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  Subjects -> CHEMISTRY (Total: 846 journals)
    - ANALYTICAL CHEMISTRY (47 journals)
    - CHEMISTRY (597 journals)
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CHEMISTRY (597 journals)                  1 2 3 | 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: 26)
ACS Catalysis     Full-text available via subscription   (Followers: 23)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 15)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 24)
ACS Macro Letters     Full-text available via subscription   (Followers: 18)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 31)
ACS Nano     Full-text available via subscription   (Followers: 156)
ACS Photonics     Full-text available via subscription   (Followers: 6)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 16)
Acta Chemica Iasi     Open Access  
Acta Chimica Sinica     Full-text available via subscription   (Followers: 1)
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 4)
Acta Scientifica Naturalis     Open Access  
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 5)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 4)
Advanced Functional Materials     Hybrid Journal   (Followers: 41)
Advanced Science Focus     Free   (Followers: 2)
Advances in Chemical Engineering and Science     Open Access   (Followers: 33)
Advances in Chemical Science     Open Access   (Followers: 10)
Advances in Chemistry     Open Access   (Followers: 7)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 14)
Advances in Drug Research     Full-text available via subscription   (Followers: 21)
Advances in Environmental Chemistry     Open Access   (Followers: 1)
Advances in Enzyme Research     Open Access   (Followers: 4)
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: 15)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 36)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 13)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 13)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 2)
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: 6)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
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: 68)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 12)
American Journal of Chemistry     Open Access   (Followers: 23)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Full-text available via subscription   (Followers: 7)
Anadolu University Journal of Science and Technology     Open Access  
Analyst     Full-text available via subscription   (Followers: 41)
Angewandte Chemie     Hybrid Journal   (Followers: 115)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 163)
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: 2)
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: 8)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 13)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Full-text available via subscription  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 5)
Applied Spectroscopy     Full-text available via subscription   (Followers: 22)
Applied Surface Science     Hybrid Journal   (Followers: 20)
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: 2)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 4)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 8)
Biochemistry     Full-text available via subscription   (Followers: 203)
Biochemistry Insights     Open Access   (Followers: 4)
Biochemistry Research International     Open Access   (Followers: 4)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 8)
Bioinspired Materials     Open Access   (Followers: 2)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 1)
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: 9)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 2)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 94)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 86)
Bioorganic Chemistry     Hybrid Journal   (Followers: 9)
Biopolymers     Hybrid Journal   (Followers: 16)
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: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal  
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: 6)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 27)
Carbon     Hybrid Journal   (Followers: 64)
Catalysis for Sustainable Energy     Open Access   (Followers: 4)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 6)
Catalysis Science and Technology     Free   (Followers: 4)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 5)
Cellulose     Hybrid Journal   (Followers: 4)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription  
ChemCatChem     Hybrid Journal   (Followers: 5)
Chemical and Engineering News     Free   (Followers: 10)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 62)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 20)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 17)
Chemical Reviews     Full-text available via subscription   (Followers: 137)
Chemical Science     Open Access   (Followers: 18)
Chemical Technology     Open Access   (Followers: 5)
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: 26)
ChemInform     Hybrid Journal   (Followers: 4)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 2)
Chemistry - A European Journal     Hybrid Journal   (Followers: 109)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 12)
Chemistry and Materials Research     Open Access   (Followers: 14)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry Education Research and Practice     Free   (Followers: 4)
Chemistry in Education     Open Access   (Followers: 2)
Chemistry International     Hybrid Journal   (Followers: 1)
Chemistry Letters     Full-text available via subscription   (Followers: 41)
Chemistry of Materials     Full-text available via subscription   (Followers: 137)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 8)
Chemistry World     Full-text available via subscription   (Followers: 21)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 1)
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: 6)
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: 25)
Chromatography     Open Access   (Followers: 5)
Chromatography Research International     Open Access   (Followers: 5)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 8)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 17)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Composite Interfaces     Hybrid Journal   (Followers: 3)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 1)
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: 10)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 10)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
Coordination Chemistry Reviews     Full-text available via subscription  
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 4)
Crystal Structure Theory and Applications     Open Access   (Followers: 2)
CrystEngComm     Full-text available via subscription   (Followers: 6)
Current Catalysis     Hybrid Journal   (Followers: 1)
Current Metabolomics     Hybrid Journal   (Followers: 3)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 7)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 16)
Current Research in Chemistry     Open Access   (Followers: 7)
Current Science     Open Access   (Followers: 11)
Dalton Transactions     Full-text available via subscription   (Followers: 17)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 1)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 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: 4)
Elements     Full-text available via subscription  
Environmental Chemistry     Hybrid Journal   (Followers: 5)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 2)

        1 2 3 | Last

Journal Cover Advanced Functional Materials
  [SJR: 4.682]   [H-I: 156]   [41 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  [1598 journals]
  • Masthead: (Adv. Funct. Mater. 23/2016)
    • PubDate: 2016-06-20T09:38:02.761359-05:
      DOI: 10.1002/adfm.201670145
       
  • Biomechanical Cell Regulation by High Aspect Ratio Nanoimprinted Pillars
    • Abstract: High aspect ratio pillared topographies provide a large number of mechanical cues that cells can sense and react to. High aspect ratio pillars have been employed effectively to promote stem cell differentiation and to probe cellular tractions. Yet, the full potential of these topographies for mechanobiology remains insufficiently characterized. Here, the response of progenitor neural stem cells to dense high aspect ratio polymer pillars in the nano‐ and microscale is investigated. Thermal nanoimprinting is utilized to fabricate with high precision well‐defined pillars with high density and aspect ratio. Studies on cell viability, morphology, cell spreading, and migration are performed comparatively to a control flat substrate. The traction forces exerted by the cells on the pillar structures are probed quantitatively by a combined focused ion beam scanning electron microscopy (FIB‐SEM) technique. The cell responses observed are distinctive for each dimension, following the trend that an increase in aspect ratio and feature size from nano‐ to micronscale results in more confined cell morphology with large cytoplasmic penetrations and nuclear deformation. Accordingly, cells seeded on the micrometer scale topography show reduced mobility, a persistent quasi‐directional migration, high traction forces, and a lower rate of proliferation. Cells on the nanotopography show higher rate of proliferation, a large cell spread, high mobility with random migration altogether with lower traction forces. The response of progenitor neural stem cells to dense high aspect ratio polymer pillars on the nano‐ and microscale is investigated. Cells on the nanotopography show large cell spread area, high random migration dynamics, and high traction forces. Cells on the microtopography show a confined cell spread with large topographical insertions, persistent quasi‐directional migration, and large traction forces.
      PubDate: 2016-06-20T09:31:22.723467-05:
      DOI: 10.1002/adfm.201601817
       
  • Triplet Energy Transfer from PbS(Se) Nanocrystals to Rubrene: the
           Relationship between the Upconversion Quantum Yield and Size
    • Authors: Melika Mahboub; Hadi Maghsoudiganjeh, Andrew Minh Pham, Zhiyuan Huang, Ming Lee Tang
      Abstract: Photon upconversion has attracted enormous attention due to its wide range of applications in biological imaging, photocatalysis, and especially photovoltaics. Here, the effect of quantum confinement on the efficiency of Dexter energy transfer from PbS and PbSe nanocrystals (NCs) to a rubrene acceptor is studied. A series of experiments exploring the relationship between NC size and the upconversion quantum yield (QY) in this hybrid platform show that energy transfer occurs in the Marcus normal regime. By decreasing the NC diameter from 3.5 to 2.9 nm for PbS and from 3.2 to 2.5 nm for PbSe, the relative upconversion QY is enhanced about 700 and 250‐fold respectively. In addition, the dynamic Stern–Volmer constant (KSV) for the quenching of PbSe NCs by rubrene increases approximately fivefold with a decrease in NC diameter from 3.2 to 2.5 nm to a value of 200 m−1. This work shows that high quality, well‐passivated, small NCs are critical for efficient triplet energy transfer to molecular acceptors. Small lead chalcogenide nanocrystals (NCs) result in more efficient upconversion of near infrared light to visible light. In this hybrid platform, PbS and PbSe NCs are used as the light absorbers that transfer energy to a molecular emitter, in this case rubrene. This hybrid upconversion platform has great potential for use in solar energy conversion, photocatalysis, and bioimaging.
      PubDate: 2016-06-20T06:21:08.493404-05:
      DOI: 10.1002/adfm.201505623
       
  • Enhanced Stability of Perovskite Solar Cells with Low‐Temperature
           Hydrothermally Grown SnO2 Electron Transport Layers
    • Abstract: Perovskite solar cells (PSCs) may offer huge potential in photovoltaic conversion, yet their practical applications face one major obstacle: their low stability, or quick degradation of their initial efficiencies. Here, a new design scheme is presented to enhance the PSC stability by using low‐temperature hydrothermally grown hierarchical nano‐SnO2 electron transport layers (ETLs). The ETL contains a thin compact SnO2 layer underneath a mesoporous layer of SnO2 nanosheets. The mesoporous layer plays multiple roles of enhancing photon collection, preventing moisture penetration and improving the long‐term stability. Through such simple approaches, PSCs with power conversion efficiencies of ≈13% can be readily obtained, with the highest efficiency to be 16.17%. A prototypical PSC preserves 90% of its initial efficiency even after storage in air at room temperature for 130 d without encapsulation. This study demonstrates that hierarchical SnO2 is a potential ETL for fabricating low‐cost and efficient PSCs with long‐term stability. Low‐temperature hydrothermally grown hierarchical SnO2 , a mesoporous layer of nanosheet arrays on a compact nanoparticle layer, is used as the electron transporting layer to enhance the long‐term stability of perovskite solar cells. A mesoporous device preserves 90% of its initial efficiency, even after storage in air for 130 d without encapsulation.
      PubDate: 2016-06-20T06:21:04.019137-05:
      DOI: 10.1002/adfm.201600910
       
  • Impact of the Nature of the Side‐Chains on the
           Polymer‐Fullerene Packing in the Mixed Regions of Bulk
           Heterojunction Solar Cells
    • Abstract: Polymer‐fullerene packing in mixed regions of a bulk heterojunction solar cell is expected to play a major role in exciton‐dissociation, charge‐separation, and charge‐recombination processes. Here, molecular dynamics simulations are combined with density functional theory calculations to examine the impact of nature and location of polymer side‐chains on the polymer‐fullerene packing in mixed regions. The focus is on poly‐benzo[1,2‐b:4,5‐b′]dithiophene‐thieno[3,4‐c]pyrrole‐4,6‐dione (PBDTTPD) as electron‐donating material and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) as electron‐accepting material. Three polymer side‐chain patterns are considered: i) linear side‐chains on both benzodithiophene (BDT) and thienopyrroledione (TPD) moieties; ii) two linear side‐chains on BDT and a branched side‐chain on TPD; and iii) two branched side‐chains on BDT and a linear side‐chain on TPD. Increasing the number of branched side‐chains is found to decrease the polymer packing density and thereby to enhance PBDTTPD–PC61 BM mixing. The nature and location of side‐chains are found to play a determining role in the probability of finding PC61BM molecules close to either BDT or TPD. The electronic couplings relevant for the exciton‐dissociation and charge‐recombination processes are also evaluated. Overall, the findings are consistent with the experimental evolution of the PBDTTPD–PC61BM solar‐cell performance as a function of side‐chain patterns. Polymer side‐chains are expected to play a significant role in determining the polymer‐fullerene packing in the mixed regions of bulk‐heterojunction solar cells. The computational work, based on a combination of molecular dynamics simulations and density functional theory calculations, provides a detailed description of the impact that the nature and locations of the polymer side‐chains have on the nanoscale polymer‐fullerene packing.
      PubDate: 2016-06-20T06:20:58.168175-05:
      DOI: 10.1002/adfm.201601134
       
  • State‐of‐the‐Art Neutral Tint Multichromophoric Polymers
           for High‐Contrast See‐Through Electrochromic Devices
    • Authors: Mauro Sassi; Matteo M. Salamone, Riccardo Ruffo, Giorgio E. Patriarca, Claudio M. Mari, Giorgio A. Pagani, Uwe Posset, Luca Beverina
      Abstract: Two new multichromophoric electrochromic polymers featuring a conjugated EDOT/ProDOT copolymer backbone (PXDOT) and a reversible Weitz‐type redox active small molecule electrochrome (WTE) tethered to the conjugated chain are reported here. The careful design of the WTEs provides a highly reversible redox behavior with a colorless red switching that complements the colorless blue switching of the conjugated backbone. Subtractive color mixing successfully provides high performing solution processable polymeric layers with colorless neutral tint switchable limiting states for application in see‐through electrochromic devices. Design, synthesis, comprehensive chemical and spectroelectrochemical characterization as well as the preparation of a proof‐of‐concept device are discussed. The side chain functionalization of an original, in situ polymerized PEDOT with Weitz‐type small molecule electrochromic derivatives provides an excellent solution processable material for neutral tint switchable eyewear. Design, synthesis, comprehensive chemical, and spectroelectrochemical characterization as well as the preparation of exclusively solution‐processed devices are discussed.
      PubDate: 2016-06-20T06:20:51.029462-05:
      DOI: 10.1002/adfm.201601819
       
  • High‐Sensitivity Floating‐Gate Phototransistors Based on WS2
           and MoS2
    • Authors: Fan Gong; Wenjin Luo, Jianlu Wang, Peng Wang, Hehai Fang, Dingshan Zheng, Nan Guo, Jingli Wang, Man Luo, Johnny C. Ho, Xiaoshuang Chen, Wei Lu, Lei Liao, Weida Hu
      Abstract: In recent years, 2D layered materials have been considered as promising photon absorption channel media for next‐generation phototransistors due to their atomic thickness, easily tailored single‐crystal van der Waals heterostructures, ultrafast optoelectronic characteristics, and broadband photon absorption. However, the photosensitivity obtained from such devices, even under a large bias voltage, is still unsatisfactory until now. In this paper, high‐sensitivity phototransistors based on WS2 and MoS2 are proposed, designed, and fabricated with gold nanoparticles (AuNPs) embedded in the gate dielectric. These AuNPs, located between the tunneling and blocking dielectric, are found to enable efficient electron trapping in order to strongly suppress dark current. Ultralow dark current (10−11 A), high photoresponsivity (1090 A W−1), and high detectivity (3.5 × 1011 Jones) are obtained for the WS2 devices under a low source/drain and a zero gate voltage at a wavelength of 520 nm. These results demonstrate that the floating‐gate memory structure is an effective configuration to achieve high‐performance 2D electronic/optoelectronic devices. This study reports a novel float‐gated memory structure phototransistor based on multilayer WS2 with gold nanoparticles embedded in the gate dielectric. The device represents excellent photodetection capabilities demonstrating that the float‐gated memory is an effective configuration to achieve high‐performance 2D optoelectronic devices.
      PubDate: 2016-06-20T06:20:47.076459-05:
      DOI: 10.1002/adfm.201601346
       
  • Fullerene‐Free Polymer Solar Cells with Open‐Circuit Voltage
           above 1.2 V: Tuning Phase Separation Behavior with Oligomer to Replace
           Polymer Acceptor
    • Authors: Yingying Fu; Bei Wang, Jianfei Qu, Yang Wu, Wei Ma, Yanhou Geng, Yanchun Han, Zhiyuan Xie
      Abstract: This study has proposed to use a well‐defined oligomer F4TBT4 to replace its analogue polymer as electron acceptor toward tuning the phase separation behavior and enhancing the photovoltaic performance of all‐polymer solar cells. It has been disclosed that the oligomer acceptor favors to construct pure and large‐scale phase separation in the polymer:oligomer blend film in contrast to the polymer:polymer blend film. This gets benefit from the well‐defined structure and short rigid conformation of the oligomer that endows it aggregation capability and avoids possible entanglement with the polymer donor chains. The charge recombination is to some extent suppressed and charge extraction is also improved. Finally, the P3HT:F4TBT4 solar cells not only output a high VOC above 1.2 V, but also achieve a power conversion efficiency of 4.12%, which is two times higher than the P3HT:PFTBT solar cells and is comparable to the P3HT:PCBM solar cells. The strategy of constructing optimum phase separation with oligomer to replace polymer opens up new prospect for the further improvement of the all‐polymer solar cells. A well‐defined oligomer F4TBT4 is proposed to replace its polymer PFTBT as electron acceptor to fabricate fullerene‐free polymer solar cells. The oligomer acceptor favors to construct pure and large‐scale phase separation in polymer blend film due to decreased chain entanglement. The resulted P3HT:F4TBT4 solar cells not only output a high VOC above 1.2 V, but also achieve a PCE of 4.12%.
      PubDate: 2016-06-17T10:46:23.33398-05:0
      DOI: 10.1002/adfm.201601880
       
  • Metal Oxide Transistors via Polyethylenimine Doping of the Channel Layer:
           Interplay of Doping, Microstructure, and Charge Transport
    • Authors: Wei Huang; Li Zeng, Xinge Yu, Peijun Guo, Binghao Wang, Qing Ma, Robert P. H. Chang, Junsheng Yu, Michael J. Bedzyk, Tobin J. Marks, Antonio Facchetti
      Abstract: Polymer doping of solution‐processed In2O3 with small amounts of the electron‐rich polymer, polyethylenimine (PEI), affords superior transistor performance, including higher electron mobility than that of the pristine In2O3 matrix. PEI doping of In2O3 films not only frustrates crystallization and controls the carrier concentration but, more importantly, acts as electron dopant and/or scattering center depending on the polymer doping concentration. The electron donating capacity of PEI combined with charge trapping and variation in the matrix film microstructure yields, for optimum PEI doping concentrations of 1.0%–1.5%, electron mobilities as high as ≈9 cm2 V−1 s−1 on a 300 nm SiO2 gate dielectric, an excellent on/off ratio of ≈107, and an application optimal V T. Importantly, these metrics exceed those of the pure In2O3 matrix with a maximum mobility ≈4 cm2 V−1 s−1. Furthermore, we show that this approach is extendible to other oxide compositions such as IZO and the technologically relevant IGZO. This work opens a new means to fabricate amorphous semiconductors via solution processing at low temperatures, while preserving or enhancing the mobility of the pristine polycrystalline semiconductor. Enhanced metal oxide (In2O3, IZO, IGZO) transistor performance via polyethylenimine (PEI) doping is demonstrated for the first time. Unlike previous doping methods for metal oxides, PEI doping not only effectively frustrates crystallization and controls the carrier concentration but also increases the electron mobility of the metal oxide matrix. The PEI electron donating capacity combined with charge trapping and variation in the matrix film microstructure result, for proper PEI doping levels, in high electron mobility and optimal TFT off‐currents and threshold voltages.
      PubDate: 2016-06-17T10:46:10.94573-05:0
      DOI: 10.1002/adfm.201602069
       
  • “To Catch or Not to Catch”: Microcapsule‐Based Sandwich
           Assay for Detection of Proteins and Nucleic Acids
    • Authors: Sujit K. Verma; Amanda Amoah, Ulla Schellhaas, Mathias Winterhalter, Sebastian Springer, Tatiana A. Kolesnikova
      Abstract: The development of new assays that specifically detect intermediate or final products of biotechnological processes or multiple analytes in biomedical research is important for diagnostics and biotechnology. This study presents a microcapsule‐based sandwich assay for detection of proteins and nucleic acids using flow cytometry as an optical readout. The main component of the assay are robust chemically cross‐linked microcapsules that are coated with adaptor proteins such as protein A or streptavidin. In the first approach, the ability of detecting the blood cancer biomarker beta‐2 microglobulin in the fM to pM concentration range with the help of protein A‐coated capsules is demonstrated. In the second approach, streptavidin‐coated capsules are used for detection of nucleic acids in the nM concentration range. The developed assay allows rapid quantitative analyte measurement, while providing high sensitivity and selectivity at very small sample quantities. In the future, protein A‐ and streptavidin‐coated microcapsules can be used as universal tools for detection of a broad range of analytes. The development of a microcapsule‐based assay for detection of proteins and nucleic acids using flow cytometry as an optical readout is described. (PAH/PAA)2 capsules are chemically cross‐linked and coated with protein A or streptavidin, which allow capturing antibodies or biotinylated molecules in optimized orientation. The detection is performed on the capsule surface, when the analyte is sandwiched between a binder and a detector molecule. The assay sensitivity and selectivity are verified using the biomarker protein human beta‐2 microglobulin and small oligonucleotide molecules as analytes.
      PubDate: 2016-06-16T09:20:42.717846-05:
      DOI: 10.1002/adfm.201601328
       
  • Healing All‐Inorganic Perovskite Films via Recyclable
           Dissolution–Recyrstallization for Compact and Smooth Carrier
           Channels of Optoelectronic Devices with High Stability
    • Authors: Xiaoming Li; Dejian Yu, Fei Cao, Yu Gu, Yi Wei, Ye Wu, Jizhong Song, Haibo Zeng
      Abstract: The strong ionic character endows all‐inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (NCs) with different chemical features from classical Cd‐based NCs, especially when considering their interaction with polar solvents and surfactants. This has aroused intensive interest, but is still short of comprehensive understanding. More significantly, above characteristic may be used to improve the quality of perovskite thin films, which is crucial for the carrier transport inside optoelectronic devices. Here, an interesting recyclable dissolution–recyrstallization phenomenon of all‐inorganic pervoskite, as well as its application on room temperature (RT) self‐healing of compact and smooth carrier channels in ambient atmosphere for high‐performance PDs with high stability is reported. First, according to solubility equilibrium principle, the size of CsPbBr3 crystals can be reversibly tuned in the range of 10 nm–1 μm through washing with polar solvent or stirring with assistance of surfactants at RT. Second, such phenomenon is applied for significant film quality improvement by forming a liquid circumstance within films, which can transport matter at surface and sharp parts into the gaps, healing themselves at RT. This strategy results in large‐area, crack‐free, low‐roughness perovskite thin films. Obviously, such improvement facilitates transport and extraction of carriers in the channels of devices, which has been evidenced by the improvement of performances of the corresponding PDs at ambient condition. An interesting surface chemical phenomenon of all‐inorganic perovskite—recyclable dissolution and recrystallization—is reported, which is applied to build compact and smooth carrier channels for optoelectronic devices via self‐healing under ambient condition. The advantages of this film treating strategy are convinced by the improved responsivity, external quantum efficiency, response speed, and stability of photodetectors.
      PubDate: 2016-06-14T05:41:06.086327-05:
      DOI: 10.1002/adfm.201601571
       
  • Anion Acceptors Dioxaborinane Contained in Solid State Polymer
           Electrolyte: Preparation, Characterization, and DFT Calculations
    • Authors: Ping Yuan; Chuanlin Cai, Jiayong Tang, Yuqi Qin, Mengyuan Jin, Yanbao Fu, Zhenhua Li, Xiaohua Ma
      Abstract: A novel dioxaborinane‐contained solid state polymer electrolyte poly((2‐phenyl‐1, 3, 2‐dioxaborolane‐4‐yl) methyl methacrylate) (P(GMMA‐PBA)) for symmetrical capacitors (SCs) is prepared through solution casting technique. Due to the effect of electron withdrawing of dioxaborinane groups and irregular distributed porous microstructures, the solid polymer electrolyte (SPE) exhibits an optimal ionic conductivity of 0.5 mS cm−1 at ambient conditions. The electronic properties of dioxaborinane groups and their interaction with anions of electrolyte salts are further studied with density functional theory calculations. SCs fabricated with this polymer film as electrolyte and reduced graphene oxide as electrodes provide a broad potential window of 2.5 V. The energy density of this capacitor ups to 22.49 Wh kg−1 with a power density of 6.34 kW kg−1 at 5 A g−1. After 3000 charge–discharge cycles, the capacitance of the symmetrical SPE capacitor maintains 90% of its initial values. Dioxaborinane‐contained polymer electrolytes are successfully prepared for supercapacitors through solution casting technique. Density functional theory calculations are conducted by electronic structure, basis set superposition error and natural bond orbital analyses to confirm the effect of coordination between heterocyclic borane groups and perchlorate ion. The obtained anion receptor polymer electrolytes present higher electrochemical properties compared to polyethylene oxide‐based electrochemical storage capacitors.
      PubDate: 2016-06-14T05:20:35.352403-05:
      DOI: 10.1002/adfm.201600888
       
  • Bioengineered Extracellular Membranous Nanovesicles for Efficient
           Small‐Interfering RNA Delivery: Versatile Platforms for Stem Cell
           Engineering and In Vivo Delivery
    • Abstract: Naturally derived nanovesicles secreted from various cell types and found in body fluids can provide effective platforms for the delivery of various cargoes because of their intrinsic ability to be internalized for intercellular signal transmission and membrane recycling. In this study, the versatility of bioengineered extracellular membranous nanovesicles as potent carriers of small‐interfering RNAs (siRNAs) for stem cell engineering and in vivo delivery has been explored. Here, exosomes have been engineered, one of the cell‐derived vesicle types, to overexpress exosomal proteins fused with cell‐adhesion or cell‐penetrating peptides for enhanced intracellular gene transfer. To devise a more effective delivery system with potential for mass production, a new siRNA delivery system has also been developed by artificially inducing the outward budding of plasma membrane nanovesicles. Those nanovesicles have been engineered by overexpressing E‐cadherin to facilitate siRNA delivery to human stem cells with resistance to intracellular gene transfer. Both types of engineered nanovesicles deliver siRNAs to human stem cells for lineage specification with negligible cytotoxicity. The nanovesicles are efficient in delivering siRNA in vivo, suggesting feasibility for gene therapy. Cell‐derived, bioengineered nanovesicles used for siRNA delivery can provide functional platforms enabling effective stem cell therapeutics and in vivo gene therapy. The two types of cell‐derived, bioengineered nanovesicles are explored as versatile small‐interfering RNA (siRNA) delivery carriers for stem cell engineering and in vivo delivery. These siRNA delivery systems inspired by their intrinsic role in gene transfer are demonstrated to be highly efficient in guiding lineage specification of human stem cells with negligible cytotoxicity in vitro and are efficient in delivery of siRNA in vivo with marginal hepatotoxicity.
      PubDate: 2016-06-14T01:21:15.882816-05:
      DOI: 10.1002/adfm.201601430
       
  • A Scalable Free‐Standing V2O5/CNT Film Electrode for Supercapacitors
           with a Wide Operation Voltage (1.6 V) in an Aqueous Electrolyte
    • Authors: Jiabin Wu; Xiang Gao, Huimin Yu, Tianpeng Ding, Yixin Yan, Bin Yao, Xu Yao, Dongchang Chen, Meilin Liu, Liang Huang
      Abstract: While vanadium oxides have many attractive pseudocapacitive features for energy storage, their applications are severely limited by the poor electronic conductivity and low specific surface area. To overcome these limitations, a scalable, free‐standing film electrode composed of intertwined V2O5 nanowires and carbon nanotubes (CNTs) using a blade coating process has been prepared. The unique architecture of this hybrid electrode greatly facilitates electronic transport along CNTs while maintaining rapid ion diffusion within V2O5 nanowires and fast electron transfer across the V2O5/CNTs interfaces. When tested in a neutral aqueous electrolyte, this hybrid film electrode demonstrates a volumetric capacitance of ≈460 F cm−3. Moreover, a symmetric capacitor based on two identical film electrodes displays a wide operation voltage window of 1.6 V, delivering a volumetric energy density as high as 41 Wh L−1. A scalable free‐standing V2O5/carbon nanotube film is prepared through blade coating process. This film has demonstrated great electrochemical performance with a volumetric capacitance around 460 F cm−3.
      PubDate: 2016-06-14T01:21:08.005747-05:
      DOI: 10.1002/adfm.201601811
       
  • Multi‐Material Tissue Engineering Scaffold with Hierarchical Pore
           Architecture
    • Authors: Kathy Ye Morgan; Demetra Sklaviadis, Zachary L. Tochka, Kristin M. Fischer, Keith Hearon, Thomas D. Morgan, Robert Langer, Lisa E. Freed
      Abstract: Multi‐material polymer scaffolds with multiscale pore architectures are characterized and tested with vascular and heart cells as part of a platform for replacing damaged heart muscle. Vascular and muscle scaffolds are constructed from a new material, poly(limonene thioether) (PLT32i), which meets the design criteria of slow biodegradability, elastomeric mechanical properties, and facile processing. The vascular–parenchymal interface is a poly(glycerol sebacate) (PGS) porous membrane that meets different criteria of rapid biodegradability, high oxygen permeance, and high porosity. A hierarchical architecture of primary (macroscale) and secondary (microscale) pores is created by casting the PLT32i prepolymer onto sintered spheres of poly(methyl methacrylate) (PMMA) within precisely patterned molds followed by photocuring, de‐molding, and leaching out the PMMA. Prefabricated polymer templates are cellularized, assembled, and perfused in order to engineer spatially organized, contractile heart tissue. Structural and functional analyses show that the primary pores guide heart cell alignment and enable robust perfusion while the secondary pores increase heart cell retention and reduce polymer volume fraction. A biodegradable elastomeric polymer template with slowly and rapidly degrading components and a hierarchical architecture of primary (macroscale) and secondary (microscale) pores enables heart and vascular cells to form organized engineered cardiac tissue. The platform supports microvessel perfusion and contractile heart muscle formation in vitro and, if validated in vivo, may aid in the regenerative repair of vascularized tissues.
      PubDate: 2016-06-13T08:15:53.05358-05:0
      DOI: 10.1002/adfm.201601146
       
  • Dynamics of Strong Coupling between J‐Aggregates and Surface Plasmon
           Polaritons in Subwavelength Hole Arrays
    • Abstract: A prototypical hybrid system formed by strong coupled gold hole arrays and J‐aggregate molecules is investigated by using both steady‐state spectroscopic method and ultrafast pump‐probe approach. In particular, the plasmonic response of the device has been tuned by modifying its periodicity thus to achieve the strongest possible coupling regime. It is found that in the transient absorption spectra, under upper band excitation, the bleaching signal from uncoupled J‐aggregate molecules completely disappears. Instead, two distinctive period dependent bleaching bands are formed, clearly fingerprint of the hybrid exciton‐plasmon state. The dynamics of these bands is also directly analyzed. A remarkable long lifetime is found especially for the upper band, corresponding to the presence of a trap state in its transient absorption spectra under resonance excitation. Such unique feature should provide a new approach to control quantum‐mechanical states under coherent coupling. Strongly coupled gold hole arrays and J‐aggregate molecules form a hybrid system that can be tuned to the strongest possible coupling regime. Transient absorption spectra show two distinctive, period‐independent bleaching bands, as a clear indicator of the hybrid exciton–plasmon state. These states show a remarkably long lifetime, corresponding to the presence of a trap state.
      PubDate: 2016-06-10T14:12:59.328997-05:
      DOI: 10.1002/adfm.201601452
       
  • Rational and Facile Construction of 3D Annular Nanostructures with Tunable
           Layers by Exploiting the Diffraction and Interference of Light
    • Abstract: This paper reports a rational and facile approach to fabricating arrays of 3D annular nanostructures with tunable layers by utilizing the diffraction and interference of UV light. Based on discretized Fresnel bright spots and standing waves formed within a photoresist film, the structures with nanoscale features are realized using simple, conventional photolithography. The 3D annular nanostructures are produced in arrays of single‐, double‐, and triple‐layered ring structures with the height of single layer on a 100 nm scale. The structural formation process and features of the nanostructures are analyzed and explained through 3D modeling that integrates the effects of both UV exposure dose and chemical kinetics. The approach to generating 3D annular nanostructures with tunable layers and discrete heights can be adapted for various applications that require the 3D structures fabricated over a large area with high throughput. Arrays of 3D annular nanostructures with tunable layers are constructed by utilizing the diffraction and interference of light through simple, conventional photolithographic process. Based on comprehensive analysis of structural formation process and nanoscale features, 3D annular nanostructures are generated as arrays of single‐, double‐ and triple‐layered ring structures with a single layer height on a 100 nm scale.
      PubDate: 2016-06-09T13:33:58.18692-05:0
      DOI: 10.1002/adfm.201505614
       
  • Pyrite‐Based Bi‐Functional Layer for Long‐Term Stability
           and High‐Performance of Organo‐Lead Halide Perovskite Solar
           Cells
    • Abstract: Organo‐lead halide perovskite solar cells (PSCs) have received great attention because of their optimized optical and electrical properties for solar cell applications. Recently, a dramatic increase in the photovoltaic performance of PSCs with organic hole transport materials (HTMs) has been reported. However, as of now, future commercialization can be hampered because the stability of PSCs with organic HTM has not been guaranteed for long periods under conventional working conditions, including moist conditions. Furthermore, conventional organic HTMs are normally expensive because material synthesis and purification are complicated. It is herein reported, for the first time, octadecylamine‐capped pyrite nanoparticles (ODA‐FeS2 NPs) as a bi‐functional layer (charge extraction layer and moisture‐proof layer) for organo‐lead halide PSCs. FeS2 is a promising candidate for the HTM of PSCs because of its high conductivity and suitable energy levels for hole extraction. A bi‐functional layer based on ODA‐FeS2 NPs shows excellent hole transport ability and moisture‐proof performance. Through this approach, the best‐performing device with ODA‐FeS2 NPs‐based bi‐functional layer shows a power conversion efficiency of 12.6% and maintains stable photovoltaic performance in 50% relative humidity for 1000 h. As a result, this study has the potential to break through the barriers for the commercialization of PSCs. A bi‐functional layer based on hydrophobic ligand capped FeS2 nanoparticles is an outstanding inorganic hole transporting materials (HTMs) for perovskite solar cells (PSCs). PSCs with FeS2 bi‐functional layer show high photovoltaic performance and improved long‐term stability because HTMs based on FeS2 have excellent hole transport ability and moisture‐proof performance. Our approach will contribute to reliability improvement of PSCs.
      PubDate: 2016-06-09T13:33:41.228937-05:
      DOI: 10.1002/adfm.201601119
       
  • Void Engineering in Metal–Organic Frameworks via Synergistic Etching
           and Surface Functionalization
    • Authors: Ming Hu; Yi Ju, Kang Liang, Tomoya Suma, Jiwei Cui, Frank Caruso
      Abstract: The rational design and engineering of metal–organic framework (MOF) crystals with hollow features has been used for various applications. Here, a top‐down strategy is established to construct hollow MOFs via synergistic etching and surface functionalization by using phenolic acid. The macrosized cavities are created inside various types of MOFs without destroying the parent crystalline framework, as evidenced by electron microscopy and X‐ray diffraction. The modified MOFs are simultaneously coated by metal–phenolic films. This coating endows the MOFs with the additional functionality of responding to near infrared irradiation to produce heat for potential photothermal therapy applications. A top‐down strategy to construct various hollow metal–organic frameworks (MOFs) is reported via synergistic etching and surface functionalization by using phenolic acid. Simultaneous surface modification not only allows precise etching inside the MOFs, but also results in a metal–phenolic coating on the MOFs. The metal–phenolic coating endows the MOFs with near infrared laser responsiveness.
      PubDate: 2016-06-09T13:33:15.99486-05:0
      DOI: 10.1002/adfm.201601193
       
  • Hierarchical Nanohybrids of Gold Nanorods and PGMA‐Based Polycations
           for Multifunctional Theranostics
    • Abstract: Organic/inorganic nanohybrids hold great importance in fabricating multifunctional theranostics to integrate therapeutic functions with real‐time imaging. Although Au nanorods (NRs) have been employed for theranostics, complicated design of materials limits their practical applications. In this work, new multifunctional theranostic agents are designed and synthesized employing Au NRs with desirable near‐infrared absorbance as the cores. A facile “grafting‐onto” approach is put forward to prepare the series of hierarchical nanohybrids (Au‐PGEA and Au‐PGED) of Au NRs and poly(glycidyl methacrylate)‐based polycations. The resultant nanohybrids can be utilized as gene carriers with high gene transfection performances. The structural effect of polycations on gene transfection is investigated in detail, and Au‐PGEA with abundant hydroxyl groups on the surface exhibits superior performance. Au‐PGEA nanohybrids are further validated to possess remarkable capability of combined photothermal therapy (PTT) and gene therapy (GT) for complementary tumor treatment. Moreover, significantly enhanced computed tomography (CT)/photoacoustic (PA) signals are detected both in vitro and in vivo, verifying the potential of Au‐PGEA for dual‐modal imaging with precise and accurate information. Therefore, these multifunctional nanohybrids fabricated from a simple and straightforward strategy are promising for in vivo dual‐modal CT/PA imaging guided GT/PTT therapy with high antitumor efficacy. Novel hierarchical nanohybrids of Au nanorods and poly(glycidyl methacrylate)‐based polycations are proposed for in vivo dual‐modal computed tomography/photoacoustic imaging guided gene therapy/photothermal therapy with high antitumor efficacy.
      PubDate: 2016-06-09T13:24:13.244441-05:
      DOI: 10.1002/adfm.201601418
       
  • Graphene Nanopores for Protein Sequencing
    • Authors: James Wilson; Leila Sloman, Zhiren He, Aleksei Aksimentiev
      Abstract: An inexpensive, reliable method for protein sequencing is essential to unraveling the biological mechanisms governing cellular behavior and disease. Current protein sequencing methods suffer from limitations associated with the size of proteins that can be sequenced, the time, and the cost of the sequencing procedures. This study reports the results of all‐atom molecular dynamics simulations that investigated the feasibility of using graphene nanopores for protein sequencing. The study is focused on the biologically significant phenylalanine‐glycine repeat peptides (FG‐nups)—parts of the nuclear pore transport machinery. Surprisingly, FG‐nups are found to behave similarly to single stranded DNA: The peptides adhere to graphene and exhibit stepwise translocation when subject to a transmembrane bias or a hydrostatic pressure gradient. Reducing the peptide's charge density or increasing the peptide's hydrophobicity is found to decrease the translocation speed. Yet, unidirectional and stepwise translocation driven by a transmembrane bias is observed even when the ratio of charged to hydrophobic amino acids is as low as 1:8. The nanopore transport of the peptides is found to produce stepwise modulations of the nanopore ionic current correlated with the type of amino acids present in the nanopore, suggesting that protein sequencing by measuring ionic current blockades may be possible. Results of molecular dynamics simulations suggest that unfolded peptides can pass through a graphene nanopore in a stepwise manner when subject to a transmembrane bias or a hydrostatic pressure gradient. Such nanopore transport produces stepwise modulations of the nanopore ionic current correlated with the type of amino acids present in the nanopore.
      PubDate: 2016-06-09T13:24:02.294313-05:
      DOI: 10.1002/adfm.201601272
       
  • Pyridinic‐Nitrogen‐Dominated Graphene Aerogels with
           Fe–N–C Coordination for Highly Efficient Oxygen Reduction
           Reaction
    • Authors: Xiaoyang Cui; Shubin Yang, Xingxu Yan, Jiugou Leng, Shuang Shuang, Pulickel M. Ajayan, Zhengjun Zhang
      Abstract: Here, pyridinic nitrogen dominated graphene aerogels with/without iron incorporation (Fe‐NG and NG) are prepared via a facile and effective process including freeze‐drying of chemically reduced graphene oxide with/without iron precursor and thermal treatment in NH3. A high doping level of nitrogen has been achieved (up to 12.2 at% for NG and 11.3 at% for Fe‐NG) with striking enrichment of pyridinic nitrogen (up to 90.4% of the total nitrogen content for NG, and 82.4% for Fe‐NG). It is found that the Fe‐NG catalysts display a more positive onset potential, higher current density, and better four‐electron selectivity for ORR than their counterpart without iron incorporation. The most active Fe‐NG exhibits outstanding ORR catalytic activity, high durability, and methanol tolerance ability that are comparable to or even superior to those of the commercial Pt/C catalyst at the same catalyst loading in alkaline environment. The excellent ORR performance can be ascribed to the synergistic effect of pyridinic N and Fe‐N x sites (where iron probably coordinates with pyridinic N) that serve as active centers for ORR. Our Fe‐NG can be developed into cost‐effective and durable catalysts as viable replacements of the expensive Pt‐based catalysts in practical fuel cell applications. Pyridinic‐nitrogen‐dominated graphene aerogels with iron incorporation (Fe‐NG) display better ORR catalytic activity than their counterpart without iron incorporation. The most active Fe‐NG exhibits outstanding ORR catalytic activity, high durability, and methanol tolerance ability that are comparable to or even superior to those of the commercial Pt/C catalyst at the same catalyst loading in alkaline environment.
      PubDate: 2016-06-09T13:23:52.793579-05:
      DOI: 10.1002/adfm.201601492
       
  • Training Neural Stem Cells on Functional Collagen Scaffolds for Severe
           Spinal Cord Injury Repair
    • Authors: Xing Li; Sumei Liu, Yannan Zhao, Jiayin Li, Wenyong Ding, Sufang Han, Bing Chen, Zhifeng Xiao, Jianwu Dai
      Abstract: Neural stem cells (NSCs) transplantation is regarded as a promising therapeutic strategy to treat severe spinal cord injury (SCI) by compensating the neuronal loss. However, significant challenges including long‐term survival, directed neuronal differentiation, and functional integration of the transplanted NSCs and their progenies within the host spinal cord are yet to be solved. In this study, NSCs are trained on differently modified collagen scaffolds to increase their neuronal differentiation rate when cultured under the simulated SCI microenvironment. Then, a functional scaffold is screened out, on which the cultured NSCs show high neuronal differentiation rate and generate both sensory and motor mature neurons. Subsequently, that NSC seeded functional scaffold is transplanted into a rat severe SCI model. The results show that higher endogenous neurogenesis efficiency as well as in vivo survival and neuronal differentiation rate of the grafted NSCs are observed. Moreover, both sensory and motor neurons are found to be differentiated from the grafted NSCs in the lesion site and those newly generated neurons can functionally interact with each other and the host neurons. Taken together, the in vitro training systems for modulating the differentiation profiles of NSCs are instructive and exhibit strong potentials for SCI treatments. Neural stem cells (NSCs) trained on the functional collagen scaffolds achieve comparatively high neuronal differentiation rate and generate both sensory and motor mature neurons. After transplanting the NSCs seeded functional scaffold into a rat severe spinal cord injury model, higher survival and neuronal differentiation rate of the grafted NSCs are observed. Moreover, the grafted NSCs can generate sensory and motor neurons throughout the lesion site.
      PubDate: 2016-06-09T13:23:44.944494-05:
      DOI: 10.1002/adfm.201601521
       
  • Non‐Volatile Polymer Electroluminescence Programmable with
           Ferroelectric Field‐Induced Charge Injection Gate
    • Authors: Ju Han Lee; Beomjin Jeong, Sung Hwan Cho, Eui Hyuk Kim, Cheolmin Park
      Abstract: Electroluminescence (EL) of organic and polymeric fluorescent materials programmable in the luminance is extremely useful as a non‐volatile EL memory with the great potential in the variety of emerging information storage applications for imaging and motion sensors. In this work, a novel non‐volatile EL memory in which arbitrarily chosen EL states are programmed and erased repetitively with long EL retention is demonstrated. The memory is based on utilizing the built‐in electric field arising from the remnant polarization of a ferroelectric polymer which in turn controls the carrier injection of an EL device. A device with vertically stacked components of a transparent bottom electrode/a ferroelectric polymer/a hole injection layer/a light emitting layer/a top electrode successfully emits light upon alternating current (AC) operation. Interestingly, the device exhibits two distinctive non‐volatile EL intensities at constant reading AC voltage, depending upon the programmed direct current (DC) voltage on the ferroelectric layer. DC programmed and AC read EL memories are also realized with different EL colors of red, green and blue. Furthermore, more than four distinguishable EL states are precisely addressed upon the programmed voltage input each of which shows excellent EL retention and multiple cycle endurance of more than 105 s and 102 cycles, respectively. A novel direct current programmed alternating current read non‐volatile polymer electroluminescence (EL) memory is developed by utilizing programmable polarization, i.e., built‐in electric field of a ferroelectric polymer. Arbitrarily chosen EL states are programmed by the controlled remnant polarization of the ferroelectric layer with excellent EL retention and write/erase endurance properties of more than 105 s and 102 cycles, respectively.
      PubDate: 2016-06-09T13:22:49.935226-05:
      DOI: 10.1002/adfm.201601773
       
  • Water‐Soluble Conjugated Polymers for the Detection and Inhibition
           of Protein Aggregation
    • Authors: Ran Chai; Chengfen Xing, Junjie Qi, Yibing Fan, Hongbo Yuan, Ruimin Niu, Yong Zhan, Jialiang Xu
      Abstract: Protein aggregation is etiologically associated with a wide range of devastating neurodegenerative diseases such as Alzheimer's and prion diseases, and therefore the new strategies for the detection and inhibition of protein aggregation are urgently desired. Herein, the capability of a cationic water‐soluble poly(phenylene vinylene) derivative (PPV‐NMe3 +) to detect and inhibit the protein aggregation has been explored, using the hen egg white lysozyme (HEWL) as a model system whose aggregation is triggered by UV illumination. The PPV‐NMe3 + binds efficiently to the surface of the HEWL aggregates driven by the hydrophobic interactions, leading to the reduction of interchain contacts and therefore the enhancement of fluorescence intensity of the conjugated polymer. Importantly, the hydrophobic interactions between HEWL and PPV‐NMe3 + compete with the interaction that dominates the formation of the HEWL self‐assembly, and the electrostatic repulsion between the neighboring PPV‐NMe3 +‐coated aggregates reduces and inhibits the further aggregation of HEWL. In this way, the water‐soluble conjugated polymer PPV‐NMe3 + serves as both the detector and inhibitor for the protein aggregation triggered by UV illumination, which promises advanced potential applications in the diagnose and prevention of diseases caused by protein aggregation. A water‐soluble poly(phenylene vinylene) derivative (PPV‐NMe3 +) has been applied to detect and inhibit hen egg white lysozyme (HEWL) aggregation triggered by UV illumination. The competition of the hydrophobic interactions between HEWL and PPV‐NMe3 + with that dominates the formation of the HEWL self‐assembly as well as the electrostatic repulsion between neighboring PPV‐NMe3 +‐coated aggregates reduces and inhibits the further aggregation of HEWL.
      PubDate: 2016-06-09T13:22:45.932634-05:
      DOI: 10.1002/adfm.201601621
       
  • Phosphorus‐Doped Perovskite Oxide as Highly Efficient Water
           Oxidation Electrocatalyst in Alkaline Solution
    • Authors: Yinlong Zhu; Wei Zhou, Jaka Sunarso, Yijun Zhong, Zongping Shao
      Abstract: Developing cost‐effective and efficient electrocatalysts for oxygen evolution reaction (OER) is of paramount importance for the storage of renewable energies. Perovskite oxides serve as attractive candidates given their structural and compositional flexibility in addition to high intrinsic catalytic activity. In a departure from the conventional doping approach utilizing metal elements only, here it is shown that non‐metal element doping provides an another attractive avenue to optimize the structure stability and OER performance of perovskite oxides. This is exemplified by a novel tetragonal perovskite developed in this work, i.e., SrCo0.95P0.05O3– δ (SCP) which features higher electrical conductivity and larger amount of O2 2−/O− species relative to the non‐doped parent SrCoO3– δ (SC), and thus shows improved OER activity. Also, the performance of SCP compares favorably to that of well‐developed perovskite oxides reported. More importantly, an unusual activation process with enhanced activity during accelerated durability test (ADT) is observed for SCP, whereas SC delivers deactivation for the OER. Such an activation phenomenon for SCP may be primarily attributed to the in situ formation of active A‐site‐deficient structure on the surface and the increased electrochemical surface area during ADT. The concept presented here bolsters the prospect to develop a viable alternative to precious metal‐based catalysts. Phosphorus‐doped perovskite oxide SrCo0.95P0.05O3– δ (SCP) is demonstrated for the first time as a high‐efficient oxygen evolution reaction (OER) electrocatalyst in alkaline solution. The SCP exhibits enhanced OER activity and stability compared to parent SrCoO3– δ (SC). More importantly, an activation process is observed for SCP during accelerated durability test, which primarily originates from the in situ formed Sr‐deficient layer on its surface.
      PubDate: 2016-06-09T13:22:19.237019-05:
      DOI: 10.1002/adfm.201601902
       
  • Piezoelectric Gold: Strong Charge‐Load Response in a
           Metal‐Based Hybrid Nanomaterial
    • Abstract: Impregnating the pores of nanoporous gold with aqueous electrolyte yields a hybrid nanomaterial with two separate and interpenetrating charge transport paths, electronic conduction in the metal and ionic conduction in the electrolyte. As the two paths are capacitively connected, space‐charge layers along the internal interfaces are coupled to electric potential differences between the paths and can be controlled or detected thereby. The present experiments show that the space charge couples to mechanical deformation of the hybrid material, so that external loading generates an electric current. The electric signal originates from charge displacement along the entire internal interface; the signal is particularly robust since the interface area is large. The charge transfer in response to load constitutes a piezoelectric response, yet the mechanism is quite different to classic piezoelectricity. The analysis in this work predicts links between electromechanical coupling parameters for strain sensing and actuation, which are in excellent agreement with the experiment. Active strain sensing is reported for a hybrid material of nanoporous gold and electrolyte, which generates electric current when strained. The apparent piezoelectric behavior arises from a polarization of internal interfaces. The charge‐sensor constant of the hybrid material outperforms d33 of a high‐performance piezoceramic 4000 fold.
      PubDate: 2016-06-08T03:27:06.795262-05:
      DOI: 10.1002/adfm.201600938
       
  • Surface‐Shielding Nanostructures Derived from Self‐Assembled
           Block Copolymers Enable Reliable Plasma Doping for Few‐Layer
           Transition Metal Dichalcogenides
    • Abstract: Precise modulation of electrical and optical properties of 2D transition metal dichalcogenides (TMDs) is required for their application to high‐performance devices. Although conventional plasma‐based doping methods have provided excellent controllability and reproducibility for bulk or relatively thick TMDs, the application of plasma doping for ultrathin few‐layer TMDs has been hindered by serious degradation of their properties. Herein, a reliable and universal doping route is reported for few‐layer TMDs by employing surface‐shielding nanostructures during a plasma‐doping process. It is shown that the surface‐protection oxidized polydimethylsiloxane nanostructures obtained from the sub‐20 nm self‐assembly of Si‐containing block copolymers can preserve the integrity of 2D TMDs and maintain high mobility while affording extensive control over the doping level. For example, the self‐assembled nanostructures form periodically arranged plasma‐blocking and plasma‐accepting nanoscale regions for realizing modulated plasma doping on few‐layer MoS2, controlling the n‐doping level of few‐layer MoS2 from 1.9 × 1011 cm−2 to 8.1 × 1011 cm−2 via the local generation of extra sulfur vacancies without compromising the carrier mobility. Rigid surface‐shielding nanostructures are fabricated on few‐layer transition metal dichalcogenides transistors by self‐assembly of silicon‐containing block copolymers. With precisely controlled plasma‐accepting and plasma‐protecting regions, desulfurization at the plasma‐accepting regions leads to n‐doping effect without compromising the pristine carrier mobility. In addition, doping concentration and types are controlled by adjusting process parameters.
      PubDate: 2016-06-07T05:45:45.517335-05:
      DOI: 10.1002/adfm.201600654
       
  • Self‐Propelled Supercapacitors for On‐Demand Circuit
           Configuration Based on WS2 Nanoparticles Micromachines
    • Abstract: The miniaturization of energy storage microcapacitors to develop portable electronic devices has been of high recent interest. Here, microsupercapacitors microrobot is fabricated using membrane template‐assisted electrodeposition of WS2 nanoparticles (WS2NPs)/polyaniline (PANI) and platinum (Pt) layers. The microrobot navigates in the microchannel and attaches itself as part of the electrical circuit. The attached WS2NPs‐PANI/Pt microrobots enhance the capacitive behavior of the circuit significantly. The results presented in this work open the door for the development of smart and miniaturized functional micromotors that are able to self‐assemble to on‐demand circuits. Self‐propelled microsupercapacitors, which have dual function as catalytically propelled devices and high capacitance for on‐demand delivery of the capacitive elements in electronic systems, are presented. This is a conceptually new work showing that autonomous nano‐ and microdevices can be used for an on‐demand construction and adjustment of the electronic devices.
      PubDate: 2016-06-07T05:45:32.385291-05:
      DOI: 10.1002/adfm.201601165
       
  • Efficient Piezoelectric Energy Harvesters Utilizing (001) Textured Bimorph
           PZT Films on Flexible Metal Foils
    • Abstract: Extracting energy from low vibration frequencies (
      PubDate: 2016-06-07T05:45:24.241459-05:
      DOI: 10.1002/adfm.201601347
       
  • Ultrafast Assembly of PS‐PDMS Block Copolymers on 300 mm Wafers by
           Blending with Plasticizers
    • Abstract: Next‐generation lithography techniques based on the self‐assembly of block copolymers (BCPs) are promising methods for high‐resolution pattering. BCPs with a high incompatibility (high‐χ), such as polystyrene‐polydimethylsiloxane (PS‐PDMS), show encouraging results in terms of resolution. In the strong segregation regime, the high diffusive energy barrier of PS‐PDMS excessively reduces the self‐assembly kinetics; this is why solvent–vapor annealing is typically adopted to shorten the self‐assembly time. Plasticizers are generally used to reduce the glass transition temperature (Tg) of polymers. In this study, commercial plasticizers such as dioctylsebacate and diisooctyl adipate are blended with PS‐PDMS polymers, and their influence on the self‐assembly process is investigated. The intrinsic PS selectivity of the plasticizers brings the BCP to form PS‐PDMS micelles, which results in highly ordered self‐assembled body‐centered cubic spherical PS‐PDMS after spin‐coating without any annealing. The negligible vapor pressure of plasticizers and the decrease of Tg allow the high mobility of PS‐PDMS micelles in thin films. A transition into a stable horizontal cylindrical morphology is then possible by ultrafast thermal annealing (30 s). The complete process, from the BCP deposition to the final pattern transfer into Si, is presented on 300 mm standard wafers, which makes this method promising for microelectronic industrial integration. High‐χN PS‐PDMS block copolymers are blended with plasticizers in order to trigger self‐assembly. The plasticizers allow high mobility of PS‐PDMS micelles, which leads to homogeneous self‐assembled structures after deposition and a well‐aligned morphology transition by 30 s thermal annealing. The process has been tested on 300 mm wafers of standard graphoepitaxy trenches, and pattern transfer into Si substrates has been successfully performed.
      PubDate: 2016-06-07T05:45:18.773427-05:
      DOI: 10.1002/adfm.201601469
       
  • Molecular Origin of the Charge Carrier Mobility in Small Molecule Organic
           Semiconductors
    • Abstract: Small‐molecule organic semiconductors are used in a wide spectrum of applications, ranging from organic light emitting diodes to organic photovoltaics. However, the low carrier mobility severely limits their potential, e.g., for large area devices. A number of factors determine mobility, such as molecular packing, electronic structure, dipole moment, and polarizability. Presently, quantitative ab initio models to assess the influence of these molecule‐dependent properties are lacking. Here, a multiscale model is presented, which provides an accurate prediction of experimental data over ten orders of magnitude in mobility, and allows for the decomposition of the carrier mobility into molecule‐specific quantities. Molecule‐specific quantitative measures are provided how two single molecule properties, the dependence of the orbital energy on conformation, and the dipole‐induced polarization determine mobility for hole‐transport materials. The availability of first‐principles based models to compute key performance characteristics of organic semiconductors may enable in silico screening of numerous chemical compounds for the development of highly efficient optoelectronic devices. A first‐principles‐based multiscale model is presented, which accurately predicts charge carrier mobility of different materials varying over ten orders of magnitude. The model allows for the decomposition of the carrier mobility into molecule‐specific quantities. The availability of fast and parameter‐free screening tools to compute macroscopic materials properties may enable in silico screening of the chemical compound space for the development of highly efficient optoelectronic devices.
      PubDate: 2016-06-07T05:45:04.197797-05:
      DOI: 10.1002/adfm.201601807
       
  • A Hydrogen‐Bonded‐Supramolecular‐Polymer‐Based
           Nanoprobe for Ratiometric Oxygen Sensing in Living Cells
    • Abstract: The first example of a ratiometric optical oxygen nanoprobe based on a hydrogen‐bonded supramolecular polymer has been reported. The supramolecular polymer based nanoprobe (SPNP) is prepared from the co‐assembly of a bis‐ureidopyrimidinone (bis‐UPy)‐containing phosphorescent indicator (Por(Pd)‐bisUPy), fluorescent reference dye (BF2‐bisUPy), and skeleton unit (DPA‐bisUPy) through quadruple hydrogen bonds by a mini‐emulsion method. The water‐dispersible SPNP is highly sensitive to oxygen (Q = 95%), with full reversibility, excellent storage stability and photostability, and good cell‐penetrating ability, and exhibits low cytotoxicity toward living cells. The preparation of the SPNP is straightforward and its function is easily tuned by changing the monomeric structure. This work is expected to lead to the design of other SPNPs for other important analytes in biological systems. The first water‐dispersible supramolecular‐polymer‐based ratiometric oxygen nanoprobe (SPNP) is reported. The preparation of the SPNP is straightforward and its function is easily tuned by changing the monomeric structures. The SPNP is highly sensitive to oxygen, with full reversibility, excellent storage stability and photostability, and good cell‐penetrating ability, and exhibit low cytotoxicity toward living cells.
      PubDate: 2016-06-07T05:44:17.359293-05:
      DOI: 10.1002/adfm.201601831
       
  • Nonvolatile Charge Injection Memory Based on Black Phosphorous 2D
           Nanosheets for Charge Trapping and Active Channel Layers
    • Authors: Young Tack Lee; Junyeong Lee, Hyunsu Ju, Jung Ah Lim, Yeonjin Yi, Won Kook Choi, Do Kyung Hwang, Seongil Im
      Abstract: 2D van der Waals atomic crystal materials have great potential for use in future nanoscale electronic and optoelectronic applications owing to their unique properties such as a tunable energy band gap according to their thickness or number of layers. Recently, black phosphorous (BP) has attracted significant interest because it is a single‐component material like graphene and has high mobility, a direct band gap, and exhibits ambipolar transition behavior. This study reports on a charge injection memory field‐effect transistor on a glass substrate, where few‐layer BPs act as the active channel and charge trapping layers, and Al2O3 films grown by atomic layer deposition act as the tunneling and blocking layers. Because of the ambipolar properties of BP nanosheets, both electrons and holes are involved in the charge trapping process, resulting in bilateral threshold voltage shifts with a large memory window of 22 V. Finally, a memory circuit of a resistive‐load inverter is implemented that converts analog signals (current) to digital signals (voltage). Such a memory inverter also shows a clear memory window and distinct memory on/off switching characteristics. Charge injection memory devices based on a black phosphorous (BP) nanosheet transistor with top gate geometry on a glass substrate are demonstrated. Because of the ambipolar properties of BP nanosheets, both electrons and holes are involved in the charge trapping process, resulting in bilateral threshold voltage shifts with a large memory window of 22 V.
      PubDate: 2016-06-07T05:42:38.969625-05:
      DOI: 10.1002/adfm.201602113
       
  • A Universal Platform for Macromolecular Deliveryinto Cells Using Gold
           Nanoparticle Layers via the Photoporation Effect
    • Authors: Zhonglin Lyu; Feng Zhou, Qi Liu, Hui Xue, Qian Yu, Hong Chen
      Abstract: Although promising, it is challenging to develop a simple and universal method for the high‐efficiency delivery of biomacromolecules into diverse cells. Here, a universal delivery platform based on gold nanoparticle layer (GNPL) surfaces is proposed. Upon laser irradiation, GNPL surfaces show such good photothermal properties that absorption of the laser energy causes a rapid increase in surface temperature, leading to enhanced membrane permeability of the cultured cells and the diffusion of macromolecules into the cytosol from the surrounding medium. The high‐efficiency delivery of different macromolecules such as dextran and plasmid DNA into different cell types is achieved, including hard‐to‐transfect mouse embryonic fibroblasts (mEFs) and human umbilical vein endothelial cells (HUVECs), while cell viability is well maintained under optimized irradiation conditions. The platform vastly outperforms the leading commercial reagent, Lipofectamine 2000, especially in transfecting hard‐to‐transfect cell lines (plasmid transfection efficiency: ≈53% vs ≈19% for mEFs and ≈44% vs ≈8% for HUVECs). Importantly, as the gold nanoparticles (GNPs) constituting the GNPL are firmly immobilized together, the potential cytotoxicity caused by endocytosis of GNPs is effectively avoided. This platform is reliable, efficient, and cost‐effective with high‐throughput and broad applicability across different cell types, opening up an innovative avenue for high‐efficiency intracellular delivery. A universal platform using gold nanoparticle layer (GNPL) as the photoporation reagent for macromolecular delivery is proposed. It achieves the high‐efficiency delivery of different macromolecules into various cell types, including hard‐to‐transfect cells. Importantly, as the gold nanoparticles (GNPs) that constitute the GNPL are firmly immobilized together, the potential cytotoxicity caused by endocytosis of GNPs is effectively avoided.
      PubDate: 2016-06-07T05:41:18.553178-05:
      DOI: 10.1002/adfm.201602036
       
  • A Robust Design for Cellular Vehicles of Gold Nanorods for Multimodal
           Imaging
    • Authors: Fulvio Ratto; Sonia Centi, Cinzia Avigo, Claudia Borri, Francesca Tatini, Lucia Cavigli, Claudia Kusmic, Beatrice Lelli, Sarah Lai, Stefano Colagrande, Francesco Faita, Luca Menichetti, Roberto Pini
      Abstract: The pursuit of more selectivity in the delivery of plasmonic particles to tumors is critical before their penetration into clinical applications as the photoacoustic imaging and the photothermal ablation of cancer. As their direct infusion into the bloodstream remains problematic, due to a multitude of biological barriers, the development of alternative approaches is emerging as a new challenge. In this context, the recruitment of homologous tumor‐tropic cells that may serve as Trojan horses stands out as a fascinating possibility. Here, a novel model of gold nanorods is presented that feature a composite shell and undergo efficient and reproducible endocytic uptake from murine macrophages, which is fine‐tunable over a broad range of conditions. These cells preserve their viability and more than 90% of their innate chemotactic behavior in vitro, even with a cargo exceeding 200 000 particles per cell. In addition, we show that these vehicles are detectible by photoacoustic imaging down to concentrations in the order of 1% in whole blood and by clinical X‐ray computed tomography below 10%, which is within the typical fraction of a leukocytic infiltrate in a tumor microenvironment, and may even work as contrast agents for the photothermal ablation of cancer. Hybrid particles with plasmonic bands in the near infrared are engineered to undergo consistent uptake from tumor‐tropic cells, without affecting their viability and chemotaxis. These cells may be recruited as Trojan horses to target tumors across all biological barriers and to enable their multimodal detection by photoacoustic imaging and X‐ray computed tomography and their destruction by photothermal ablation.
      PubDate: 2016-06-06T12:05:47.956255-05:
      DOI: 10.1002/adfm.201600836
       
  • Dendritic Platinum–Copper Alloy Nanoparticles as Theranostic Agents
           for Multimodal Imaging and Combined Chemophotothermal Therapy
    • Authors: Zhengjie Zhou; Kewen Hu, Rui Ma, Yang Yan, Bing Ni, Yunjiao Zhang, Longping Wen, Qiang Zhang, Yiyun Cheng
      Abstract: Theranostic nanoparticles that possess multiple diagnostic modalities and allow spatiotemporally controlled therapies can significantly improve therapeutic outcomes and reduce adverse effects. Here, an intelligent and biocompatible theranostic formulation is developed based on dendritic platinum–copper alloy nanoparticles (DPCN) for cancer therapy. DPCN have excellent photothermal effect, and can load anticancer drugs such as doxorubicin in their porous structure and release the loaded drugs in response to near infrared light or moderate acidic stimulus. They also inherently have multimodal imaging modalities. Upon the guidance of photoacoustic imaging, DPCN‐mediated photothermal treatment efficiently inhibits tumor growth in vivo. Furthermore, doxorubicin‐loaded DPCN completely suppress the tumor growth even under a low treatment temperature, which avoids hypothermia‐induced damage to normal tissues. Our study develops an excellent theranostic nanoparticle with inherent multimodal imaging and therapeutic modalities for chemophotothermal cancer therapy. Dendritic platinum–copper alloy nanoparticles (DPCN) are developed as an excellent theranostic agent. DPCN inherently possess multimodal imaging modalities, photothermal effect, and drug loading capability. Upon the guidance of photoacoustic imaging, DPCN‐mediated chemophotothermal treatment efficiently inhibits the tumor growth in vivo.
      PubDate: 2016-06-06T12:05:40.570025-05:
      DOI: 10.1002/adfm.201601754
       
  • Ultrafine Alloy Nanoparticles Converted from 2D Intercalated Coordination
           Polymers for Catalytic Application
    • Authors: Ping Li; Wen Liu, John S. Dennis, Hua Chun Zeng
      Abstract: Supported multimetallic alloy nanoparticles (NPs) have shown great potential for applications owing to combined functions of constituent metals, and more remarkably, enhanced physicochemical properties and even novel synergistic effects that are not possessed by their parent metals. Nevertheless, synthesizing this kind of nanocomposites has been a long‐standing challenge using conventional wet chemistry. Here, this study reports an efficient, versatile strategy for the preparation of multimetallic alloy NPs supported by layered double hydroxides (LDH) and/or layered double oxides (LDO). In this approach, different metal precursors are intercalated stepwise into the gallery space of LDH. Along with the coordination reaction between the metal precursors, 2D cyanide bridged coordination polymers (CP) are formed in the confined space. Afterward, supported multimetallic alloy NPs can be obtained via either liquid‐phase reduction or thermal autoreduction. Due to the homogeneous mixing of metals in the 2D CP, ultrafine alloy NPs can be obtained with high particulate uniformity and compositional tailorability. A large series of supported binary alloy NPs (FePd, FePt, CoPd, CoPt, NiPd, NiPt, and PtPd) and ternary alloy NPs (FePdPt, FeNiPt, FeCoPt, and NiCoPt) are successfully synthesized with this approach. The resulting supported multimetallic alloy NPs present great potential in numerous applications. To demonstrate their workability, one class of LDH/NiPd nanocomposite is explored as a model heterogeneous catalyst with respect to the carbon–carbon cross‐coupling reactions (Suzuki–Miyaura, Heck, and Sonogashira cross‐coupling reactions). A novel and versatile approach to construct supported ultrafine alloy nanoparticles from 2D intercalated coordination polymers in layered double hydroxides (LDH) is developed via simultaneous intercalation and coordination process followed with subsequent reduction. To demonstrate their workability, one class of the resulting supported alloy nanoparticles (LDH/NiPd nanocomposite), is explored to catalyze cross‐coupling reactions.
      PubDate: 2016-06-02T15:02:04.001076-05:
      DOI: 10.1002/adfm.201601174
       
  • Bulk Inclusions of Pyridazine‐Based Molecular Rotors in
           Tris(o‐phenylenedioxy)cyclotriphosphazene (TPP)
    • Abstract: A new class of rod‐shaped strongly dipolar molecular rotors for insertion into channels of hexagonal tris(o‐phenylenedioxy)cyclotriphosphazene (TPP) has been examined. Seven different 3,6‐disubstituted pyridazines and one singly 3‐substituted system have been prepared and studied by solid‐state nuclear magnetic resonance (NMR), X‐ray powder diffraction, and dielectric spectroscopy. NMR and X‐ray diffraction both show that all but one of these molecular rotors form hexagonal bulk inclusion compounds with TPP. In‐plane lattice parameters for the hexagonal phases increase with the size of the end group, which also controls the energy barriers for rotation of the pyridazine dipole. The barriers range from ≈4 kcal mol−1 for small or flexible end groups to less than 0.7 kcal mol−1 for 3‐methylbicyclo[1.1.1]pent‐1‐yl end groups after annealing to 235 °C, and an interpretation of these differences is offered. Computer modeling of the relaxed TPP channels followed by density functional calculation of the environment for one of the rotors provides quantitative agreement with the observed barrier. The systems with the lowest rotational barriers show signs of collective behavior, discussed in terms of antiferroelectric intrachannel and ferroelectric interchannel dipole–dipole interactions. A Curie temperature of 22 K is deduced for 3,6‐diadamant‐1′‐ylpyridazine, but no ordered dielectric phases are found. Conclusions have been drawn for improved rotor design. Rod‐shaped dipolar molecular rotors based on pyridazine have been synthesized and inserted as guests into the channels of hexagonal tris(o‐phenylenedioxy)cyclotriphosphazene host, as verified by solid‐state nuclear magnetic resonance and powder X‐ray diffraction. Dielectric spectroscopy reveals low rotational barriers, which are well reproduced by computer simulation. Some of the rotors give signs of collective behavior at low temperature.
      PubDate: 2016-06-01T12:50:51.160872-05:
      DOI: 10.1002/adfm.201600437
       
  • Ultrathin Epitaxial Ferromagnetic γ‐Fe2O3 Layer as High
           Efficiency Spin Filtering Materials for Spintronics Device Based on
           Semiconductors
    • Abstract: In spintronics, identifying an effective technique for generating spin‐polarized current has fundamental importance. The spin‐filtering effect across a ferromagnetic insulating layer originates from unequal tunneling barrier heights for spin‐up and spin‐down electrons, which has shown great promise for use in different ferromagnetic materials. However, the low spin‐filtering efficiency in some materials can be ascribed partially to the difficulty in fabricating high‐quality thin film with high Curie temperature and/or partially to the improper model used to extract the spin‐filtering efficiency. In this work, a new technique is successfully developed to fabricate high quality, ferrimagnetic insulating γ‐Fe2O3 films as spin filter. To extract the spin‐filtering effect of γ‐Fe2O3 films more accurately, a new model is proposed based on Fowler–Nordheim tunneling and Zeeman effect to obtain the spin polarization of the tunneling currents. Spin polarization of the tunneled current can be as high as −94.3% at 2 K in γ‐Fe2O3 layer with 6.5 nm thick, and the spin polarization decays monotonically with temperature. Although the spin‐filter effect is not very high at room temperature, this work demonstrates that spinel ferrites are very promising materials for spin injection into semiconductors at low temperature, which is important for development of novel spintronics devices. A spin polarization of the tunneled current as high as −94.3% at 2 K is achieved in epitaxial and ultrathin γ‐Fe2O3 layer. This work emphasizes that ferrimagnetic insulator spinel ferrites with high Curie temperatures are very promising materials as candidates for spintronics, particularly for spin injection into semiconductors.
      PubDate: 2016-06-01T06:39:13.658391-05:
      DOI: 10.1002/adfm.201504999
       
  • “Nano‐Fishnet” Structure Making Silk Fibers Tougher
    • Abstract: Based on the combined technologies of atomic force microscopy, X‐ray diffraction/scattering, Fourier transform infrared spectra analysis, etc., it is demonstrated that the nano‐fishnet‐like networks, one of the most flexible but toughest structures, turn out to be the basic structure of silk filaments. The force patterns of pulling individual fibrils allow the identification of the pathways of unfolding protein segments in stacking β‐crystallites, which reveal the fishnet‐like topology. The calculation shows that the β‐crystallites in silk nanofibrils are the cross‐linking points of the nano‐fishnets, which may enhance the toughness of silk filaments up to 1000 times, compared with amyloid‐like and unlinked string structures. It follows that the strong β‐sheet–β‐sheet interaction, a high degree of ordering, and a high density of β‐crystallites in silk fibers toughen the fishnet structure, then strengthen silk filaments, in consistency with the experiments for both spider and silkworm silks. The knowledge on the fishnet structure of silk fibers sheds light on the design and synthesis of either protein or synthetic fibers of ultraperformance in a more generic way. The fishnet structure in silk fibrils determines the unusual mechanical performance of spider silk and silkworm silk fibers. Via the stacking of the secondary structure, the β‐crystallites give rise to the nano‐fishnets in silk fibrils, where stronger β‐sheet–β‐sheet interactions, the better alignment, and higher density of β‐crystallites enhance the mechanical performance of silk fibers.
      PubDate: 2016-06-01T06:38:40.872737-05:
      DOI: 10.1002/adfm.201600813
       
  • Asymmetrical Triboelectric Nanogenerator with Controllable Direct
           Electrostatic Discharge
    • Authors: Zongming Su; Mengdi Han, Xiaoliang Cheng, Haotian Chen, Xuexian Chen, Haixia Zhang
      Abstract: This paper presents a novel asymmetrical triboelectric nanogenerator (A‐TENG) to produce, detect, and analyze contact electrification and electrostatic discharge (ESD) in the atmosphere. Thanks to the asymmetrical structures, the direct and continuous ESD phenomenon without any external electronic circuits is, for the first time, discovered by our experiments in A‐TENG. Different from traditional contact‐mode TENG, asymmetrical contact pairs introduce an unstable state, which causes a continuous surface charge increase and eventually the air breakdown. The ESD phenomena have been simultaneously detected and confirmed by a low‐dark‐current photoelectric detector. Four different steps have been summarized to describe irregular ESD transition processes before their stable state. At the same time, the frequency and efficiency of ESD have been generally regulated and controlled by systematically investigating several key influence factors (contact materials, contact pressure, tilted angle, surface morphology, etc.). This asymmetrical structure has proved TENG as powerful and real‐time analytical equipment to explore fundamentals of contact electrification and ESD. Meanwhile, three necessary premises for ESD in TENG can be selectively avoided for the improvement of the stability of TENG. A novel asymmetrical triboelectric nanogenerator (A‐TENG) is presented to produce electrostatic discharge (ESD) in the atmosphere for the first time. The ESD phenomenon can be easily detected by abrupt output decline of TENG and photoelectric detector. This study can be helpful in stability improvement of TENG design.
      PubDate: 2016-06-01T06:34:49.31862-05:0
      DOI: 10.1002/adfm.201600909
       
  • Improved All‐Polymer Solar Cell Performance by Using Matched Polymer
           Acceptor
    • Authors: Shaohua Shi; Jianyu Yuan, Guanqun Ding, Michael Ford, Kunyuan Lu, Guozheng Shi, Jianxia Sun, Xufeng Ling, Yong Li, Wanli Ma
      Abstract: By the introduction of different building blocks and side‐chains, a series of donor–acceptor type polymer acceptors containing naphthalene diimide have been successfully prepared. The theoretical and experimental results show that the molecular design effectively tunes the energy levels, solubility, and coplanarity of the acceptor polymers. The intermolecular packing, which has been considered as a key factor in the bulk heterojunction morphology, has been adjusted by changing the coplanarity. As a result of improved morphology and fine‐tuned energy levels, a power conversion efficiency of 6.0% has been demonstrated for the optimized devices, which is among the highest‐efficiencies for reported all‐polymer solar cells. The improved device performance may be attributed to the resemble crystallinity of the donor/acceptor polymers, which can lead to the optimal phase separation morphology balancing both charge transfer and transport. By incorporating different building blocks and modifying side‐chains, a series of donor–acceptor polymers have been successfully synthesized. Optimized all‐polymer solar cells have been demonstrated a high power conversion efficiency of 6.0%. The improved device performance may be attributed to the resemble crystallinity of the donor/acceptor polymers, which can lead to the balanced charge transfer and transport.
      PubDate: 2016-06-01T06:34:42.186598-05:
      DOI: 10.1002/adfm.201601037
       
  • Thermally Reduced Graphene Oxide Nanohybrids of Chiral Functional
           Naphthalenediimides for Prostate Cancer Cells Bioimaging
    • Abstract: This study reports on the supramolecular assemblies formed between planar carbon systems (PCSs) such as thermally reduced graphene oxide (TRGO) and its small‐molecule model system coronene and a series of d‐ and l‐α amino acid derivatized naphthalenediimides (NDIs) where the halogen substituents (X = F, Cl, Br, I) are varied systematically. Confocal fluorescence microscopy of NDIs, NDI•coronene, and NDI•TRGO complexes is performed proving the uptake and stability of such complexes in the cellular environment and suggesting their potential as prostate cancer imaging agents. 1H NMR and UV–vis spectroscopy studies support the formation of charge transfer complexes whereby the increasing polarizability and general electronegativity of the aryl halide substituted at the NDI periphery influence the magnitude of the association constants in the ground state between NDI and coronene. Complexation between NDIs and PCSs also results in stable photoexcited assemblies within the solution (coronene) as well as the dispersed phased (TRGO). Fluorescence emission titrations and 2‐photon time correlated single photon counting measurements suggest the existence of dynamic quenching mechanisms upon the excitation of the fluorophore in the presence of the carbon substrates, as these methods are sensitive proves for the subtle changes in the NDI environment. The series of halogenated species used exerts supramolecular control over the degree of surface assembly on the TRGO and over the interactions with the coronene molecule, and this is of relevance to the assembly of future biosensing platforms as these materials can both be viewed as congeners of graphene. Finally, MTT assays carried out in PC‐3 cells demonstrate that the stable noncovalent functionalization of TRGO and coronene with either l or d NDIs remarkably improves the cellular viability in the presence of such graphene‐like materials. These phenomena are of particular relevance for the understanding of the direct donor–acceptor interactions in solutions which govern the design of nanomaterials with future biosensing and bioimaging applications. Halogenated amino acids within the naphthalenediimide (NDI) moieties can positively influence the degree of surface binding when designing functional nanomaterials. The noncovalent functionalization of planar carbon systems such as thermally reduced graphene oxide and coronene by using amino acid tagged NDIs is reported here and its potential as a prostate cancer bioimaging agent investigated via fluorescence microscopy, UV–vis, fluorescence spectroscopy, NMR, CD, TCSPC, SEM, TEM, and EDX.
      PubDate: 2016-06-01T06:34:35.512747-05:
      DOI: 10.1002/adfm.201601123
       
  • Fluidic Processing of High‐Performance ZIF‐8 Membranes on
           Polymeric Hollow Fibers: Mechanistic Insights and Microstructure Control
    • Authors: Kiwon Eum; Ali Rownaghi, Dalsu Choi, Ramesh R. Bhave, Christopher W. Jones, Sankar Nair
      Abstract: Recently, a methodology for fabricating polycrystalline metal‐organic framework (MOF) membranes has been introduced – referred to as interfacial microfluidic membrane processing – which allows parallelizable fabrication of MOF membranes inside polymeric hollow fibers of microscopic diameter. Such hollow fiber membranes, when bundled together into modules, are an attractive way to scale molecular sieving membranes. The understanding and engineering of fluidic processing techniques for MOF membrane fabrication are in their infancy. Here, a detailed mechanistic understanding of MOF (ZIF‐8) membrane growth under microfluidic conditions in polyamide‐imide hollow fibers is reported, without any intermediate steps (such as seeding or surface modification) or post‐synthesis treatments. A key finding is that interfacial membrane formation in the hollow fiber occurs via an initial formation of two distinct layers and the subsequent rearrangement into a single layer. This understanding is used to show how nonisothermal processing allows fabrication of thinner (5 μm) ZIF‐8 films for higher throughput, and furthermore how engineering the polymeric hollow fiber support microstructure allows control of defects in the ZIF‐8 membranes. The performance of these engineered ZIF‐8 membranes is then characterized, which have H2/C3H8 and C3H6/C3H8 mixture separation factors as high as 2018 and 65, respectively, and C3H6 permeances as high as 66 GPU. Formation of metal‐organic framework membranes in microscopic hollow fibers proceeds via specific mechanisms that combine interfacial reaction and crystallization with reactant transport under microfluidic conditions. It is shown that these mechanisms can be understood and then controlled by approaches such as nonisothermal processing and modification of fiber microstructure, leading to high‐performance ZIF‐8 membranes for olefin and hydrogen production.
      PubDate: 2016-06-01T06:33:47.598992-05:
      DOI: 10.1002/adfm.201601550
       
  • Stretchable Twisted‐Pair Transmission Lines for Microwave Frequency
           Wearable Electronics
    • Authors: Yei Hwan Jung; Juhwan Lee, Yijie Qiu, Namki Cho, Sang June Cho, Huilong Zhang, Subin Lee, Tong June Kim, Shaoqin Gong, Zhenqiang Ma
      Abstract: Stretchable electrical interconnects based on serpentines combined with elastic materials are utilized in various classes of wearable electronics. However, such interconnects are primarily for direct current or low‐frequency signals and incompatible with microwave electronics that enable wireless communication. In this paper, design and fabrication procedures are described for stretchable transmission line capable of delivering microwave signals. The stretchable transmission line has twisted‐pair design integrated into thin‐film serpentine microstructure to minimize electromagnetic interference, such that the line's performance is minimally affected by the environment in close proximity, allowing its use in thin‐film bioelectronics, such as the epidermal electronic system. Detailed analysis, simulations, and experimental results show that the stretchable transmission line has negligible changes in performance when stretched and is operable on skin through suppressed radiated emission achieved with the twisted‐pair geometry. Furthermore, stretchable microwave low‐pass filter and band‐stop filter are demonstrated using the twisted‐pair structure to show the feasibility of the transmission lines as stretchable passive components. These concepts form the basic elements used in the design of stretchable microwave components, circuits, and subsystems performing important radio frequency functionalities, which can apply to many types of stretchable bioelectronics for radio transmitters and receivers. The design of stretchable high‐frequency transmission lines with twisted‐pair geometry integrated into stretchable serpentines for wearable applications is presented. This transmission line that is in the form of ultrathin, conformal structure can transmit microwave frequency signals with low radio frequency and radiation losses, which is feasible as electrical interconnects for epidermal electronic systems requiring high‐speed wireless communication capabilities.
      PubDate: 2016-06-01T01:01:18.516683-05:
      DOI: 10.1002/adfm.201600856
       
  • Zinc Ferrite Photoanode Nanomorphologies with Favorable Kinetics for
           Water‐Splitting
    • Abstract: The n‐type semiconducting spinel zinc ferrite (ZnFe2O4) is used as a photoabsorber material for light‐driven water‐splitting. It is prepared for the first time by atomic layer deposition. Using the resulting well‐defined thin films as a model system, the performance of ZnFe2O4 in photoelectrochemical water oxidation is characterized. Compared to benchmark α‐Fe2O3 (hematite) films, ZnFe2O4 thin films achieve a lower photocurrent at the reversible potential. However, the oxidation onset potential of ZnFe2O4 is 200 mV more cathodic, allowing the water‐splitting reaction to proceed at a lower external bias and resulting in a maximum applied‐bias power efficiency (ABPE) similar to that of Fe2O3. The kinetics of the water oxidation reaction are examined by intensity‐modulated photocurrent spectroscopy. The data indicate a considerably higher charge transfer efficiency of ZnFe2O4 at potentials between 0.8 and 1.3 V versus the reversible hydrogen electrode, attributable to significantly slower surface charge recombination. Finally, nanostructured ZnFe2O4 photoanodes employing a macroporous antimony‐doped tin oxide current collector reach a five times higher photocurrent than the flat films. The maximum ABPE of these host–guest photoanodes is similarly increased. Zinc ferrite thin films prepared by atomic layer deposition exhibit slow surface electron/hole recombination during photoelectrochemical water oxidation. Nanostructuring can be used to significantly increase their photocurrent.
      PubDate: 2016-05-31T13:42:17.791911-05:
      DOI: 10.1002/adfm.201600461
       
  • Long Distance Enhancement of Nonlinear Optical Properties Using Low
           Concentration of Plasmonic Nanostructures in Dye Doped Monolithic
           Sol–Gel Materials
    • Abstract: Monolithic sol–gel silica composites incorporating platinum‐based chromophores and various types of gold nanoparticles (AuNPs) are prepared and polished to high optical quality. Their photophysical properties are investigated. The glass materials show well‐defined localized surface plasmon resonance (SPR) absorbance from the visible to NIR. No redshifts of the AuNP plasmon absorption peaks due to the increase in nanoparticle doping concentration are observed in the glasses, proving that no or very small SPR coupling effects occur between the AuNPs. At 600 nm excitation, but not at 532 nm, the AuNPs improve the nonlinear absorption performance of glasses codoped with 50 × 10−3 m of a Pt‐acetylide chromophore. The glasses doped with lower concentrations of AuNPs (2–5 μm average distance) and 50 × 10−3 m in chromophore, show a marked improvement in nonlinear absorption, with no or only small improvement for the more highly AuNP doped glasses. This study shows the importance of excitation wavelength and nanoparticle concentration for composite systems employing AuNPs to improve two‐photon absorption of chromophores. Monolithic sol–gel silica composites incorporating platinum‐based chromophores and various types of gold nanoparticles are obtained and their photophysical properties are fully investigated. They exhibit important enhancement of optical nonlinearities in particular at unexpected low concentration of gold nanoparticles. This unusual result demonstrates the possibility of long distance metal to molecule interaction in a hybrid matrix.
      PubDate: 2016-05-31T13:42:12.192548-05:
      DOI: 10.1002/adfm.201601646
       
  • Utilization of the Antiferromagnetic IrMn Electrode in Spin Thermoelectric
           Devices and Their Beneficial Hybrid for Thermopiles
    • Abstract: The thermoelectric effect in various magnetic systems, in which electric voltage is generated by a spin current, has attracted much interest owing to its potential applications in energy harvesting, but its power generation capability has to be improved further for actual applications. In this study, the first instance of the formation of a spin thermopile via a simplified and straightforward method which utilizes two distinct characteristics of antiferromagnetic IrMn is reported: the inverse spin Hall effect and the exchange bias. The former allows the IrMn efficiently to convert the thermally induced spin current into a measurable voltage, and the latter can be used to control the spin direction of adjacent ferromagnetic materials. It is observed that a thermoelectric signal is successfully amplified in spin thermopiles with exchange‐biased IrMn/CoFeB structures, where an alternating magnetic alignment is formed using the IrMn thickness dependence of the exchange bias. The scalable signal on a number of thermopiles allowing a large‐area application paves the way toward the development of practical spin thermoelectric devices. A detailed model analysis is also provided for a quantitative understanding of the thermoelectric voltages, which consist of the spin Seebeck and anomalous Nernst contributions. A simple and straightforward method of spin thermopiling using antiferromagnetic IrMn is demonstrated. The IrMn is a novel electrode in spin thermoelectrics not only for enhanced thermopower but also for modulation of magnetic configuration. The scalable signal amplification in spin thermopiles with exchange‐biased structures allowing a large‐area application paves the way toward the development of practical thermoelectric devices.
      PubDate: 2016-05-30T08:40:37.909427-05:
      DOI: 10.1002/adfm.201505514
       
  • Flexible Plasmonic Metasurfaces with User‐Designed Patterns for
           Molecular Sensing and Cryptography
    • Authors: Xiangjiang Liu; Jiajun Wang, Longhua Tang, Lijuan Xie, Yibin Ying
      Abstract: Flexible plasmonic metasurfaces have garnered considerable attention because the material's mechanical flexibility enables new functionalities and integrated applications. Here, by adopting low‐cost materials and simple techniques, we demonstrate a method of fabricating large flexible metasurfaces with arbitrary user‐designed iridescent patterns. These naked‐eye recognizable patterns together with their excellent plasmonic activities have yielded new functionalities and novel applications. Demonstrations include plasmonic sensing, reflective displays, developing new encryption strategies and integrated devices, etc. Moreover, the low fabrication cost (
      PubDate: 2016-05-30T08:40:34.593272-05:
      DOI: 10.1002/adfm.201601154
       
  • Reinventing Butyl Rubber for Stretchable Electronics
    • Authors: Akhil Vohra; Heather L. Filiatrault, Stanley D. Amyotte, R. Stephen Carmichael, Natalie D. Suhan, Conrad Siegers, Lorenzo Ferrari, Gregory J. E. Davidson, Tricia Breen Carmichael
      Abstract: The development of stretchable electronic devices that are soft and conformable has relied heavily on a single material—polydimethylsiloxane—as the elastomeric substrate. Although polydimethylsiloxane has a number of advantageous characteristics, its high gas permeability is detrimental to stretchable devices that use materials sensitive to oxygen and water vapor, such as organic semiconductors and oxidizable metals. Failing to protect these materials from atmosphere‐induced decomposition leads to premature device failure; therefore, it is imperative to develop elastomers with gas barrier properties that enable stretchable electronics with practical lifetimes. Here, butyl rubber—a material with an intrinsically low gas permeability traditionally used in the innerliners of tires to maintain air pressure—is reinvented for stretchable electronics. This new material is smooth and optically transparent, possesses the low gas permeability typical of butyl rubber, and vastly outperforms polydimethylsiloxane as an encapsulating barrier to prevent the atmospheric degradation of sensitive electronic materials and the premature failure of functioning organic devices. The merits of transparent butyl rubber presented here position this material as an important counterpart to polydimethylsiloxane that will enable future generation stretchable electronics. An elastomer long known for its excellent gas impermeability—butyl rubber—is reinvented for use in stretchable electronics to protect sensitive device materials and extend the lifetimes of stretchable devices. A new transparent butyl rubber formulation is reported, and its use as stretchable gas barrier for materials and devices sensitive to oxygen and moisture, such as organic semiconductors and light emitting devices, is demonstrated.
      PubDate: 2016-05-30T08:36:54.445594-05:
      DOI: 10.1002/adfm.201601283
       
  • Overall Water Splitting Catalyzed Efficiently by an Ultrathin
           Nanosheet‐Built, Hollow Ni3S2‐Based Electrocatalyst
    • Abstract: Making highly efficient catalysts for an overall ​water splitting reaction is vitally important to bring solar/electrical‐to‐hydrogen energy conversion processes into reality. Herein, the synthesis of ultrathin nanosheet‐based, hollow MoOx/Ni3S2 composite microsphere catalysts on nickel foam, using ammonium molybdate as a precursor and the triblock copolymer pluronic P123 as a structure‐directing agent is reported. It is also shown that the resulting materials can serve as bifunctional, non‐noble metal electrocatalysts with high activity and stability for the hydrogen evolution reaction (HER) as well as the oxygen evolution reaction (OER). Thanks to their unique structural features, the materials give an impressive water‐splitting current density of 10 mA cm−2 at ≈1.45 V with remarkable durability for >100 h when used as catalysts both at the cathode and the anode sides of an alkaline electrolyzer. This performance for an overall water splitting reaction is better than even those obtained with an electrolyzer consisting of noble metal‐based Pt/C and IrOx/C catalytic couple—the benchmark catalysts for HER and OER, respectively. A novel, non‐noble metal‐based water splitting electrocatalyst comprising nickel foam‐supported, ultrathin nanosheet‐built, hollow MoOx/Ni3S2 microspheres has been synthesized. This material gives an impressive water‐splitting current density of 10 mA cm−2 at ≈1.45 V with remarkable durability for >100 h when used as electrocatalysts both at the cathode and the anode sides of an alkaline electrolyzer.
      PubDate: 2016-05-30T08:36:50.946669-05:
      DOI: 10.1002/adfm.201601315
       
  • Bioinspired Nanocomposites: Ordered 2D Materials Within a 3D Lattice
    • Authors: Matteo Di Giosia; Iryna Polishchuk, Eva Weber, Simona Fermani, Luca Pasquini, Nicola M. Pugno, Francesco Zerbetto, Marco Montalti, Matteo Calvaresi, Giuseppe Falini, Boaz Pokroy
      Abstract: Composites, materials composed of two or more materials—metallic, organic, or inorganic—usually exhibit the combined physical properties of their component materials. The result is a material that is superior to conventional monolithic materials. Advanced composites are used in a variety of industrial applications and therefore attract much scientific interest. Here the formation of novel carbon‐based nanocomposites is described via incorporation of graphene oxide (GO) into the crystal lattice of single crystals of calcite. Incorporation of a 2D organic material into single‐crystal lattices has never before been reported. To characterize the resulting nanocomposites, high‐resolution synchrotron powder X‐ray diffraction, electron microscopy, transmission electron microscopy, fluorescence microscopy and nanoindentation tests are employed. A detailed analysis reveals a layered distribution of GO sheets incorporated within the calcite host. Moreover, the optical and mechanical properties of the calcite host are altered when a carbon‐based nanomaterial is introduced into its lattice. Compared to pure calcite, the composite GO/calcite crystals exhibits lower elastic modulus and higher hardness. The results of this study show that the incorporation of a 2D material within a 3D crystal lattice is not only feasible but also can lead to the formation of hybrid crystals exhibiting new properties. A novel single‐crystalline‐based composite is fabricated through the incorporation of graphene oxide into the crystal lattice of calcite. The material is characterized by state‐of‐the‐art tolls such as high‐resolution aberration‐corrected transmission electron microscopy, synchrotron diffraction, nanomechanical testing, and optical measurements. In contrast to pure calcite the composite hybrid exhibits fluorescence and enhancement in mechanical properties.
      PubDate: 2016-05-30T08:36:46.598654-05:
      DOI: 10.1002/adfm.201601318
       
  • Configuration‐Dependent Electrically Tunable Van der Waals
           Heterostructures Based on MoTe2/MoS2
    • Authors: Feng Wang; Lei Yin, Zhen Xing Wang, Kai Xu, Feng Mei Wang, Tofik Ahmed Shifa, Yun Huang, Chao Jiang, Jun He
      Abstract: Van der Waals heterostructures (vdWHs), obtained by artificially stacking 2D layered material (2DLM) plains upon each other, are brand new structures that have exhibited novel electronic and optoelectronic properties and attracted a great deal of attention. So far, the results are only based on devices with symmetrical configurations: devices predominated by vdWH parts, or cross‐like configurations combined with both vdWHs and extra individual 2DLM layers. Quite different gate tunable phenomena have been observed for these two configurations even though 2DLMs with similar band alignments were used, which may be due to the different device configurations utilized. For a deeper understanding, rational investigation on configuration‐dependent properties of vdWHs is needed. Here, using MoTe2/MoS2 as an example, vdWH device is artificially designed with two asymmetrical configurations. Through comparing the respective results, it is found that the properties that stem only from the vdWH, i.e., the rectification behavior and open voltage in photovoltaic effect, are independent of the device structures. However, other properties, i.e., drain currents, short circuit currents, and photoreponse performances, strongly depend on the configuration used. These results give a guideline on studying the intrinsic properties of vdWHs and optimizing the device structures for better performances. Using MoTe2/MoS2 as a typical example, the role of device configuration on the electronic and optoelectronic properties of van der Waals heterostructures is studied. It is found that the rectification behavior and open voltage are independent of the configuration. However, the drain currents, short circuit currents, and photoreponse performances strongly depend on the configuration used.
      PubDate: 2016-05-30T08:36:42.711365-05:
      DOI: 10.1002/adfm.201601349
       
  • Toward a Magnesium‐Iodine Battery
    • Authors: Federico Bertasi; Fatemeh Sepher, Gioele Pagot, Stephen J. Paddison, Vito Di Noto
      Abstract: The quest for new electrolyte and cathode materials is a crucial point for beyond‐lithium‐ion energy storage systems. Following this, an electrolyte for secondary magnesium batteries based on a new iodoaluminate ionic liquid and δ‐MgI2 is reported. Promising electrochemical performance in terms of Mg plating‐stripping, coulombic efficiency, and conductivity, demonstrates the potential of this iodine‐based system for future Mg secondary batteries. Electrolytes for secondary magnesium batteries based on a new iodoaluminate ionic liquid and δ‐MgI2 are reported. Promising electrochemical performance in terms of Mg plating‐stripping, coulombic efficiency, and conductivity, demonstrates the potential of this iodine‐based system for future Mg secondary batteries.
      PubDate: 2016-05-30T08:11:52.132785-05:
      DOI: 10.1002/adfm.201601448
       
  • Hierarchical Ni–Co Hydroxide Petals on Mechanically Robust Graphene
           Petal Foam for High‐Energy Asymmetric Supercapacitors
    • Authors: Guoping Xiong; Pingge He, Dini Wang, Qiangqiang Zhang, Tengfei Chen, Timothy S. Fisher
      Abstract: A hierarchical structure consisting of Ni–Co hydroxide nanopetals (NCHPs) grown on a thin free‐standing graphene petal foam (GPF) has been designed and fabricated by a two‐step process for pseudocapacitive electrode applications. The mechanical behavior of GPFs has been, for the first time to our knowledge, quantitatively measured from in situ scanning electron microscope characterization of the petal foams during in‐plane compression and bending processes. The Young's modulus of a typical GPF is 3.42 GPa, indicating its outstanding mechanical robustness as a nanotemplate. The GPF/NCHP electrodes exhibit volumetric capacitances as high as 765 F cm−3, equivalent to an areal capacitance of 15.3 F cm−2 and high rate capability. To assess practical functionality, two‐terminal asymmetric solid‐state supercapacitors with 3D GPF/NCHPs as positive electrodes are fabricated and shown to exhibit outstanding energy and power densities, with maximum average energy density of ≈10 mWh cm−3 and maximum power density of ≈3 W cm−3, high rate capability (a capacitance retention of ≈60% at 100 mA cm−2), and excellent long‐term cyclic stability (full capacitance retention over 15 000 cycles). A hierarchical structure of Ni–Co hydroxide nanopetals grown on thin free‐standing graphene petal foam has been fabricated by a two‐step process and characterized as a pseudocapacitive electrode. The electrode exhibits volumetric capacitances as high as 765 F cm−3, equivalent to an areal capacitance of 15.3 F cm−2 and high rate capability.
      PubDate: 2016-05-27T05:52:26.719202-05:
      DOI: 10.1002/adfm.201600879
       
  • Multi‐Length Scaled Silver Nanowire Grid for Application in
           Efficient Organic Solar Cells
    • Authors: Jiang Wu; Xinglu Que, Qin Hu, Deying Luo, Tanghao Liu, Feng Liu, Thomas P. Russell, Rui Zhu, Qihuang Gong
      Abstract: Transparent conducting electrodes (TCEs) with multi‐length scaled structure are promising candidates as a potential replacement for indium tin oxide (ITO). In this work, multi‐length scaled silver nanowire (AgNW) grids are demonstrated as TCEs for organic solar cells. The multi‐length scale silver nanowire grids are prepared by top‐down patterning using a neutral vapor etching process. Patterning AgNW film into multi‐length scale grid structures could improve the optical transmittance and enhance the use of incident photons. Based on these multi‐length scale AgNW grids, inverted bulk heterojunction polymer solar cells with power conversion efficiency up to 9.02% are fabricated, which are higher than that based on the original AgNW films and comparable to that based on ITO. Multi‐length scaled silver nanowire (AgNW) grids are prepared as transparent conducting electrodes through a neutral vapor etching process. Organic solar cells with power conversion efficiency up to 9.02% are fabricated based on the multi‐length scaled AgNW grids, which is higher than that based on original AgNW films and comparable to that based on indium tin oxide.
      PubDate: 2016-05-27T05:51:47.400093-05:
      DOI: 10.1002/adfm.201601049
       
  • Waveguiding Microactuators Based on a Photothermally Responsive
           Nanocomposite Hydrogel
    • Authors: Ying Zhou; Adam W. Hauser, Nakul P. Bende, Mark G. Kuzyk, Ryan C. Hayward
      Abstract: The incorporation of gold nanoparticles within thermally responsive poly(N‐isopropyl acrylamide) hydrogels provides a simple means to define photothermally addressable materials. Relying on such composite gels, it is established here that micropatterned bilayer photoactuators demonstrate rapid and highly reversible bending and unbending behavior in response to illumination with visible light. In addition to actuation by free space light, as in most previous research on such responsive nanocomposite hydrogels, light from a 532 nm laser is also waveguided through a plastic optical fiber directly into the photoactuator, providing remotely controllable actuators that do not require line‐of‐sight access. A micropatterned waveguiding photoactuator consisting of a bilayer with a photothermally responsive composite poly(N‐isopropyl acrylamide) hydrogel with Au nanoparticles is fabricated with photolithography and shows rapid and reversible light‐responsive actuation. The controlling light source is waveguided through an optical fiber connected to the photoactuator, enabling remote control without the need for maintaining line‐of‐sight access to the device.
      PubDate: 2016-05-27T02:13:01.658483-05:
      DOI: 10.1002/adfm.201601569
       
  • Monitoring the Formation of a CH3NH3PbI3–xClx Perovskite during
           Thermal Annealing Using X‐Ray Scattering
    • Authors: Alexander T. Barrows; Samuele Lilliu, Andrew J. Pearson, David Babonneau, Alan D. F. Dunbar, David G. Lidzey
      Abstract: Grazing incidence wide and small angle X‐ray scattering (GIWAXS and GISAXS) measurements have been used to study the crystallization kinetics of the organolead halide perovskite CH3NH3PbI3–xClx during thermal annealing. In situ GIWAXS measurements recorded during annealing are used to characterize and quantify the transition from a crystalline precursor to the perovskite structure. In situ GISAXS measurements indicate an evolution of crystallite sizes during annealing, with the number of crystallites having sizes between 30 and 400 nm increasing through the annealing process. Using ex situ scanning electron microscopy, this evolution in length scales is confirmed and a concurrent increase in film surface coverage is observed, a parameter crucial for efficient solar cell performance. A series of photovoltaic devices are then fabricated in which perovskite films have been annealed for different times, and variations in device performance are explained on the basis of X‐ray scattering measurements. Crystallization of the perovskite CH3NH3PbI3–xClx during thermal annealing of a precursor film is studied using in situ grazing incidence wide angle and small angle X‐ray scattering measurements. These results can explain the evolution of device performance with annealing time, and optimized films lead to solar cells with average power conversion efficiencies of over 12%.
      PubDate: 2016-05-26T01:01:03.928168-05:
      DOI: 10.1002/adfm.201601309
       
  • Selective Enhancement of Inner Tube Photoluminescence in Filled
           Double‐Walled Carbon Nanotubes
    • Authors: Philip Rohringer; Lei Shi, Paola Ayala, Thomas Pichler
      Abstract: A highly selective enhancement of the optical response of the inner tubes of double‐walled carbon nanotubes has been identified upon transformation of the residual C atoms inside the hollow core to linear carbon chains (LCC). By varying the growth conditions and using standardized suspensions, it has been observed that this optical response depends sensitively on the tube diameter and LCC growth yield. It is reported how the formation of LCC by postsynthesis annealing at 1400 °C leads to an increase of the photoluminescence (PL) signal of the inner tubes up to a factor of 6 for tubes with (8,3) chirality. This behavior can be attributed to a local charge transfer from the inner tubes to the carbon chains, counterbalancing quenching mechanisms induced by the outer tubes. These findings provide a viable pathway to enhance the low PL quantum yield of double‐walled carbon nanotubes and proof the capability of inner tubes to exhibit photoluminescence. An enhancement of the inner tube's photoluminescence from double‐walled carbon nanotubes is achieved by the incorporation of linear carbon chains into the hollow core of the inner tubes. This effect can be tailored by varying the length of the chains. For appropriate inner tubes with suitable diameters, an amplification of the photoluminescence intensity is found up to a factor of 6 upon filling.
      PubDate: 2016-05-25T15:46:51.867048-05:
      DOI: 10.1002/adfm.201505502
       
  • Resistive Switching Memory Integrated with Nanogenerator for
           Self‐Powered Bioimplantable Devices
    • Abstract: Resistive random access memory (ReRAM) devices powered by piezoelectric nanogenerators (NGs) have been investigated for their application to future implantable biomedical devices. Biocompatible (Na0.5K0.5)NbO3 (NKN) films that are grown at 300 °C on TiN/SiO2/Si and flexible TiN/Polyimide (TiN‐PI) substrates are used for ReRAM and NGs, respectively. These NKN films have an amorphous phase containing NKN nanocrystals with a size of 5.0 nm. NKN ReRAM devices exhibit typical bipolar switching behavior that can be explained by the formation and rupture of oxygen‐vacancy filaments. They have good ReRAM properties such as a large ratio of RHRS to RLRS as well as high reliability. The NKN film grown on flexible TiN‐PI substrate exhibits a high piezoelectric strain constant of 50 pm V−1. The NKN NG has a large open‐circuit output voltage of 2.0 V and a short‐circuit output current of 40 nA, which are sufficient to drive NKN ReRAM devices. Stable switching properties with a large ON/OFF ratio of 102 are obtained from NKN ReRAM driven by NKN NG. For self‐powered bioimplantable device applications, a resistive random access memory (ReRAM) driven by a piezoelectric nanogenerator (NG) is developed. Biocompatible (Na0.5K0.5)NbO3 (NKN) lead‐free piezoelectric thin films are used for both ReRAM and NG. The NKN ReRAM powered by NKN NG shows a stable memory performance, which can be applied to bioMEMS.
      PubDate: 2016-05-25T15:46:48.352524-05:
      DOI: 10.1002/adfm.201505569
       
  • Smart Threads: Double‐Twisted Conductive Smart Threads Comprising a
           Homogeneously and a Gradient‐Coated Thread for Multidimensional
           Flexible Pressure‐Sensing Devices (Adv. Funct. Mater. 23/2016)
    • Authors: Yanlong Tai; Gilles Lubineau
      Pages: 4037 - 4037
      Abstract: On page 4078 Y. Tai and G. Lubineau describe double‐twisted smart threads (DTSTs) that they assemble into a flexible pressure sensor. One thread is coated with a homogeneous thickness of SWCNTs to detect the intensity of an applied load and the other is coated with a graded thickness of SWCNTs to identify the position of the load along the thread. These DTSTs will present a promising application to portable and wearable devices like E‐skins.
      PubDate: 2016-06-20T09:38:00.785316-05:
      DOI: 10.1002/adfm.201670142
       
  • Asymmetric Supercapacitors: Preparation of MnCo2O4@Ni(OH)2
           Core–Shell Flowers for Asymmetric Supercapacitor Materials with
           Ultrahigh Specific Capacitance (Adv. Funct. Mater. 23/2016)
    • Authors: Yan Zhao; Linfeng Hu, Shuyan Zhao, Limin Wu
      Pages: 4038 - 4038
      Abstract: A novel supercapacitor electrode composed of multicomponent MnCo2O4@Ni(OH)2 belt‐based core‐shell nanoflowers is reported by L. M. Wu and co‐workers on page 4085. This hybrid electrode exhibits ultrahigh specific capacitance and its asymmetric supercapacitor device also displays excellent electrochemical performance in terms of energy density, power density and cycling lifespan, which excel most of the previous reported nickel, cobalt, manganese oxides/hydroxides.
      PubDate: 2016-06-20T09:38:01.835676-05:
      DOI: 10.1002/adfm.201670143
       
  • Contents: (Adv. Funct. Mater. 23/2016)
    • Pages: 4039 - 4045
      PubDate: 2016-06-20T09:37:58.356686-05:
      DOI: 10.1002/adfm.201670144
       
  • Reality Check for Nanomaterial‐Mediated Therapy with 3D Biomimetic
           Culture Systems
    • Pages: 4046 - 4065
      Abstract: The recent progresses in tissue engineering and nanomaterial‐based therapeutics/theranostics have led to the ever increasing utilization of 3D in vitro experimental models as the bona fide culture systems to evaluate the therapeutic/theranostic effects of nanomedicine. Compared to the use of conventional 2D culture platforms, 3D biomimetic cultures offer unmatched advantages as relevant physiological and pathological elements can be incorporated to allow better characterization of the engineered bio‐nanomaterials in the targeted tissue‐specific microenvironment. In this Feature Article, the current state‐of‐the‐art 3D in vitro models that have been developed for the evaluation of biosafety and efficacy of nano‐ therapeutics/theranostics targeting the colon, blood–brain barrier (BBB), lungs, skin tumor models to bridge the nanomedicine bench to pre‐clinical ravine are reviewed. Furthermore, the critical physicochemical parameters of the bio‐nanomaterials that govern its transport and biodistribution in a complex 3D microenvironment will be highlighted. The major challenges and future prospects of evaluating nanomedicine in the third dimension will also be discussed. In vitro 3D cell culture systems have emerged as important tools to evaluate the efficacy and toxicity of nano‐scale drug delivery vehicles. The use of 3D colon, blood brain barriers, lungs, skin, and tumor in vitro surrogates is here reviewed, to reveal salient insights that underpin the rational design of advanced nanomedicine.
      PubDate: 2016-04-18T02:26:35.593313-05:
      DOI: 10.1002/adfm.201600476
       
  • Bifunctional Catalysts: Bifunctional Nickel Phosphide Nanocatalysts
           Supported on Carbon Fiber Paper for Highly Efficient and Stable Overall
           Water Splitting (Adv. Funct. Mater. 23/2016)
    • Authors: Xiaoguang Wang; Wei Li, Dehua Xiong, Dmitri Y. Petrovykh, Lifeng Liu
      Pages: 4066 - 4066
      Abstract: L. F. Liu and co‐workers report on page 4067 the fabrication of a monolithic electrode comprising nickel phosphide nanosheet arrays supported on carbon fiber paper. The electrode shows excellent electrocatalytic performance toward both the hydrogen and oxygen evolution reactions. An alkaline electrolyzer assembled using two symmetrical electrodes exhibits high energy efficiency and exceptional stability for overall water splitting.
      PubDate: 2016-06-20T09:37:59.10201-05:0
      DOI: 10.1002/adfm.201670146
       
  • Bifunctional Nickel Phosphide Nanocatalysts Supported on Carbon Fiber
           Paper for Highly Efficient and Stable Overall Water Splitting
    • Authors: Xiaoguang Wang; Wei Li, Dehua Xiong, Dmitri Y. Petrovykh, Lifeng Liu
      Pages: 4067 - 4077
      Abstract: Self‐supported electrodes comprising carbon fiber paper (CP) integrated with bifunctional nickel phosphide (Ni‐P) electrocatalysts are fabricated by electrodeposition of Ni on functionalized CP, followed by a convenient one‐step phosphorization treatment in phosphorus vapor at 500 °C. The as‐fabricated CP@Ni‐P electrode exhibits excellent electrocatalytic performance toward hydrogen evolution in both acidic and alkaline solutions, with only small overpotentials of 162 and 250 mV, respectively, attaining a cathodic current density of 100 mA cm−2. Furthermore, the CP@Ni‐P electrode also exhibits superior catalytic performance toward oxygen evolution reaction (OER). An exceptionally high OER current of 50.4 mA cm−2 is achieved at an overpotential of 0.3 V in 1.0 m KOH. The electrode can sustain 10 mA cm−2 for 180 h with only negligible degradation, showing outstanding durability. Detailed microstructural and compositional studies reveal that upon OER in alkaline solution the surface Ni‐P is transformed to NiO covered with a thin Ni(OH)x layer, forming a Ni‐P/NiO/Ni(OH)x heterojunction, which presumably enhances the electrocatalytic performance for OER. Given the well‐defined bifunctionality, a full alkaline electrolyzer is constructed using two identical CP@Ni‐P electrodes as cathode and anode, respectively, which can realize overall water splitting with efficiency as high as 91.0% at 10 mA cm−2 for 100 h. Overall water splitting is realized at a high efficiency (91.0% at 10 mA cm−2) with excellent stability and durability by an alkaline electrolyzer made from self‐supported carbon fiber paper electrodes integrated with bifunctional nickel phosphide catalysts. The self‐supported electrode exhibits superior electrocatalytic performance toward both hydrogen evolution and oxygen evolution reactions in alkaline medium.
      PubDate: 2016-04-13T02:56:10.758215-05:
      DOI: 10.1002/adfm.201505509
       
  • Double‐Twisted Conductive Smart Threads Comprising a Homogeneously
           and a Gradient‐Coated Thread for Multidimensional Flexible
           Pressure‐Sensing Devices
    • Authors: Yanlong Tai; Gilles Lubineau
      Pages: 4078 - 4084
      Abstract: Fiber‐based, flexible pressure‐sensing systems have attracted attention recently due to their promising application as electronic skins. Here, a new kind of flexible pressure‐sensing device based on a polydimethylsiloxane membrane instrumented with double‐twisted smart threads (DTSTs) is reported. DTSTs are made of two conductive threads obtained by coating cotton threads with carbon nanotubes. One thread is coated with a homogeneous thickness of single‐walled carbon nanotubes (SWCNTs) to detect the intensity of an applied load and the other is coated with a graded thickness of SWCNTs to identify the position of the load along the thread. The mechanism and capacity of DTSTs to accurately sense an applied load are systematically analyzed. Results demonstrate that the fabricated 1D, 2D, and 3D sensing devices can be used to predict both the intensity and the position of an applied load. The sensors feature high sensitivity (between ≈0.1% and 1.56% kPa) and tunable resolution, good cycling resilience (>104 cycles), and a short response time (minimum 2.5 Hz). The presented strategy is a viable alternative for the design of simple, low‐cost pressure sensors. Conductive double‐twisted smart threads: one thread is coated with a homogeneous thickness of single‐walled carbon nanotubes (SWCNTs) to detect the intensity of an applied load and the other is coated with a graded thickness of SWCNTs to identify the position of the load along the thread. The basic performance of each thread is also presented.
      PubDate: 2016-03-17T12:53:06.413228-05:
      DOI: 10.1002/adfm.201600078
       
  • Preparation of MnCo2O4@Ni(OH)2 Core–Shell Flowers for Asymmetric
           Supercapacitor Materials with Ultrahigh Specific Capacitance
    • Authors: Yan Zhao; Linfeng Hu, Shuyan Zhao, Limin Wu
      Pages: 4085 - 4093
      Abstract: Supercapacitors have attracted much interest in the past decades owing to their important applications, but most of them are focused on solitary or simple metal oxides. Here, a novel supercapacitor electrode composed of multicomponent MnCo2O4@Ni(OH)2 belt‐based core–shell nanoflowers is reported by a facile and cost‐effective method. This hybrid electrode exhibits a significantly enhanced specific capacitance. An asymmetric supercapacitor based on this unique hybrid nanoflowers as anode and an activated carbon film as cathode demonstrates high energy density, high power density, and long cycling lifespan. Manganese cobalt spinel and nickel hydroxide hybrid belt‐based core–shell nanoflowers are successfully fabricated by a facile and cost‐effective strategy. The hybrid electrode exhibits an ultrahigh specific capacitance (2154 F g−1 at 5 A g−1). An asymmetric supercapacitor device based on this hybrid nanoflowers demonstrates high energy density, high power density, and long cycling lifespan.
      PubDate: 2016-04-23T03:40:39.795036-05:
      DOI: 10.1002/adfm.201600494
       
  • Bipolar Electrochemical Synthesis of WS2 Nanoparticles and Their
           Application in Magneto‐Immunosandwich Assay
    • Pages: 4094 - 4098
      Abstract: WS2 nanoparticles are prepared using bipolar electrochemistry. Obtained material exhibits high activity for hydrogen evolution reaction (HER) and it is used as a label in standard magneto‐immunosandwich assay for protein detection through HER. This new system shows high analytical performance in terms of a wide range, selectivity, sensitivity, and reproducibility. WS2 nanoparticles are prepared using bipolar electrochemistry. The potential applications of these materials as a label for protein detection are demonstrated utilizing hydrogen evolution reaction with electrochemical impedance spectroscopy as a transduction method. This new system shows high analytical performance in terms of a wide range, selectivity, sensitivity, and reproducibility.
      PubDate: 2016-04-23T03:40:30.279383-05:
      DOI: 10.1002/adfm.201600961
       
  • Mussel‐Inspired Approach to Constructing Robust Multilayered
           Alginate Films for Antibacterial Applications
    • Pages: 4099 - 4105
      Abstract: The exceptional mechanical properties of the byssus—the fibrous holdfast of mussels that provides underwater adhesion—have potential applications in medicine and technology. The catechol–Fe3+–catechol interaction underlies the unique properties of mussel byssus and has emerged as a tool for developing functional hybrid materials such as pH‐responsive, self‐healing gels. Herein, the construction of functional alginate (Alg) film on a solid substrate inspired by mussel byssus is reported. The approach consists of spin‐coating‐assisted deposition of Alg catechols onto a solid substrate and their subsequent crosslinking via catechol–Fe3+–catechol interactions. This yields robust and multilayered Alg films that are resistant to protein adsorption and suppress bacterial adhesion. This method can be used to create antibacterial films for coating implanted medical devices. A novel method for generating a multilayered alginate film is developed by mimicking the formation of cuticle layers around the byssus of mussels. The approach consists of spin‐coating‐assisted deposition of alginate catechols onto a solid substrate and their subsequent crosslinking via catechol–Fe3+–catechol interactions, which yields a robust alginate film that inhibits bacterial adhesion.
      PubDate: 2016-04-23T03:40:26.579876-05:
      DOI: 10.1002/adfm.201600613
       
  • The Excellence of Both Worlds: Developing Effective Double Perovskite
           Oxide Catalyst of Oxygen Reduction Reaction for Room and Elevated
           Temperature Applications
    • Pages: 4106 - 4112
      Abstract: The efficiencies of a number of electrochemical devices (e.g., fuel cells and metal‐air batteries) are mainly governed by the kinetics of the oxygen reduction reaction (ORR). Among all the good ORR catalysts, the partially substituted double perovskite oxide (AA′B2O5+δ) has the unique layered structure, providing a great flexibility regarding the optimization of its electronic structures and physicochemical properties. Here, it is demonstrated that the double perovskite oxide, i.e., NdBa0.75Ca0.25Co1.5Fe0.5O5+δ, is a good ORR catalyst at both room and elevated temperatures. Under ambient condition, its half‐wave potential of ORR in alkaline media is as low as 0.74 V versus RHE; at 650 °C, the cathodic polarization resistance is merely 0.0276 Ω cm2 according to a symmetric cell measurement, whereas the solid oxide fuel cells using this cathode exhibit a maximum power density of 1982 mW cm−2. From various materials characterizations, it is hypothesized that its excellent ORR activity is strongly correlated with the crystallographic, electronic, and defect structures of the materials. The double perovskite oxide, i.e., NdBa0.75Ca0.25Co1.5Fe0.5O5+δ, is demonstrated to be a good oxygen reduction reaction (ORR) catalyst at both room and elevated temperatures, and we also hypothesize that the excellent ORR activity strongly correlates to the crystallographic, electronic, and the defect structures of the material.
      PubDate: 2016-04-13T02:55:51.522898-05:
      DOI: 10.1002/adfm.201600339
       
  • Design of Multistimuli Responsive Hydrogels Using Integrated Modeling and
           Genetically Engineered Silk–Elastin‐Like Proteins
    • Authors: Wenwen Huang; Anna Tarakanova, Nina Dinjaski, Qin Wang, Xiaoxia Xia, Ying Chen, Joyce Y. Wong, Markus J. Buehler, David L. Kaplan
      Pages: 4113 - 4123
      Abstract: Elastomeric, robust, and biocompatible hydrogels are rare, while the need for these types of biomaterials in biomedical‐related uses remains high. Here, a new family of genetically engineered silk–elastin‐like proteins (SELPs) with encoded enzymatic crosslinking sites is developed for a new generation of stimuli‐responsive yet robust hydrogels. Input into the designs is guided by simulation and realized via genetic engineering strategies. The avoidance of gamma irradiation or chemical crosslinking during gel fabrication, in lieu of an enzymatic process, expands the versatility of these new gels for the incorporation of labile proteins and cells. In the present study, the new SELP hydrogels offer sequence‐dependent, reversible stimuli‐responsive features. Their stiffness covers almost the full range of the elasticity of soft tissues. Further, physical modification of the silk domains provides a secondary control point to fine‐tune mechanical stiffness while preserving stimuli‐responsive features, with implications for a variety of biomedical material and device needs. A new family of robust, tunable stimuli‐responsive hydrogels using rationally designed genetically engineered silk–elastin copolymers is reported. These dynamic hydrogels exhibit significant reversible changes in size, optical transparency, mechanical properties, and micromorphology upon exposure to designed target stimuli, dependent on the silk‐to‐elastin ratio or the guest amino acid residue designed in the elastin domain.
      PubDate: 2016-04-15T02:00:31.161418-05:
      DOI: 10.1002/adfm.201600236
       
  • Theranostic Oxygen Reactive Polymers for Treatment of Traumatic Brain
           Injury
    • Authors: Julia Xu; Menko Ypma, Peter A. Chiarelli, Joshua Park, Richard G. Ellenbogen, Patrick S. Stayton, Pierre D. Mourad, Donghoon Lee, Anthony J. Convertine, Forrest M. Kievit
      Pages: 4124 - 4133
      Abstract: Traumatic brain injury (TBI) is the leading cause of disability and death in children and adults under 45, with approximately ten million new cases per year worldwide. Significant progress has been made in understanding the complex pathophysiological response to TBI; however, reducing the damage associated with the reactive oxygen species (ROS)‐dependent secondary phase of the injury remains a substantial challenge. The development of an image‐guided, Gd‐conjugated, oxygen reactive polymer (ORP) to reduce ROS levels in damaged brain tissue is reported. ORP effectively sequesters ROS while remaining biocompatible even at elevated concentrations. ORP is retained in damaged brains of controlled cortical impact (CCI) mouse models of TBI for over 24 h when injected intravenously immediately and up to 3 h post‐CCI. The polymer reduces neurodegeneration tenfold and gliosis twofold in these mouse models. ORP shows initial promise as an effective therapy for TBI and helps provide a better understanding of nanomaterial interaction with damaged brain. Oxygen reactive polymers (ORP) can accumulate in damaged brain in mouse models of traumatic brain injury (TBI) and be visualized using magnetic resonance imaging. Accumulation and retention of ORP is accompanied by reduced neurodegeneration and gliosis, indicators of TBI severity. ORP should help further the understanding of nanomaterial interaction with TBI and hopefully leads to improved outcome for brain injury patients.
      PubDate: 2016-05-02T07:45:38.048653-05:
      DOI: 10.1002/adfm.201504416
       
  • Benchtop Fluorination of Fluorescent Nanodiamonds on a Preparative Scale:
           Toward Unusually Hydrophilic Bright Particles
    • Pages: 4134 - 4142
      Abstract: Fluorination of diamonds modulates their optical and electromagnetic properties and creates surfaces with increased hydrophobicity. In addition, fluorination of diamonds and nanodiamonds has been recently shown to stabilize fluorescent nitrogen‐vacancy centers, which can serve as extremely sensitive single atomic defects in a vast range of sensing applications from quantum physics to high‐resolution biological imaging. Traditionally, fluorination of carbon nanomaterials has been achieved using harsh and complex experimental conditions, creating hydrophobic interfaces with difficult dispersibility in aqueous environments. Here, a mild benchtop approach to nanodiamond fluorination is described using selective Ag+‐catalyzed radical substitution of surface carboxyls for fluorine. In contrast to other approaches, this high‐yielding procedure does not etch diamond carbons and produces a highly hydrophilic interface with mixed C−F and C−OH termination. This dual functionalization of nanodiamonds suppresses detrimental hydrophobic interactions that would lead to colloidal destabilization of nanodiamonds. It is also demonstrated that even a relatively low surface density of fluorine contributes to stabilization of negatively charged nitrogen‐vacancy centers and boosts their fluorescence. The simultaneous control of the surface hydrophilicity and the fluorescence of nitrogen‐vacancy centers is an important issue enabling direct application of fluorescent nanodiamonds as nanosensors for quantum optical and magnetometry measurements operated in biological environment. Hydrophilic fluorinated nanodiamonds with stabilized fluorescence from nitrogen‐vacancy centres are presented. A high‐yielding decarboxylative fluorination performed in acqueous environment creates a unique mixed C–F/C–OH surface. In contrast to other fluorine‐based diamond terminations, it retains the colloidal stability of nanodiamonds and boosts the fluorescence of NV− centers at the same time. This nonetching one‐step approach can be easily performed on the benchtop without special safety precautions.
      PubDate: 2016-05-02T07:57:08.833954-05:
      DOI: 10.1002/adfm.201504857
       
  • Layered Orthorhombic Nb2O5@Nb4C3Tx and TiO2@Ti3C2Tx Hierarchical
           Composites for High Performance Li‐ion Batteries
    • Pages: 4143 - 4151
      Abstract: Engineering electrode nanostructures is critical in developing high‐capacity, fast rate‐response, and safe Li‐ion batteries. This study demonstrates the synthesis of orthorhombic Nb2O5@Nb4C3Tx (or @Nb2CTx) hierarchical composites via a one‐step oxidation —in flowing CO2 at 850 °C —of 2D Nb4C3Tx (or Nb2CTx) MXene. The composites possess a layered architecture with orthorhombic Nb2O5 nanoparticles decorated uniformly on the surface of the MXene flakes and interconnected by disordered carbon. The composites have a capacity of 208 mAh g−1 at a rate of 50 mA g−1 (0.25 C) in 1–3 V versus Li+/Li, and retain 94% of the specific capacity with 100% Coulombic efficiency after 400 cycles. The good electrochemical performances could be attributed to three synergistic effects: (1) the high conductivity of the interior, unoxidized Nb4C3Tx layers, (2) the fast rate response and high capacity of the external Nb2O5 nanoparticles, and (3) the electron “bridge” effects of the disordered carbon. This oxidation method was successfully extended to Ti3C2Tx and Nb2CTx MXenes to prepare corresponding composites with similar hierarchical structures. Since this is an early report on producing this structure, there is much room to push the boundaries further and achieve better electrochemical performance. The oxidation of Nb4C3Tx MXene in CO2 results in a hierarchical T‐Nb2O5@Nb4C3Tx layered composite, that combines the high capacity of the external orthorhombic T‐Nb2O5, coupled with the high electrical conductivity of the interior unoxidized Nb4C3Tx and the electron bridge effect of the disordered carbon. This composite exhibits high capacity at high rate when used as Li‐ion battery anode.
      PubDate: 2016-05-09T08:10:20.64264-05:0
      DOI: 10.1002/adfm.201600682
       
  • Reusable and Long‐Lasting Active Microcleaners for Heterogeneous
           Water Remediation
    • Pages: 4152 - 4161
      Abstract: Self‐powered micromachines are promising tools for future environmental remediation technology. Waste‐water treatment and water reuse is an essential part of environmental sustainability. Herein, we present reusable Fe/Pt multi‐functional active microcleaners that are capable of degrading organic pollutants (malachite green and 4‐nitrophenol) by generated hydroxyl radicals via a Fenton‐like reaction. Various different properties of microcleaners, such as the effect of their size, short‐term storage, long‐term storage, reusability, continuous swimming capability, surface composition, and mechanical properties, are studied. It is found that these microcleaners can continuously swim for more than 24 hours and can be stored more than 5 weeks during multiple cleaning cycles. The produced microcleaners can also be reused, which reduces the cost of the process. During the reuse cycles the outer iron surface of the Fe/Pt microcleaners generates the in‐situ, heterogeneous Fenton catalyst and releases a low concentration of iron into the treated water, while the mechanical properties also appear to be improved due to both its surface composition and structural changes. The microcleaners are characterized by scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), nanoindentation, and finite‐element modeling (FEM). Reusable Fe/Pt multi‐functional active microcleaners are capable of degrading organic pollutants (malachite green and 4‐nitrophenol) by generated hydroxyl radicals via an in situ heterogeneous Fenton‐like reaction. The microcleaners can continuously swim for more than 24 hours and can be stored for more than 5 weeks and subjected to multiple cleaning cycles for reuse, which reduces the cost of the process.
      PubDate: 2016-04-14T06:16:03.399346-05:
      DOI: 10.1002/adfm.201600381
       
  • Highly Conductive Optical Quality Solution‐Processed Films of 2D
           Titanium Carbide
    • Authors: Andrew D. Dillon; Michael J. Ghidiu, Alex L. Krick, Justin Griggs, Steven J. May, Yury Gogotsi, Michel W. Barsoum, Aaron T. Fafarman
      Pages: 4162 - 4168
      Abstract: MXenes comprise a new class of solution‐dispersable, 2D nanomaterials formed from transition metal carbides and nitrides such as Ti3C2. Here, it is shown that 2D Ti3C2 can be assembled from aqueous solutions into optical quality, nanometer thin films that, at 6500 S cm−1, surpass the conductivity of other solution‐processed 2D materials, while simultaneously transmitting >97% of visible light per‐nanometer thickness. It is shown that this high conductivity is due to a metal‐like free‐electron density as well as a high degree of coplanar alignment of individual nanosheets achieved through spincasting. Consequently, the spincast films exhibit conductivity over a macroscopic scale that is comparable to the intrinsic conductivity of the constituent 2D sheets. Additionally, optical characterization over the ultraviolet‐to‐near‐infrared range reveals the onset of free‐electron plasma oscillations above 1130 nm. Ti3C2 is therefore a potential building block for plasmonic applications at near‐infrared wavelengths and constitutes the first example of a new class of solution‐processed, carbide‐based 2D optoelectronic materials. An aqueous colloidal Ti3C2‐based MXene is assembled by spincasting into highly aligned, optical‐quality films with a conductivity of 6500 S cm−1. The electrical and optical properties of this material are measured revealing that it is plasmonic in the near‐infrared. Comparison of the in‐plane DC conductivity and the optical conductivity indicates that the macroscopic material is nearly as conductive as the constituent nanosheets.
      PubDate: 2016-04-09T14:57:53.986259-05:
      DOI: 10.1002/adfm.201600357
       
  • Dual‐Targeted Photopenetrative Delivery of Multiple
           Micelles/Hydrophobic Drugs by a Nanopea for Enhanced Tumor Therapy
    • Pages: 4169 - 4179
      Abstract: A photoresponsive pea‐like capsule (nanopea) that also represents a photothermal agent is constructed by wrapping multiple polymer micelles (polyvinyl alcohol, PVA) in reduced graphene oxide nanoshells through a double emulsion approach. Resulting nanopeas can transport multiple PVA micelles containing the fully concealed hydrophobic drug docetaxel (DTX) which can be later released by a near‐infrared photoactuation trigger. Through integrating the rod‐shaped adhesion and lactoferrin (Lf) targeting, the nanopea enhances both uptake by cancer cellc in vitro and particle accumulation at tumor in vivo. A photopenetrative delivery of micelles/DTX to the tumor site is actuated by NIR irradiation which ruptures the nanopeas as well as releases nanosized micelles/DTX. This trigger also results in thermal damage to the tumor and increases the micelles/DTX permeability, facilitating drug penetration into the deep tumor far from blood vessels for thermal chemotherapy. This nanopea with the capability of imaging, enhanced tumor accumulation, NIR‐triggered tumor penetration, and hyperthermia ablation for photothermal chemotherapy boosts tumor treatment and shows potential for use in other biological applications. A reduced graphene oxide‐based capsule (nanopea) can carry multiple micelles containing hydrophobic therapeutic agents to achieve on‐demand drug delivery into deep tumor in vivo. Near‐IR irradiation triggers a burst‐like release of multiple ultrasmall micelles containing hydrophobic drugs which accomplish deep tumor penetration due to their small size and due to hyperthermia, all contributing to cell killing.
      PubDate: 2016-03-30T06:11:27.361326-05:
      DOI: 10.1002/adfm.201600498
       
  • Bendable Solar Cells from Stable, Flexible, and Transparent Conducting
           Electrodes Fabricated Using a Nitrogen‐Doped Ultrathin Copper Film
    • Pages: 4180 - 4191
      Abstract: Copper has attracted significant interests as an abundant and low‐cost alternative material for flexible transparent conducting electrodes (FTCEs). However, Cu‐based FTCEs still present unsolved technical issues, such as their inferior light transmittance and oxidation durability compared to conventional indium tin oxide (ITO) and silver metal electrodes. This study reports a novel technique for fabricating highly efficient FTCEs composed of a copper ultrathin film sandwiched between zinc oxides, with enhanced transparency and antioxidation performances. A completely continuous and smooth copper ultrathin film is fabricated by a simple room‐temperature reactive sputtering process involving controlled nitrogen doping (
      PubDate: 2016-04-13T02:52:39.073946-05:
      DOI: 10.1002/adfm.201600392
       
  • Enhanced Nanodrug Delivery to Solid Tumors Based on a Tumor
           Vasculature‐Targeted Strategy
    • Authors: Chenghua Song; Yejun Zhang, Chunyan Li, Guangcun Chen, Xiaofeng Kang, Qiangbin Wang
      Pages: 4192 - 4200
      Abstract: Tumor angiogenesis is a hallmark of tumor growth and metastasis, and inhibition of tumor angiogenesis is an effective strategy for tumor therapy. The high expression levels of specific biomarkers such as integrin receptors (e.g., αvβ3) in the endothelium of tumor vessels make angiogenesis an ideal target for drug delivery and thus tumor therapy. Herein, a new nanodrug (T&D@RGD‐Ag2S) is presented, which can effectively inhibit tumor growth by integrating the specific recognition peptide cyclo(Arg‐Gly‐Asp‐d‐Phe‐Cys) (cRGD) for tumor vascular targeting, the broad‐spectrum endothelial inhibitor O‐(chloroacetyl‐carbamoyl) fumagillol (TNP‐470), and chemotherapeutic drug doxorubicin (DOX) for synergetic tumor therapy. The results show that the T&D@RGD‐Ag2S nanodrug rapidly and specifically binds to the tumor vasculature after intravenous injection. Tumor vascular density is greatly reduced following effective angiogenesis inhibition by TNP‐470. Meanwhile, increased delivery of DOX deep into the tumor induces extensive tumor apoptosis, resulting in remarkable tumor growth inhibition in a human U87‐MG malignant glioma xenograft model. In addition, the therapeutic effects of T&D@RGD‐Ag2S on inhibiting tumor growth and decreasing vessel density are monitored in situ using near‐infrared II (NIR‐II) fluorescence imaging of Ag2S quantum dots. This tumor vasculature‐targeted strategy can be extended as a general method for treating a broad range of tumors and holds promise for future clinical applications. A novel nanodrug (T&D@RGD‐Ag2S) for tumor vasculature‐targeted therapy is presented, which can effectively inhibit tumor growth by integrating the specific tumor vascular targeting peptide cyclo(Arg‐Gly‐Asp‐d‐Phe‐Cys) (cRGD), the broad‐spectrum endothelial inhibitor O‐(chloroacetyl‐carbamoyl) fumagillol (TNP‐470) and chemotherapeutic drug doxorubicin for synergetic tumor therapy, as well as an in situ fluorescence imaging agent of Ag2S quantum dots.
      PubDate: 2016-04-13T05:42:56.17902-05:0
      DOI: 10.1002/adfm.201600417
       
  • Treatment of Malignant Brain Tumor by Tumor‐Triggered Programmed
           Wormlike Micelles with Precise Targeting and Deep Penetration
    • Authors: Lijuan Zeng; Lili Zou, Haijun Yu, Xinyu He, Haiqiang Cao, Zhiwen Zhang, Qi Yin, Pengcheng Zhang, Wangwen Gu, Lingli Chen, Yaping Li
      Pages: 4201 - 4212
      Abstract: The efficient and specific drug delivery to brain tumor is a crucial challenge for successful systemic chemotherapy. To overcome these limitations, here a tumor‐triggered programmed wormlike micelle is reported with precise targeting and deep penetration to treat malignant gliomas, which is composed of pH‐responsive mPEG‐b‐PDPA copolymer and bioreducible cyclic RGD peptide targeted cytotoxic emtansine (DM1) conjugates (RGD‐DM1). The RGD‐DM1 loaded nanoscaled wormlike micelles (RNW) exhibit nanometer‐sized wormlike assemblies with the transverse diameter of 21.3±1.8 nm and length within 60–600 nm, and the RGD targeting peptide in RNW is 4.2% in weight. RNW can be dissociated at intracellular acidic environments to release RGD‐DM1, and be further degraded into DM1 by cleavage of disulfide bonds in the reductive milieu. In particular, by exploiting the unique wormlike structure and the RGD targeting peptide modification, RNW can be endowed with obviously enhanced drug delivery to brain, precise targeting to brain tumor, deep penetration into tumor mass, and efficient internalization into glioma cells in a programmed manner, thereby surprisingly leading to an 88.9% inhibition on tumor progression in an orthotopic brain tumor model. Therefore, the properly designed RNW can provide a promising delivery platform for systemic chemotherapy of brain tumor. The efficient and specific delivery of drugs to brain tumors is a crucial challenge for successful systemic chemotherapy. By exploiting the unique wormlike structure and RGD targeting peptide modification, a tumor‐triggered programmed nanoscaled wormlike system (RNW) has been properly designed with precise targeting and deep penetration capability to treat malignant gliomas, providing a promising delivery platform for systemic chemotherapy of brain tumor.
      PubDate: 2016-04-13T02:52:33.326462-05:
      DOI: 10.1002/adfm.201600642
       
  • Inhibition of Ion Migration for Reliable Operation of Organolead Halide
           
    • Pages: 4213 - 4222
      Abstract: Organolead halide perovskites (OHPs) have attracted extensive attention as light harvesting materials for solar cells recently, because of their high charge carrier mobility, high photoconversion efficiencies, low cost, and simple methodology. Despite these advantages, the OHPs exhibit sweep‐dependent hysteresis behavior in current–voltage characteristics films, deteriorating the reliability of devices based on the OHPs. This study demonstrates reliable high on/off ratio (Ion/Ioff = 104) CH3NH3PbI3 broadband photodetectors with buffer layer‐free simple metal/semiconductor/metal lateral structure. At high external bias, poor on/off ratios and spikes in dark current and photocurrent are observed due to the migration of charged defect ions. The ion migration can be effectively inhibited at low external bias, and thus the devices show high Ion/Ioff ratios and spike‐free dark current and photocurrent. In addition, prevention of the prepoling in the CH3NH3PbI3 films by operating at the low external bias results in pronouncedly enhanced signal‐to‐noise ratios even under low intensity incident light. These results strongly propose that inhibiting the migration of charged defect ions in CH3NH3PbI3 films is a key in developing reliable high performance CH3NH3PbI3‐based devices. A reliable and high performance perovskite‐based lateral‐structure photodetector is achieved by inhibition of charged defect ions migration at low external bias. The electrical history severely affects the device performance and the poling at high external bias should be avoided in order to obtain reliable performances from CH3NH3PbI3 photodetectors, especially for detecting low‐intensity light.
      PubDate: 2016-03-21T03:26:25.371782-05:
      DOI: 10.1002/adfm.201600405
       
  • Carrier Type Control of WSe2 Field‐Effect Transistors by Thickness
           Modulation and MoO3 Layer Doping
    • Authors: Changjian Zhou; Yuda Zhao, Salahuddin Raju, Yi Wang, Ziyuan Lin, Mansun Chan, Yang Chai
      Pages: 4223 - 4230
      Abstract: Control of the carrier type in 2D materials is critical for realizing complementary logic computation. Carrier type control in WSe2 field‐effect transistors (FETs) is presented via thickness engineering and solid‐state oxide doping, which are compatible with state‐of‐the‐art integrated circuit (IC) processing. It is found that the carrier type of WSe2 FETs evolves with its thickness, namely, p‐type (15 nm). This layer‐dependent carrier type can be understood as a result of drastic change of the band edge of WSe2 as a function of the thickness and their band offsets to the metal contacts. The strong carrier type tuning by solid‐state oxide doping is also demonstrated, in which ambipolar characteristics of WSe2 FETs are converted into pure p‐type, and the field‐effect hole mobility is enhanced by two orders of magnitude. The studies not only provide IC‐compatible processing method to control the carrier type in 2D semiconductor, but also enable to build functional devices, such as, a tunable diode formed with an asymmetrical‐thick WSe2 flake for fast photodetectors. In the thickness‐dependent transport behavior of WSe2 transistors, it is revealed that all p‐type, ambipolar, and n‐type characteristics are obtained by merely varying the thickness of WSe2 flakes. The layer‐dependent band structure is a determining factor in achieving this strong thickness‐dependent transport behavior in WSe2 field‐effect transistors. The unique band structure of WSe2 also enables efficient p‐type doping in WSe2 by solid‐state oxide.
      PubDate: 2016-04-13T05:44:59.585868-05:
      DOI: 10.1002/adfm.201600292
       
  • WS2 Nanoparticles: Bipolar Electrochemical Synthesis of WS2 Nanoparticles
           and Their Application in Magneto‐Immunosandwich Assay (Adv. Funct.
           Mater. 23/2016)
    • Pages: 4231 - 4231
      Abstract: M. Pumera and co‐workers synthesized layered WS2 nanoparticles by bipolar electrochemistry by applying potential bias across two electrodes as described on page 4094. The obtained nanoparticles are successfully used as a label in a standard magneto‐immuno sandwich assay for protein detection through the hydrogen evolution reaction. The method offers a low cost approach to WS2 as sensor material in numerous biomedical applications.
      PubDate: 2016-06-20T09:38:01.345348-05:
      DOI: 10.1002/adfm.201670147
       
  • Antibacterial Films: Mussel‐Inspired Approach to Constructing Robust
           Multilayered Alginate Films for Antibacterial Applications (Adv. Funct.
           Mater. 23/2016)
    • Pages: 4232 - 4232
      Abstract: A novel method for generating a multilayered alginate film by mimicking the special properties of mussels was developed by J. S. Choi, W. K. Cho, S. M. Kang, and co‐workers, as described on page 4099. Generated multilayered alginate films are robust against chemical treatments and show excellent resistance to bacterial adhesion as well as protein adsorption. The method is promising to generate coatings of implants. Cover design by Kyoungche Kim.
      PubDate: 2016-06-20T09:37:56.486127-05:
      DOI: 10.1002/adfm.201670148
       
 
 
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