in modern health care. Here, the thermoplastic droplet stretching technique is developed to create an ultrahigh-aspect-ratio needle mold with simple microstructure control. The optimized ultrafine needle (UN) with 4 mm length, minimized 120 µm outer diameter, and 15° sharp bevel angle is formed via electroplating of a metallic layer on the surface of a needle mold with forcing sharp tip. This novel UN enables minimally invasive 4 mm skin insertion to deliver insulin in the targeted SC layer. The similar relative areas under the curves of insulin concentration within UN and 31G needle in vivo insulin administration indicate that UN can ensure stable insulin absorption for secure blood glucose management. Additionally, the proposed fabrication method may facilitate industrialization and commercialization of the UN, holding great promise for replacement of hypodermic needles and for improvement of quality of life among patients with diabetes.A new subcutaneous drug delivery system, ultrafine needle (UN), is invented to perform innocuous and efficient subcutaneous insulin injection. The optimized UN can be obtained directly via a thermoplastic droplet stretching technique with controlled shape. The smaller tissue damage and highly accurate and reproducible subcutaneous insulin delivery via the UN show great potential for the improvement of diabetics' quality of life.
      PubDate: 2016-11-03T07:46:33.112571-05:
      DOI: 10.1002/adfm.201603228
       
  • Electrospun Photocrosslinkable Hydrogel Fibrous Scaffolds for Rapid In
           Vivo Vascularized Skin Flap Regeneration
    • Authors: Xiaoming Sun; Qi Lang, Hongbo Zhang, Liying Cheng, Ying Zhang, Guoqing Pan, Xin Zhao, Huilin Yang, Yuguang Zhang, Hélder A. Santos, Wenguo Cui
      Abstract: Distal necrosis of random skin flap is always clinical problematic in plastic surgery. The development of 3D functional vascular networks is fundamental for the survival of a local random skin flap. Herein, an effective technique on constructing 3D fibrous scaffolds for accelerated vascularization is demonstrated using a photocrosslinkable natural hydrogel based on gelatin methacryloyl (GelMA) by electrospinning. It is found that the ultraviolet (UV) photocrosslinkable gelatin electrospun hydrogel fibrous membranes exhibit soft adjustable mechanical properties and controllable degradation properties. Furthermore, it is observed that the optimized hydrogel scaffolds can support endothelial cells and dermal fibroblasts adhesion, proliferation, and migration into the scaffolds, which facilitates vascularization. Importantly, a rapid formation of tubes is observed after 3 d seeding of endothelial cells. After GelMA fibrous scaffold implantation below the skin flap in a rat model, it is found that the flap survival rate is higher than the control group, and there is more microvascular formation, which is potentially beneficial for the flap tissue vascularization. These data suggest that GelMA hydrogels can be used for biomedical applications that require the formation of microvascular networks, including the development of complex engineered tissues.An electrospun hydrogel fibrous scaffold based on photocrosslinkable gelatin for accelerating vascularization is reported. The scaffold exhibits not only hydrogel properties but also maintains 3D spatial structure, which greatly stimulates 3D cells growth and subsequent vascularization process. Comparing to the conventional hydrogel, the hydrogel fibrous scaffold is very promising for repairing random skin flaps.
      PubDate: 2016-11-02T08:06:20.542898-05:
      DOI: 10.1002/adfm.201604617
       
  • Carbonized Cotton Fabric for High-Performance Wearable Strain Sensors
    • Authors: Mingchao Zhang; Chunya Wang, Huimin Wang, Muqiang Jian, Xiangyang Hao, Yingying Zhang
      Abstract: Recent years have witnessed the booming development of flexible strain sensors. To date, it is still a great challenge to fabricate strain sensors with both large workable strain range and high sensitivity. Cotton is an abundant supplied natural material composed of cellulose fibers and has been widely used for textiles and clothing. In this work, the fabrication of highly sensitive wearable strain sensors based on commercial plain weave cotton fabric, which is the most popular fabric for clothes, is demonstrated through a low-cost and scalable process. The strain sensors based on carbonized cotton fabric exhibit fascinating performance, including large workable strain range (>140%), superior sensitivity (gauge factor of 25 in strain of 0%–80% and that of 64 in strain of 80%–140%), inconspicuous drift, and long-term stability, simultaneously offering advantages of low cost and simplicity in device fabrication and versatility in applications. Notably, the strain sensor can detect a subtle strain of as low as 0.02%. Based on its superior performance, its applications in monitoring both vigorous and subtle human motions are demonstrated, showing its tremendous potential for applications in wearable electronics and intelligent robots.Based on carbonized plain weave cotton fabric, a wearable strain sensor with high sensitivity and large workable strain range (up to 140%) is fabricated through a cost-effective, scalable, and green process. Its working mechanism is investigated and its application in detection of both subtle and large deformation of the human body is demonstrated, promising great potential in wearable electronics.
      PubDate: 2016-11-02T08:02:01.433792-05:
      DOI: 10.1002/adfm.201604795
       
  • Rational Design of High-Mobility Semicrystalline Conjugated Polymers with
           Tunable Charge Polarity: Beyond Benzobisthiadiazole-Based Polymers
    • Authors: Yang Wang; Tsukasa Hasegawa, Hidetoshi Matsumoto, Takehiko Mori, Tsuyoshi Michinobu
      Abstract: High-mobility semiconducting polymers composed of arylene vinylene and dithiophene-thiadiazolobenzotriazole (SN) units are developed by three powerful design strategies, namely, backbone engineering, heteroatom substitution, and side-chain engineering. First, starting from the quaterthiophene-SN copolymer, a vinylene spacer is inserted into the quaterthiophene unit for constructing highly-planar backbones. Second, heteroatoms (O and N atoms) are incorporated into the thienylene vinylene moieties to tune the electronic properties and intermolecular interactions. Third, the alkyl side chains are optimized to tune the solubility and self-assembly properties. As a consequence, a remarkable thin film transistor performance is obtained. The very high hole mobility of 3.22 cm2 V−1 s−1 is achieved for the p-type polymer, PSNVT-DTC8, which is the highest value ever reported for the polymers based on the benzobisthiadiazole and its analogs. Moreover, heteroatom substitution efficiently varies the charge polarity of the polymers as in the case of the N atom substituted PSNVTz-DTC16 displaying n-type dominant ambipolar properties with the electron mobility of 0.16 cm2 V−1 s−1. Further studies using grazing-incidence wide-angle X-ray scattering and atomic force microscopy have revealed the high crystallinities of the polymer thin films with strong π–π interactions and suitable polymer packing orientations.An effective design strategy for producing superior semiconducting polymers is proposed. By employing this strategy, a field-effect hole mobility as high as 3.22 cm2 V−1 s−1 is achieved in the conventional top contact/bottom gate transistor based on one of the newly synthesized polymers. This value is the highest among all the reported polymers containing benzobisthiadiazole and its analogs.
      PubDate: 2016-10-28T08:46:16.625882-05:
      DOI: 10.1002/adfm.201604608
       
  • Osmotic Power Generation with Positively and Negatively Charged 2D
           Nanofluidic Membrane Pairs
    • Authors: Jinzhao Ji; Qian Kang, Yi Zhou, Yaping Feng, Xi Chen, Jinying Yuan, Wei Guo, Yen Wei, Lei Jiang
      Abstract: In nature, hierarchically assembled nanoscale ionic conductors, such as ion channels and ion pumps, become the structural and functional basis of bioelectric phenomena. Recently, ion-channel-mimetic nanofluidic systems have been built into reconstructed 2D nanomaterials for energy conversion and storage as effective as the electrogenic cells. Here, a 2D-material-based nanofluidic reverse electrodialysis system, containing cascading lamellar nanochannels in oppositely charged graphene oxide membrane (GOM) pairs, is reported for efficient osmotic energy conversion. Through preassembly modification, the surface charge polarity of the 2D nanochannels can be efficiently tuned from negative (−123 mC m−2) to positive (+147 mC m−2), yielding strongly cation- or anion-selective GOMs. The complementary two-way ion diffusion leads to an efficient charge separation process, creating superposed electrochemical potential difference and ionic flux. An output power density of 0.77 W m−2 is achieved by controlled mixing concentrated (0.5 m) and diluted ionic solutions (0.01 m), which is about 54% higher than using commercial ion exchange membranes. Tandem alternating GOM pairs produce high voltage up to 2.7 V to power electronic devices. Besides simple salt solutions, various complex electrolyte solutions can be used as energy sources. These findings provide insights to construct cascading nanofluidic circuits for energy, environmental, and healthcare applications.2D-material-based high-performance osmotic energy conversion from complex ionic solutions is achieved with chemically modified, oppositely charged graphene oxide membrane (GOM) pairs. The output power density approaches 0.77 W m−2, which is 54% higher than using commercial ion-exchange membranes. Tandem GOM stacks produce high voltages up to 2.7 V to power real electronic devices. The bio-inspired 2D nanofluidic materials anticipate substantial advance in membrane-based technologies for energy, environmental, and healthcare applications.
      PubDate: 2016-10-28T07:02:44.770824-05:
      DOI: 10.1002/adfm.201603623
       
  • A Synergetic Effect of Molecular Weight and Fluorine in All-Polymer Solar
           Cells with Enhanced Performance
    • Authors: Shanshan Chen; Yujin An, Gitish K. Dutta, Yiho Kim, Zhi-Guo Zhang, Yongfang Li, Changduk Yang
      Abstract: A synergetic effect of molecular weight (Mn) and fluorine (F) on the performance of all-polymer solar cells (all-PSCs) is comprehensively investigated by tuning the Mn of the acceptor polymer poly((N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl)-alt-5,5′-(2,2′-bithiophene)) (P(NDI2OD-T2)) and the F content of donor polymer poly(2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-dyl-alt-thiophene-2,5-diyl). Both Mn and F variations strongly influence the charge transport properties and morphology of the blend films, which have a significant impact on the photovoltaic performance of all-PSCs. In particular, the effectiveness of high Mn in increasing power conversion efficiency (PCE) can be greatly improved by the devices based on optimum F content, reaching a PCE of 7.31% from the best all-PSC combination. These findings enable us to further understand the working principles of all-PSCs with a view on achieving even higher power conversion efficiency in the future.To establish a correlation between the effects of molecular weight (Mn) and fluorine (F) on photovoltaic performance, all-polymer solar cells have been comprehensively investigated based on donor polymers of TQ family with various F content and P(NDI2OD-T2) acceptor polymers with various Mn. An efficiency of 7.31% is demonstrated by blending the optimum F content-containing donor with a high Mn acceptor.
      PubDate: 2016-10-28T07:02:10.905102-05:
      DOI: 10.1002/adfm.201603564
       
  • Spin Crossover of Yb2+ in CsCaX3 and CsSrX3 (X = Cl, Br, I) – A
           Guideline to Novel Halide-Based Scintillators
    • Authors: Markus Suta; Claudia Wickleder
      Abstract: In this paper, the temperature dependence of the photoluminescence of Yb2+ doped into the halidoperovskites CsMX3 (M = Ca, Sr; X = Cl, Br, I) is presented. Yb2+ shows spin-forbidden high-spin (HS) and spin-allowed low-spin (LS) emission bands in all compounds. Upon excitation of the higher energetic LS transition, very different behaviors of the interplay of the two emissive transitions are observed. In the chlorides, the HS-based emission becomes already dominant at higher temperatures than 50 K; in the bromides, a temperature-dependent population of the HS state is observed at higher temperatures than 200 K, whereas in the iodides, the LS emission remains dominant even above 300 K. A vibrational relaxation model is attempted for the explanation of this behavior that reveals a very delicate dependence on the mode energies of the [YbX6]4− octahedra. FIR spectra of the pure Yb2+-based compounds CsYbX3 are also presented to experimentally verify the estimated average mode energies from the model. Finally, the relevance for novel Yb2+-based scintillators is discussed.In this paper, the thermally induced spin crossover of Yb2+ in the halidoperovskites CsCaX3 and CsSrX3 (X = Cl, Br, I) is analyzed. It is shown that there is a delicate dependence of the luminescence intensities of the spin-forbidden and spin-allowed emission upon the vibrational energies of the [YbX6]4− moieties. This may be important for the design of novel Yb2+-based scintillators.
      PubDate: 2016-10-26T09:20:38.068567-05:
      DOI: 10.1002/adfm.201602783
       
 
 
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