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CHEMISTRY (597 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 6)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 25)
ACS Catalysis     Full-text available via subscription   (Followers: 30)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 17)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 22)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 36)
ACS Nano     Full-text available via subscription   (Followers: 206)
ACS Photonics     Full-text available via subscription   (Followers: 9)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 20)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription  
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 7)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 4)
Advanced Functional Materials     Hybrid Journal   (Followers: 45)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 53)
Advances in Chemical Science     Open Access   (Followers: 12)
Advances in Chemistry     Open Access   (Followers: 11)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 16)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 17)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 10)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 2)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
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: 65)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 24)
American Journal of Plant Physiology     Open Access   (Followers: 12)
American Mineralogist     Full-text available via subscription   (Followers: 12)
Analyst     Full-text available via subscription   (Followers: 44)
Angewandte Chemie     Hybrid Journal   (Followers: 144)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 201)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 3)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 7)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 6)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 23)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 3)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 6)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 9)
Biochemistry     Full-text available via subscription   (Followers: 262)
Biochemistry Insights     Open Access   (Followers: 5)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 3)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 18)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 108)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 99)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 17)
Biosensors     Open Access   (Followers: 1)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 3)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 2)
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 9)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 65)
Catalysis for Sustainable Energy     Open Access   (Followers: 5)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 7)
Cellulose     Hybrid Journal   (Followers: 5)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 7)
Chemical and Engineering News     Free   (Followers: 12)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 68)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 21)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 18)
Chemical Reviews     Full-text available via subscription   (Followers: 164)
Chemical Science     Open Access   (Followers: 20)
Chemical Technology     Open Access   (Followers: 15)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemical Week     Full-text available via subscription   (Followers: 7)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 55)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
ChemInform     Hybrid Journal   (Followers: 7)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 4)
Chemistry - A European Journal     Hybrid Journal   (Followers: 127)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 16)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 8)
Chemistry International     Hybrid Journal   (Followers: 1)
Chemistry Letters     Full-text available via subscription   (Followers: 42)
Chemistry of Materials     Full-text available via subscription   (Followers: 175)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 8)
ChemPlusChem     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography Research International     Open Access   (Followers: 7)
Clay Minerals     Full-text available via subscription   (Followers: 8)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 10)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 3)
Combustion Science and Technology     Hybrid Journal   (Followers: 18)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Composite Interfaces     Hybrid Journal   (Followers: 5)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 1)
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 3)
CrystEngComm     Full-text available via subscription   (Followers: 10)
Current Catalysis     Hybrid Journal   (Followers: 1)
Current Metabolomics     Hybrid Journal   (Followers: 3)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 8)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 15)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 48)
Dalton Transactions     Full-text available via subscription   (Followers: 17)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 11)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 3)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 3)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
Elements     Full-text available via subscription   (Followers: 2)
Environmental Chemistry     Hybrid Journal   (Followers: 6)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 3)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 4)
Environmental Science : Nano     Partially Free   (Followers: 1)
Environmental Toxicology & Chemistry     Hybrid Journal   (Followers: 18)

        1 2 3 | Last

Journal Cover Advanced Functional Materials
  [SJR: 5.21]   [H-I: 203]   [45 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1616-301X - ISSN (Online) 1616-3028
   Published by John Wiley and Sons Homepage  [1616 journals]
  • An Ultrahigh Responsivity (9.7 mA W−1) Self-Powered Solar-Blind
           Photodetector Based on Individual ZnO–Ga2O3 Heterostructures
    • Authors: Bin Zhao; Fei Wang, Hongyu Chen, Lingxia Zheng, Longxing Su, Dongxu Zhao, Xiaosheng Fang
      Abstract: Highly crystallized ZnO–Ga2O3 core–shell heterostructure microwire is synthesized by a simple one-step chemical vapor deposition method, and constructed into a self-powered solar-blind (200–280 nm) photodetector with a sharp cutoff wavelength at 266 nm. The device shows an ultrahigh responsivity (9.7 mA W−1) at 251 nm with a high UV/visible rejection ratio (R251 nm/R400 nm) of 6.9 × 102 under zero bias. The self-powered device has a fast response speed with rise time shorter than 100 µs and decay time of 900 µs, respectively. The ultrahigh responsivity, high UV/visible rejection ratio, and fast response speed make it highly suitable in practical self-powered solar-blind detection. Additinoally, this microstructure heterojunction design method would provide a new approach to realize the high-performance self-powered photodetectors.Highly crystallized ZnO–Ga2O3 heterostructure microwire is synthesized using a simple one-step chemical vapor deposition method and the growth mechanism is discussed. A self-powered solar-blind photodetector based on individual ZnO–Ga2O3 heterostructures is demonstrated, and has responsivity as high as 9.7 mA W−1 at the wavelength of 251 nm without any external power source.
      PubDate: 2017-03-22T08:32:47.036141-05:
      DOI: 10.1002/adfm.201700264
  • Energy-Autonomous, Flexible, and Transparent Tactile Skin
    • Authors: Carlos García Núñez; William Taube Navaraj, Emre O. Polat, Ravinder Dahiya
      Abstract: Tactile or electronic skin is needed to provide critical haptic perception to robots and amputees, as well as in wearable electronics for health monitoring and wellness applications. Energy autonomy of skin is a critical feature that would enable better portability and longer operation times. This study shows a novel structure, consisting of a transparent tactile sensitive layer based on single-layer graphene, and a photovoltaic cell underneath as a building block for energy-autonomous, flexible, and tactile skin. Transparency of the touch sensitive layer is considered a key feature to allow the photovoltaic cell to effectively harvest light. Moreover, ultralow power consumed by the sensitive layer (20 nW cm−2) further reduces the photovoltaic area required to drive the tactile skin. In addition to its energy autonomy, the fabricated skin is sensitive to touch, mainly because a transparent polymeric protective layer, spin-coated on the sensor's active area, makes the coplanar capacitor sensitive to touch, detecting minimum pressures of 0.11 kPa with a uniform sensitivity of 4.3 Pa−1 along a broad pressure range. Finally, the tactile skin patches are integrated on a prosthetic hand, and the responses of the sensors for static and dynamic stimuli are evaluated by performing tasks, ranging from simple touching to grabbing of soft objects.Single-layer-graphene-based, coplanar, interdigitated capacitive touch sensors are used in this work as building blocks for a transparent, flexible, and energy-autonomous tactile skin.
      PubDate: 2017-03-22T08:27:04.517359-05:
      DOI: 10.1002/adfm.201606287
  • Masthead: (Adv. Funct. Mater. 12/2017)
    • PubDate: 2017-03-22T05:38:06.793013-05:
      DOI: 10.1002/adfm.201770074
  • Energy Storage: Ultrathin Nickel–Cobalt Phosphate 2D Nanosheets for
           Electrochemical Energy Storage under Aqueous/Solid-State Electrolyte (Adv.
           Funct. Mater. 12/2017)
    • Authors: Bing Li; Peng Gu, Yongcheng Feng, Guangxun Zhang, Kesheng Huang, Huaiguo Xue, Huan Pang
      Abstract: In article number 1605784, Huan Pang and co-workers from Yangzhou University report a mild and facile synthesis of nickel-cobalt phosphate 2D nanosheets. The growth of as-prepared materials is investigated while varying the Ni/Co ratio, solvent quantity, surface active agent, reaction temperature, and reaction time. In addition, an aqueous electrochemical energy storage device and a solid-state flexible electrochemical energy storage device are successfully assembled.
      PubDate: 2017-03-22T05:38:05.589197-05:
      DOI: 10.1002/adfm.201770073
  • One-Pot Synthesis of Dual Stimulus-Responsive Degradable Hollow Hybrid
           Nanoparticles for Image-Guided Trimodal Therapy
    • Authors: Koichiro Hayashi; Takuma Maruhashi, Michihiro Nakamura, Wataru Sakamoto, Toshinobu Yogo
      PubDate: 2017-03-22T05:38:04.584283-05:
      DOI: 10.1002/adfm.201700477
  • Transient Electronics: Dry Transient Electronic Systems by Use of
           Materials that Sublime (Adv. Funct. Mater. 12/2017)
    • Authors: Bong Hoon Kim; Jae-Hwan Kim, Luana Persano, Suk-Won Hwang, Seungmin Lee, Jungyup Lee, Yongjoon Yu, Yongseon Kang, Sang M. Won, Jahyun Koo, Youn Kyoung Cho, Gyum Hur, Anthony Banks, Jun-Kyul Song, Phillip Won, Young Min Song, Kyung-In Jang, Daeshik Kang, Chi Hwan Lee, Dario Pisignano, John A. Rogers
      Abstract: By using subliming materials, Bong Hoon Kim, John A. Rogers, and co-workers successfully design dry electronic systems that undergo timed self-destruction. As described in article number 1606008, sublimation causes mechanical fragmentation and disintegration of the devices. The concept is promising for such diverse fields as biomedical implants, environmental monitoring, and secure data systems.
      PubDate: 2017-03-22T05:38:03.625502-05:
      DOI: 10.1002/adfm.201770078
  • Energy Storage: A Lyotropic Liquid-Crystal-Based Assembly Avenue toward
           Highly Oriented Vanadium Pentoxide/Graphene Films for Flexible Energy
           Storage (Adv. Funct. Mater. 12/2017)
    • Authors: Haiqing Liu; Yanping Tang, Chi Wang, Zhixiao Xu, Chongqing Yang, Tao Huang, Fan Zhang, Dongqing Wu, Xinliang Feng
      Abstract: In article number 1606269, Haiqing Liu, Dongqing Wu, Xinliang Feng, and co-workers develop a lyotropic liquid crystal based assembly strategy to fabricate composite films of vanadium pentoxide nanobelts and graphene oxide sheets. The obtained composite films possess highly oriented layered structures, high electrical conductivity, good mechanical stability, and excellent flexibility, which allows their application as high performance electrodes in flexible energy storage devices.
      PubDate: 2017-03-22T05:38:03.141482-05:
      DOI: 10.1002/adfm.201770076
  • Tissue Engineering: Gold Nanocomposite Bioink for Printing 3D Cardiac
           Constructs (Adv. Funct. Mater. 12/2017)
    • Authors: Kai Zhu; Su Ryon Shin, Tim van Kempen, Yi-Chen Li, Vidhya Ponraj, Amir Nasajpour, Serena Mandla, Ning Hu, Xiao Liu, Jeroen Leijten, Yi-Dong Lin, Mohammad Asif Hussain, Yu Shrike Zhang, Ali Tamayol, Ali Khademhosseini
      Abstract: A novel conductive bioink containing dispersed gold nanoparticles in a photocrosslinkable hydrogel matrix is developed for microfluidic bioprinting of cardiomyocyteladen microfibrous scaffolds. As described by Su Ryon Shin, Ali Khademhosseini, and co-workers in article number 1605352, increased conductivity of the bioink leads to improved functionality of cardiomyocytes in the bioprinted patches, enabling potential applications in cardiac tissue engineering.
      PubDate: 2017-03-22T05:38:02.32536-05:0
      DOI: 10.1002/adfm.201770077
  • Contents: (Adv. Funct. Mater. 12/2017)
    • PubDate: 2017-03-22T05:38:02.198438-05:
      DOI: 10.1002/adfm.201770075
  • Flexible Electrodes: Rapid Pseudocapacitive Sodium-Ion Response Induced by
           2D Ultrathin Tin Monoxide Nanoarrays (Adv. Funct. Mater. 12/2017)
    • Authors: Minghua Chen; Dongliang Chao, Jilei Liu, Jiaxu Yan, Bowei Zhang, Yizhong Huang, Jianyi Lin, Ze Xiang Shen
      Abstract: A flexible, binder free electrode composed of 2D ultrathin (≈2.5 nm) SnO nanoflake arrays on GF/CNTs foam is described by Minghua Chen, Jianyi Lin, Ze Xiang Shen, and co-workers in article number 1606232. DFT calculations, quantitative capacitive analysis, ex-situ Raman spectroscopy, and HRTEM verify the pseudocapacitive contribution to high rate Na+ storage and long-term cycle life of sodium ion batteries.
      PubDate: 2017-03-22T05:38:00.538878-05:
      DOI: 10.1002/adfm.201770072
  • General Method for Large-Area Films of Carbon Nanomaterials and
           Application of a Self-Assembled Carbon Nanotube Film as a High-Performance
           Electrode Material for an All-Solid-State Supercapacitor
    • Authors: Li Song; Xuebo Cao, Lei Li, Qiaodi Wang, Huating Ye, Li Gu, Changjie Mao, Jiming Song, Shengyi Zhang, Helin Niu
      Abstract: Rational assembly of carbon nanostructures into large-area films is a key step to realize their applications in ubiquitous electronics and energy devices. Here, a self-assembly methodology is devised to organize diverse carbon nanostructures (nanotubes, dots, microspheres, etc.) into homogeneous films with potentially infinite lateral dimensions. On the basis of studies of the redox reactions in the systems and the structures of films, the spontaneous deposition of carbon nanostructures onto the surface of the copper substrate is found to be driven by the electrical double layer between copper and solution. As a notable example, the as-assembled multiwalled carbon nanotube (MWCNT) films display exceptional properties. They are a promising material for flexible electronics with superior electrical and mechanical compliance characteristics. Finally, two kinds of all-solid-state supercapacitors based on the self-assembled MWCNT films are fabricated. The supercapacitor using carbon cloth as the current collector delivers an energy density of 3.5 Wh kg−1 and a power density of 28.1 kW kg−1, which are comparable with the state-of-the-art supercapacitors fabricated by the costly single-walled carbon nanotubes and arrays. The supercapacitor free of foreign current collector is ultrathin and shows impressive volumetric energy density (0.58 mWh cm−3) and power density (0.39 W cm−3) too.A general methodology for the manufacture of macroscopic films of nanostructured carbon is demonstrated. The method is based on a solution assembly mechanism mediated by electrical double layer. 1D, 2D, or 3D carbon nanostructures can be organized into free-standing films with potential infinite lateral dimensions. Moreover, an all-solid-state supercapacitor fabricated using as-assembled multiwalled carbon nanotube (CNT) films exhibits performances comparable to those based on single-walled CNTs.
      PubDate: 2017-03-21T09:37:36.224345-05:
      DOI: 10.1002/adfm.201700474
  • The Contributions of Polar Nanoregions to the Dielectric and Piezoelectric
           Responses in Domain-Engineered Relaxor-PbTiO3 Crystals
    • Authors: Fei Li; Shujun Zhang, Zhuo Xu, Long-Qing Chen
      Abstract: The existence of polar nanoregions is the most important characteristic of relaxor-based ferroelectric materials. Recently, the contributions of polar nanoregions to the shear piezoelectric property of relaxor-PbTiO3 (PT) crystals are confirmed in a single domain state, accounting for 50%–80% of room temperature values. For electromechanical applications, however, the outstanding longitudinal piezoelectricity in domain-engineered relaxor-PT crystals is of the most significance. In this paper, the contributions of polar nanoregions to the longitudinal properties in [001]-poled Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 and [110]-poled Pb(Zn1/3Nb2/3)O3-0.15PbTiO3 (PZN-0.15PT) domain-engineered crystals are studied. Taking the [110]-poled tetragonal PZN-0.15PT crystal as an example, phase-field simulations of the domain structures and the longitudinal dielectric/piezoelectric responses are performed. According to the experimental results and phase-field simulations, the contributions of polar nanoregions (PNRs) to the longitudinal properties of relaxor-PT crystals are successfully explained on the mesoscale, where the PNRs behave as “seeds” to facilitate macroscopic polarization rotation and enhance electric-field-induced strain. The results reveal the importance of local structures to the macroscopic properties, where a modest structural variation on the nanoscale greatly impacts the macroscopic properties.The contributions of polar nanoregions to piezoelectric responses are successfully quantified for domain-engineered relaxor-ferroelectric crystals. A mesoscale mechanism is proposed to explain the ultrahigh longitudinal piezoelectric responses and strain behaviors of relaxor-PbTiO3 ferroelectrics, where the polar nanoregions act as “seeds” to facilitate polarization rotation and enhance the piezoelectric response.
      PubDate: 2017-03-21T09:37:25.673445-05:
      DOI: 10.1002/adfm.201700310
  • Porous Organic Field-Effect Transistors for Enhanced Chemical Sensing
    • Authors: Jingjing Lu; Dapeng Liu, Jiachen Zhou, Yingli Chu, Yantao Chen, Xiaohan Wu, Jia Huang
      Abstract: The thin-film structures of chemical sensors based on conventional organic field-effect transistors (OFETs) can limit the sensitivity of the devices toward chemical vapors, because charge carriers in OFETs are usually concentrated within a few molecular layers at the bottom of the organic semiconductor (OSC) film near the dielectric/semiconductor interface. Chemical vapor molecules have to diffuse through the OSC films before they can interact with charge carriers in the OFET conduction channel. It has been demonstrated that OFET ammonia sensors with porous OSC films can be fabricated by a simple vacuum freeze-drying template method. The resulted devices can have ammonia sensitivity not only much higher than the pristine OFETs with thin-film structure but also better than any previously reported OFET sensors, to the best of our knowledge. The porous OFETs show a relative sensitivity as high as 340% ppm−1 upon exposure to 10 parts per billion (ppb) NH3. In addition, the devices also exhibit decent selectivity and stability. This general and simple strategy can be applied to a wide range of OFET chemical sensors to improve the device sensitivity.Organic field-effect transistor (OFET)-based chemical sensors with porous film structure are fabricated by a versatile and low-cost template method. OFET chemical sensors with the porous structure exhibit much higher sensitivity than that of the pristine one. Porous OFETs exhibit obvious and reproducible response to 10 ppb NH3, with a relative sensitivity up to 340% ppm−1. The devices also show decent stability and sensing selectivity.
      PubDate: 2017-03-21T09:37:17.307748-05:
      DOI: 10.1002/adfm.201700018
  • Cell Generator: A Self-Sustaining Biohybrid System Based on Energy
           Harvesting from Engineered Cardiac Microtissues
    • Authors: Bingzhe Xu; Xudong Lin, Wei Li, Zixun Wang, Wenchong Zhang, Peng Shi
      Abstract: Biohybrid soft robotic devices present unique advantages for designing biologically active machines that can dynamically sense and interact with complex bioelectrical signals. Here, a controllable cell-based machine is developed that harvests energy from arrays of beating cardiomyocytes to generate electricity for biomedical microscale robotic applications. The “Cell Generator” device is based on an array of piezoelectric microcantilevers wrapped with 3D patterned cardiac cells. Spontaneous contraction of the engineered cardiac constructs provides the source of mechanical energy for electricity generation. It is demonstrated that a single “Cell Generator” unit with 40 cantilevers can output peak voltages of ≈70 mV, and a larger array of 540 cantilevers can directly generate a pulsed output as high as ≈1 V. When integrated with an electrical rectification and storage circuit, it is further shown that the “Cell Generator” can provide functional outputs and work as a self-powered neural stimulator to evoke action potentials in cultured neuronal networks. This demonstration of “Cell Generator” technology provides an innovative perspective of exploiting live biological powering system on biomedical microscale robotic devices in the human body.A biohybrid system—“Cell Generator”—is fabricated by patterning cardiomyocytes on arrays of microcantilevers made of piezoelectric materials. Pulsed contraction of the engineered cardiac constructs provides the source of mechanical energy for electricity generation, which is used to power biomedical devices. This technology provides an innovative perspective of exploiting live biological components for the development of self-sustaining cellular machines.
      PubDate: 2017-03-21T09:37:13.03922-05:0
      DOI: 10.1002/adfm.201606169
  • 3D Porous Cu Current Collector/Li-Metal Composite Anode for Stable
           Lithium-Metal Batteries
    • Authors: Qi Li; Shoupu Zhu, Yingying Lu
      Abstract: Lithium-metal batteries are of particular interest for next-generation electrical energy storage because of their high energy density on both volumetric and gravimetric bases. Effective strategies to stabilize the Li-metal anode are the prerequisite for the progress of these exceptional storage technologies, such as Li–S and Li–O2 batteries. Various challenges, such as uneven Li electrodeposition, anode volume expansion, and dendrite-induced short-circuit have hindered the practical application of rechargeable Li-metal batteries. Herein, a one-step facile and cost-effective strategy for stabilizing lithium-metal batteries via 3D porous Cu current collector/Li-metal composite anode is reported. The porous structure of the composite electrode provides a “cage” for the redeposition of “hostless” lithium and accommodates the anode volume expansion during cycling. Compared with planar Cu foil, its high specific surface area favors the electrochemical reaction kinetics and lowers the local current density along the anode. It leads to low interfacial resistance and stabilizes the Li electrodeposition. On this basis, galvanostatic measurements are performed on both symmetric cells and Li/Li4Ti5O12 cells and it is found that the electrodes exhibit exceptional abilities of promoting cell lifetime and stabilizing the cycling behavior. Although this work focuses on lithium metal, this novel tactic is easy to generalize to other metal electrodes.A novel 3D porous Cu current collector/Li-metal composite anode is created for high-energy lithium-metal batteries. It can stabilize the cycling behavior and improve the cell lifetime. The porous structure of the composite anode provides a “cage” for the “hostless” lithium and accommodates the anode volume expansion. Its high specific surface area favors the electrochemical reaction kinetics and lowers the local current density along the anode.
      PubDate: 2017-03-21T09:32:44.017648-05:
      DOI: 10.1002/adfm.201606422
  • Engineering of Magnetically Intercalated Silicene Compound: An Overlooked
           Polymorph of EuSi2
    • Authors: Andrey M. Tokmachev; Dmitry V. Averyanov, Igor A. Karateev, Oleg E. Parfenov, Oleg A. Kondratev, Alexander N. Taldenkov, Vyacheslav G. Storchak
      Abstract: Silicene, a Si analogue of graphene, is suggested to become a versatile material for nanoelectronics. Being coupled with magnetism, it is predicted to be particularly suitable for spintronic applications. However, experimental realization of free-standing silicene and its magnetic derivatives is lacking. Fortunately, magnetism can be induced into silicene layers, in particular, by intercalation. Here, a successful synthesis of multilayer silicene intercalated by inherently magnetic Eu ions – a compound expected to exhibit both massless Dirac-cone states, as its Ca analogue, and a nontrivial magnetic structure – is reported. This new polymorph with EuSi2 stoichiometry is epitaxially stabilized by continual replication of silicene layers employing Sr-intercalated multilayer silicene as a template. The atomic structure of the new compound and its sharp interface with the template are confirmed using electron diffraction, X-ray diffraction, and electron microscopy techniques. Below 80 K, the material demonstrates anisotropic antiferromagnetism coexisting with weak ferromagnetism. The magnetic state is accompanied by an anomalous behavior of magnetoresistivity.Multilayer silicene intercalated by magnetic Eu ions is synthesized by molecular beam epitaxy on tailor-made templates. This new polymorph of EuSi2 is the first magnetic silicene-based compound. The structure is confirmed with reflection high-energy electron diffraction, X-ray diffraction, and electron microscopy. The material exhibits anisotropic antiferromagnetism and weak ferromagnetism as well as anomalous behavior of magnetoresistivity.
      PubDate: 2017-03-21T09:26:58.393608-05:
      DOI: 10.1002/adfm.201606603
  • Environmentally Robust Black Phosphorus Nanosheets in Solution:
           Application for Self-Powered Photodetector
    • Authors: Xiaohui Ren; Zhongjun Li, Zongyu Huang, David Sang, Hui Qiao, Xiang Qi, Jianqing Li, Jianxin Zhong, Han Zhang
      Abstract: Large-size 2D black phosphorus (BP) nanosheets have been successfully synthesized by a facile liquid exfoliation method. The as-prepared BP nanosheets are used to fabricate electrodes for a self-powered photodetector and exhibit preferable photoresponse activity as well as environmental robustness. Photoelectrochemical (PEC) tests demonstrate that the current density of BP nanosheets can reach up to 265 nA cm−2 under light irradiation, while the dark current densities fluctuate near 1 nA cm−2 in 0.1 M KOH. UV–vis and Raman spectra are carried out and confirm the inherent optical and physical properties of BP nanosheets. In addition, the cycle stability measurement exhibits no detectable distinction after processing 50 and 100 cycles, while an excellent on/off behavior is still preserved even after one month. Furthermore, the PEC performance of BP nanosheets-based photodetector is evaluated in various KOH concentrations, which demonstrates that the as-prepared BP nanosheets may have a great potential application in self-powered photodetector. It is anticipated that the present work can provide fundamental acknowledgement of the performance of a PEC-type BP nanosheets-based photodetector, offering extendable availabilities for 2D BP-based heterostructures to construct high-performance PEC devices.2D black phosphorus (BP) nanosheets are fabricated as self-powered photodetector in KOH electrolyte. The photoelectrochemical tests demonstrate that BP nanosheets achieve preferable photoresponse activity as well as environmental robustness. Besides this, the photoresponse performance of BP nanosheets can be further optimized by adjusting KOH concentrations. This work presents a fundamental acknowledgement of the photoresponsivity of BP nanosheets for self-powered photodetecting.
      PubDate: 2017-03-21T09:26:44.029314-05:
      DOI: 10.1002/adfm.201606834
  • High-Energy-Density Dielectric Polymer Nanocomposites with Trilayered
    • Authors: Feihua Liu; Qi Li, Jin Cui, Zeyu Li, Guang Yang, Yang Liu, Lijie Dong, Chuanxi Xiong, Hong Wang, Qing Wang
      Abstract: The development of advanced dielectric materials with high electric energy densities is of crucial importance in modern electronics and electric power systems. Here, a new class of multilayer-structured polymer nanocomposites with high energy and power densities is presented. The outer layers of the trilayered structure are composed of boron nitride nanosheets dispersed in poly(vinylidene fluoride) (PVDF) matrix to provide high breakdown strength, while PVDF with barium strontium titanate nanowires forms the central layer to offer high dielectric constant of the resulting composites. The influence of the filler contents on the electrical polarization, breakdown strength, and energy density is examined. Simulations are carried out to model the electrical tree formation in the layered nanocomposites and to verify the experimental breakdown results. The trilayered polymer nanocomposite with an optimized filler content displays a discharged energy density of 20.5 J cm−3 at Weibull breakdown strength of 588 MV m−1, which is among the highest discharged energy densities reported so far. Moreover, the nanocomposite exhibits a superior power density of 0.91 MW cm−3, more than nine times that of the commercially available biaxially oriented polypropylene. The findings of this research provide a new design paradigm for high-performance dielectric polymer nanocomposites.Trilayered dielectric polymer nanocomposites composed of highly insulating nanosheets as the outer layers and highly polarizable nanowires as the central layer are developed to realize enhanced dielectric constant, high breakdown strength, reduced dielectric loss, and subsequently, markedly improved discharged energy densities in comparison to the conventional single-layered thin films.
      PubDate: 2017-03-21T09:26:31.834011-05:
      DOI: 10.1002/adfm.201606292
  • Multilayered Lipid Membrane Stacks for Biocatalysis Using Membrane Enzymes
    • Authors: George R. Heath; Mengqiu Li, Honling Rong, Valentin Radu, Stefan Frielingsdorf, Oliver Lenz, Julea N. Butt, Lars J. C. Jeuken
      Abstract: Multilayered or stacked lipid membranes are a common principle in biology and have various functional advantages compared to single-lipid membranes, such as their ability to spatially organize processes, compartmentalize molecules, and greatly increase surface area and hence membrane protein concentration. Here, a supramolecular assembly of a multilayered lipid membrane system is reported in which poly-l-lysine electrostatically links negatively charged lipid membranes. When suitable membrane enzymes are incorporated, either an ubiquinol oxidase (cytochrome bo3 from Escherichia coli) or an oxygen tolerant hydrogenase (the membrane-bound hydrogenase from Ralstonia eutropha), cyclic voltammetry (CV) reveals a linear increase in biocatalytic activity with each additional membrane layer. Electron transfer between the enzymes and the electrode is mediated by the quinone pool that is present in the lipid phase. Using atomic force microscopy, CV, and fluorescence microscopy it is deduced that quinones are able to diffuse between the stacked lipid membrane layers via defect sites where the lipid membranes are interconnected. This assembly is akin to that of interconnected thylakoid membranes or the folded lamella of mitochondria and has significant potential for mimicry in biotechnology applications such as energy production or biosensing.Layer-by-layer assembly of lipid bilayers is used to multiply the surface concentration of electroactive membrane enzymes at electrodes. The interconnected membrane multilayers, akin to that of thylakoid membranes, are investigated using cyclic voltammetry to reveal a linear increase in biocatalytic activity with each additional membrane layer containing a ubiquinol oxidase or an oxygen-tolerant hydrogenase.
      PubDate: 2017-03-21T07:36:05.663786-05:
      DOI: 10.1002/adfm.201606265
  • Photoluminescence Tuning in Stretchable PDMS Film Grafted Doped
           Core/Multishell Quantum Dots for Anticounterfeiting
    • Authors: Fei Li; Xiandi Wang, Zhiguo Xia, Caofeng Pan, Quanlin Liu
      Abstract: The development of new luminescent materials for anticounterfeiting is of great importance, owing to their unique physical, chemical, and optical properties. The authors report the use of color-tunable colloidal CdS/ZnS/ZnS:Mn2+/ZnS core/multishell quantum dots (QDs)-functionalized luminescent polydimethylsiloxane film (LPF) for anticounterfeiting applications. Both luminescent QDs and as-fabricated, stretchable, and transparent LPF show blue and orange emission simultaneously, which are ascribed to CdS band-edge emission and the 4T1 6A1 transition of Mn2+, respectively; their emission intensity ratios are dependent on the power-density of a single-wavelength excitation source. Additionally, photoluminescence tuning of CdS/ZnS/ZnS:Mn2+/ZnS QDs in hexane or embedded in LPF can also be realized under fixed excitation power due to a resonance energy transfer effect. Tunable photoluminescence of these flexible LPF grafted doped core/shell QDs can be finely controlled and easily realized, depending on outer excitation power and intrinsic QD concentration, which is intriguing and inspires the fabrication of many novel applications.Photoluminescence tuning of stretchable polydimethylsiloxane film grafted doped core/multishell quantum dots (QDs) can be finely controlled and easily realized depending on the outer excitation power of a single-wavelength excitation source and its intrinsic QD concentration, which is intriguing and inspires the fabrication of anticounterfeiting applications.
      PubDate: 2017-03-20T05:15:51.69347-05:0
      DOI: 10.1002/adfm.201700051
  • Novel Iron/Cobalt-Containing Polypyrrole Hydrogel-Derived Trifunctional
           Electrocatalyst for Self-Powered Overall Water Splitting
    • Authors: Jia Yang; Xu Wang, Bo Li, Liang Ma, Lei Shi, Yujie Xiong, Hangxun Xu
      Abstract: Development of efficient, low-cost, and durable electrocatalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is of significant importance for many electrochemical devices, such as rechargeable metal–air batteries, fuel cells, and water electrolyzers. Here, a novel approach for the synthesis of a trifunctional electrocatalyst derived from iron/cobalt-containing polypyrrole (PPy) hydrogel is reported. This strategy relies on the formation of a supramolecularly cross-linked PPy hydrogel that allows for efficient and homogeneous incorporation of highly active Fe/Co–N–C species. Meanwhile, Co nanoparticles are also formed and embedded into the carbon scaffold during the pyrolysis process, further promoting electrochemical activities. The resultant electrocatalyst exhibits prominent catalytic activities for ORR, OER, and HER, surpassing previously reported trifunctional electrocatalysts. Finally, it is demonstrated that the as-obtained trifunctional electrocatalyst can be used for electrocatalytic overall water splitting in a self-powered manner under ambient conditions. This work offers new prospects in developing highly active, nonprecious-metal-based electrocatalysts in electrochemical energy devices.Trifunctional electrocatalyst: A novel iron/cobalt-containing supramolecularly cross-linked polypyrrole hydrogel is developed to produce a unique electrocatalyst, which exhibits excellent activities for the oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction. Furthermore, a self-powered water-splitting device is demonstrated to stably generate H2 and O2 gases under ambient conditions.
      PubDate: 2017-03-17T07:36:18.179311-05:
      DOI: 10.1002/adfm.201606497
  • Lanthanide and Heavy Metal Free Long White Persistent Luminescence from Ti
           Doped Li–Hackmanite: A Versatile, Low-Cost Material
    • Authors: Isabella Norrbo; José M. Carvalho, Pekka Laukkanen, Jaakko Mäkelä, Fikret Mamedov, Markus Peurla, Hanna Helminen, Sari Pihlasalo, Harri Härmä, Jari Sinkkonen, Mika Lastusaari
      Abstract: Persistent luminescence (PeL) materials are used in everyday glow-in-the-dark applications and they show high potential for, e.g., medical imaging, night-vision surveillance, and enhancement of solar cells. However, the best performing materials contain rare earths and/or other heavy metal and expensive elements such as Ga and Ge, increasing the production costs. Here, (Li,Na)8Al6Si6O24(Cl,S)2:Ti, a heavy-metal- and rare-earth-free low-cost material is presented. It can give white PeL that stays 7 h above the 0.3 mcd m−2 limit and is observable for more than 100 h with a spectrometer. This is a record-long duration for white PeL and visible PeL without rare earths. The material has great potential to be applied in white light emitting devices (LEDs) combined with self-sustained night vision using only a single phosphor. The material also exhibits PeL in aqueous suspensions and is capable of showing easily detectable photoluminescence even in nanomolar concentrations, indicating potential for use as a diagnostic marker. Because it is excitable with sunlight, this material is expected to additionally be well-suited for outdoor applications.Lanthanide and heavy metal free material with long white persistent luminescence is developed from synthetic hackmanite. The material is suited for use as a single phosphor in lighting combined with emergency signage and the material shows high potential for replacing lanthanide-based label technologies. Because it is excitable with sunlight, the hackmanite material is excellent for new luminescence point-of-care detection technologies.
      PubDate: 2017-03-17T07:36:10.618719-05:
      DOI: 10.1002/adfm.201606547
  • Transparent and Robust Silica Coatings with Dual Range Porosity for
           Enzyme-Based Optical Biosensing
    • Authors: Oswaldo Pérez-Anguiano; Bernard Wenger, Raphaël Pugin, Emmanuel Scolan, Heinrich Hofmann
      Abstract: Hierarchically porous transparent silica coatings combine large specific surface area with enhanced pore accessibility for optical biosensing. This paper describes a versatile approach to fabricate optically transparent silica coatings with multiscale porosity. Thin films (around 1 μm in thickness) of an aqueous suspension of primary silica aggregates form a mesoporous, interconnected matrix, and sacrificial polymer particles template well-defined, discrete macropores with high structural integrity. The total surface area achieved is around 200 m2 g−1 with mesopore sizes of 20–40 nm and macropores of 250 nm, with a total porosity of 84%. The macro/meso dual range of porosity allows enhanced biocatalyst loadings of l-lactate dehydrogenase for detection of lactate. The functionalized films showed a linear response within the range of interest of 1–20 × 10−3m of lactate. These biosensing coatings therefore strongly enhance sensitivity, speed and reliability of optically based lactate detection as compared to classical thin films with monomodal mesopore structure. Particle-based simulations and experiments reveal that both the location and connectivity of the macropores control the biosensing performance. The coatings and procedure presented here are versatile, scalable, inexpensive, and are therefore compatible with a wide range of deposition techniques suitable for industrial and health care applications.Hierarchically porous transparent silica coatings combine large specific surface area with enhanced pore accessibility for optical biosensing with the immobilized enzyme l-lactate dehydrogenase. A dual range, interconnected porosity design with a scalable and highly robust film fabrication procedure enables fast and reliable detection of lactate, an important metabolite in medical, food, and biotechnology applications.
      PubDate: 2017-03-17T07:36:05.067651-05:
      DOI: 10.1002/adfm.201606385
  • Significantly Increased Raman Enhancement on MoX2 (X = S, Se) Monolayers
           upon Phase Transition
    • Authors: Ying Yin; Peng Miao, Yumin Zhang, Jiecai Han, Xinghong Zhang, Yue Gong, Lin Gu, Chengyan Xu, Tai Yao, Ping Xu, Yi Wang, Bo Song, Song Jin
      Abstract: 2D transition metal dichalcogenide (TMD) materials have been recognized as active platforms for surface-enhanced Raman spectroscopy (SERS). Here, the effect of crystal structure (phase) transition is shown, which leads to altered electronic structures of TMD materials, on the Raman enhancement. Using thermally evaporated copper phthalocyanine, solution soaked rhodamine 6G, and crystal violet as typical probe molecules, it is found that a phase transition from 2H- to 1T-phase can significantly increase the Raman enhancement effect on MoX2 (X = S, Se) monolayers through a predominantly chemical mechanism. First-principle density functional theory calculations indicate that the significant enhancement of the Raman signals on metallic 1T-MoX2 can be attributed to the facilitated electron transfer from the Fermi energy level of metallic 1T-MoX2 to the highest occupied molecular orbital level of the probe molecules, which is more efficient than the process from the top of valence band of semiconducting 2H-MoX2. This study not only reveals the origin of the Raman enhancement and identifies 1T-MoSe2 and 1T-MoS2 as potential Raman enhancement substrates, but also paves the way for designing new 2D SERS substrates via phase-transition engineering.A phase transition induced Raman enhancement is demonstrated on MoX2 (X = S, Se) monolayer substrates. It is found to be due to the highly efficient charge transfer from the Fermi energy level of 1T-MoX2 to the highest occupied molecular orbital level of the probe molecule. These novel features of 1T-MoX2 may provide a new approach for the development of new type 2D surface-enhanced Raman spectroscopy substrates.
      PubDate: 2017-03-17T07:35:30.679685-05:
      DOI: 10.1002/adfm.201606694
  • N-, O-, and S-Tridoped Carbon-Encapsulated Co9S8 Nanomaterials: Efficient
           Bifunctional Electrocatalysts for Overall Water Splitting
    • Authors: Senchuan Huang; Yuying Meng, Shiman He, Anandarup Goswami, Qili Wu, Junhao Li, Shengfu Tong, Tewodros Asefa, Mingmei Wu
      Abstract: The development of highly active and stable earth-abundant catalysts to reduce or eliminate the reliance on noble-metal based ones in green and sustainable (electro)chemical processes is nowadays of great interest. Here, N-, O-, and S-tridoped carbon-encapsulated Co9S8 (Co9S8@NOSC) nanomaterials are synthesized via simple pyrolysis of S- and Co(II)-containing polypyrrole solid precursors, and the materials are proven to serve as noble metal-free bifunctional electrocatalysts for water splitting in alkaline medium. The nanomaterials exhibit remarkable catalytic performances for oxygen evolution reaction in basic electrolyte, with small overpotentials, high anodic current densities, low Tafel slopes as well as very high (nearly 100%) Faradic efficiencies. Moreover, the materials are found to efficiently electrocatalyze hydrogen evolution reaction in acidic as well as basic solutions, showing high activity in both cases and maintaining good stability in alkaline medium. A two-electrode electrolyzer assembled using the material synthesized at 900 °C (Co9S8@NOSC-900) as an electrocatalyst at both electrodes gives current densities of 10 and 20 mA cm−2 at potentials of 1.60 and 1.74 V, respectively. The excellent electrocatalytic activity exhibited by the materials is proposed to be mainly due to the synergistic effects between the Co9S8 nanoparticles cores and the heteroatom-doped carbon shells in the materials.N, O, and O tri-doped carbon encapsulated Co9S8 nanomaterials are successfully synthesized and serve as efficient noble metal-free bifunctional electrocatalysts for alkali water splitting with remarkable catalytic performance. The two-electrode electrolyzer assembled using the Co9S8@NOSC-900 material as electrocatalyst at both the anode and the cathode electrodes gives current densities of 10 and 20 mA cm−2 at potentials of 1.60 and 1.74 V, respectively.
      PubDate: 2017-03-17T07:30:40.24218-05:0
      DOI: 10.1002/adfm.201606585
  • From Smart Denpols to Remote-Controllable Actuators: Hierarchical
           Superstructures of Azobenzene-Based Polynorbornenes
    • Authors: Dae-Yoon Kim; Suyong Shin, Won-Jin Yoon, Yu-Jin Choi, Joo-Kyoung Hwang, Jin-Soo Kim, Cheul-Ro Lee, Tae-Lim Choi, Kwang-Un Jeong
      Abstract: For the demonstration of remote-controllable actuators, a dendronized polymer (denpol) is newly designed and successfully synthesized by ring-opening metathesis polymerization of azobenzene-based macromonomers. The incorporation of azobenzene mesogens into the denpols helps to construct finely tuned hierarchical superstructures with anisotropic physical properties and reversible photoisomerization. The polynorbornene backbones and azobenzene side chains in the uniaxially oriented films are aligned perpendicularly and parallel to the layer normal, respectively. Based on photoreversible actuation experiments combined with diffraction results, direct relationships between the chemical structures, hierarchical superstructures, and their corresponding photomechanical behaviors are proposed. Smart denpols possess great potential for practical applications in photoresponsive switches.To demonstrate remote-controllable actuators, a polynorbornene with dendronized azobenzene chromophores is synthesized by ring-opening metathesis polymerization.
      PubDate: 2017-03-17T07:30:34.419165-05:
      DOI: 10.1002/adfm.201606294
  • Reusable Cellulose-Based Hydrogel Sticker Film Applied as Gate Dielectric
           in Paper Electrolyte-Gated Transistors
    • Authors: Inês Cunha; Raquel Barras, Paul Grey, Diana Gaspar, Elvira Fortunato, Rodrigo Martins, Luís Pereira
      Abstract: A new concept for reusable eco-friendly hydrogel electrolytes based on cellulose is introduced. The reported electrolytes are designed and engineered through a simple, fast, low-cost, and eco-friendly dissolution method of microcrystalline cellulose at low temperature using an aqueous LiOH/urea solvent system. The cellulose solution is combined with carboxymethyl cellulose, followed by the regeneration and simultaneous ion incorporation. The produced free standing cellulose-based electrolyte films exhibit interesting properties for application in flexible electrochemical devices, such as biosensors or electrolyte-gated transistors (EGTs), because of their high specific capacitances (4–5 µF cm−2), transparency, and flexibility. Indium–gallium–zinc-oxide EGTs on glass with laminated cellulose-based hydrogel electrolytes (CHEs) as the gate dielectric are produced presenting a low working voltage (
      PubDate: 2017-03-17T07:15:34.345893-05:
      DOI: 10.1002/adfm.201606755
  • Scrutinizing Design Principles toward Efficient, Long-Term Stable Green
           Light-Emitting Electrochemical Cells
    • Authors: Jude E. Namanga; Niels Gerlitzki, Anja-Verena Mudring
      Abstract: Enhancing the efficiency and lifetime of light emitting electrochemical cells (LEC) is the most important challenge on the way to energy efficient lighting devices of the future. To avail this, emissive Ir(III) complexes with fluoro-substituted cyclometallated ligands and electron donating groups (methyl and tert-butyl)-substituted diimine ancillary (N^N) ligands and their associated LEC devices are studied. Four different complexes of general composition [Ir(4ppy)2(N^N)][PF6] (4Fppy = 2-(4-fluorophenyl)pyridine) with the N^N ligand being either 2,2′-bipyridine (1), 4.4′-dimethyl-2,2′-bipyridine (2), 5.5′-dimethyl-2,2′-bipyridine (3), or 4.4′-di-tert-butyl-2,2′-bipyridine (4) are synthesized and characterized. All complexes emit in the green region of light with emission maxima of 529–547 nm and photoluminescence quantum yields in the range of 50.6%–59.9%. LECs for electroluminescence studies are fabricated based on these complexes. The LEC based on (1) driven under pulsed current mode demonstrated the best performance, reaching a maximum luminance of 1605 cd m−2 resulting in 16 cd A−1 and 8.6 lm W−1 for current and power efficiency, respectively, and device lifetime of 668 h. Compared to this, LECs based on (3) and (4) perform lower, with luminance and lifetime of 1314 cd m−2, 45.7 h and 1193 cd m−2, 54.9 h, respectively. Interestingly, in contrast to common belief, the fluorine content of the Ir-iTMCs does not adversely affect the LEC performance, but rather electron donating substituents on the N^N ligands are found to dramatically reduce both performance and stability of the green LECs. In light of this, design concepts for green light emitting electrochemical devices have to be reconsidered.A green light emitting electrochemical cell (LEC) with unprecedented performance has been achieved by carefully examining the emitter design principles and driving conditions for efficient and long-term stable LECs. In light of the current findings, the commonly accepted design guidelines have to be revised.
      PubDate: 2017-03-16T10:06:12.494707-05:
      DOI: 10.1002/adfm.201605588
  • Self-Powered Electrostatic Actuation Systems for Manipulating the Movement
    • Authors: Li Zheng; Yali Wu, Xiangyu Chen, Aifang Yu, Liang Xu, Yongsheng Liu, Hexing Li, Zhong Lin Wang
      Abstract: By integrating a triboelectric nanogenerator (TENG) and an electrostatic actuation system (EAS), two kinds of self-powered EAS are designed for manipulating the movement of both microfluid and tiny solid objects. The mechanical triggering of the TENG can generate an extremely high electrostatic field inside EAS and thus the tiny object (liquid or solid) in the EAS can be actuated by the Coulomb force. Accordingly, the tribomotion of TENG can be used as both the driving power and control signal for the EAS. The TENG device with a contact surface of 70 cm2 can drive a water droplet to move across a gap of 2 cm. Meanwhile, the confluence of two droplets with the same charge polarity and different components can also be induced and controlled by this self-powered EAS. In addition, based on the same working principle, this EAS also demonstrates its capability for manipulating solid object (e.g., a tiny steel pellet). By sliding the Kapton film along a segmented annular electrode, the tiny pellet can well follow the rotated motion of the Kapton film. The demonstrated concept of this self-powered EAS has excellent applicability for various micro/miniature actuation devices, electromechanical systems, human–machine interaction, etc.By integrating a triboelectric nanogenerator (TENG) and an electrostatic actuation system, the authors have demonstrated a concept of self-powered actuation system and the tiny liquid/solid objects, which cannot be easily activated by common mechanical tools, can possibly be accurately manipulated only by simple manual operations imposed on TENG devices. Here, the motion of TENG can serve as both driving power and regulating signal, and thus no power source or sophisticated control circuits is needed for this system.
      PubDate: 2017-03-15T08:26:03.521051-05:
      DOI: 10.1002/adfm.201606408
  • Recent Advances in Sensing Applications of Two-Dimensional Transition
           Metal Dichalcogenide Nanosheets and Their Composites
    • Authors: Jianfeng Ping; Zhanxi Fan, Melinda Sindoro, Yibin Ying, Hua Zhang
      Abstract: Two-dimensional (2D) transition metal dichalcogenide (TMD) nanosheets, such as MoS2, WS2, etc., are attracting increasing interest due to their intriguing physical, chemical, electronic, and optical properties. Success in development of methods for large-scale production of 2D TMD nanosheets and their composites has given great potential for various novel applications. In this review, recent progress in sensing applications of 2D TMD nanosheets and their composites is introduced. Moreover, different sensing strategies and signal-transducing mechanisms for sensing devices based on 2D TMD nanosheets and their composites are also summarized and discussed.Two-dimensional layered transition metal dichalcogenide nanosheets have attracted extensive attention recently. Here, a comprehensive review on emerging applications of transition metal dichalcogenide nanosheets and their composites in sensing devices is presented, with a focus on signal transducing mechanisms and sensing strategies. Furthermore, current challenges and future prospects in this field are included to provide an overview of future research directions.
      PubDate: 2017-03-15T08:25:49.50559-05:0
      DOI: 10.1002/adfm.201605817
  • Identifying the Conversion Mechanism of NiCo2O4 during
           Sodiation–Desodiation Cycling by In Situ TEM
    • Authors: Chongyang Zhu; Feng Xu, Huihua Min, Yuan Huang, Weiwei Xia, Yuanting Wang, Qingyu Xu, Peng Gao, Litao Sun
      Abstract: For alkali metal ion batteries, probing the ion storage mechanism (intercalation- or conversion-type) and concomitant phase evolution during sodiation–desodiation cycling is critical to gain insights into understanding how the electrode functions and thus how it can be improved. Here, by using in situ transmission electron microscopy, the whole sodiation–desodiation process of spinel NiCo2O4 nanorods is tracked in real time. Upon the first sodiation, a two-step conversion reaction mechanism has been revealed: NiCo2O4 is first converted into intermediate phases of CoO and NiO that are then further reduced to Co and Ni phases. Upon the first desodiation, Co and Ni cannot be recovered to original NiCo2O4 phase, and divalent metal oxides of CoO and NiO are identified as desodiated products for the first time. Such asymmetric conversion reactions account for the huge capacity loss during the first charging–discharging cycle of NiCo2O4-based sodium-ion batteries (SIBs). Impressively, a reversible and symmetric phase transformation between CoO/Co and NiO/Ni phases is established during subsequent sodiation–desodiation cycles. This work provides valuable insights into mechanistic understanding of phase evolution during sodiation–desodiation of NiCo2O4, with the hope of assistance in designing SIBs with improved performance.In situtransmission electron microscopy is used to reveal the whole sodiation–desodiation cycling of spinel NiCo2O4 in real time. Two-step phase change during the first sodiation and irreversible conversion reaction during the first desodiation have been identified. Moreover, a reversible and symmetric phase transformation between CoO/Co and NiO/Ni phases is established during subsequent sodiation–desodiation cycles.
      PubDate: 2017-03-15T08:21:34.339858-05:
      DOI: 10.1002/adfm.201606163
  • A New Strategy to Effectively Suppress the Initial Capacity Fading of Iron
           Oxides by Reacting with LiBH4
    • Authors: Yun Cao; Yaxiong Yang, Zhuanghe Ren, Ni Jian, Mingxia Gao, Yongjun Wu, Min Zhu, Feng Pan, Yongfeng Liu, Hongge Pan
      Abstract: In this work, a new facile and scalable strategy to effectively suppress the initial capacity fading of iron oxides is demonstrated by reacting with lithium borohydride (LiBH4) to form a B-containing nanocomposite. Multielement, multiphase B-containing iron oxide nanocomposites are successfully prepared by ball-milling Fe2O3 with LiBH4, followed by a thermochemical reaction at 25–350 °C. The resulting products exhibit a remarkably superior electrochemical performance as anode materials for Li-ion batteries (LIBs), including a high reversible capacity, good rate capability, and long cycling durability. When cycling is conducted at 100 mA g−1, the sample prepared from Fe2O3–0.2LiBH4 delivers an initial discharge capacity of 1387 mAh g−1. After 200 cycles, the reversible capacity remains at 1148 mAh g−1, which is significantly higher than that of pristine Fe2O3 (525 mAh g−1) and Fe3O4 (552 mAh g−1). At 2000 mA g−1, a reversible capacity as high as 660 mAh g−1 is obtained for the B-containing nanocomposite. The remarkably improved electrochemical lithium storage performance can mainly be attributed to the enhanced surface reactivity, increased Li+ ion diffusivity, stabilized solid-electrolyte interphase (SEI) film, and depressed particle pulverization and fracture, as measured by a series of compositional, structural, and electrochemical techniques.A boron-containing iron oxide nanocomposite is successfully synthesized by ball milling mixtures of Fe2O3–xLiBH4 and subsequently heating to 350 °C. The prepared B-containing iron oxide composites exhibit remarkably superior electrochemical performance as anode materials for Li-ion batteries, including high reversible capacity, good rate capability, and long cycling durability.
      PubDate: 2017-03-15T08:21:14.17148-05:0
      DOI: 10.1002/adfm.201700342
  • Ions Matter: Description of the Anomalous Electronic Behavior in
           Methylammonium Lead Halide Perovskite Devices
    • Authors: Onkar S. Game; Gabriel J. Buchsbaum, Yuanyuan Zhou, Nitin P. Padture, Angus I. Kingon
      Abstract: Carrier transport in methylammonium lead iodide (MAPbI3)-based hybrid organic–inorganic perovskites (HOIPs) is obscured by vacancy-mediated ion migration. Thus, the nature of migrating species (cation/anion) and their effect on electronic transport in MAPbI3 has remained controversial. Temperature-dependent pulsed voltage–current measurements of MAPbI3 thin films are performed under dark conditions, designed to decouple ion-migration/accumulation and electronic transport. Measurement conditions (electric-field history and scan rate) are shown to affect the electronic transport in MAPbI3 thin films, through a mechanism involving ion migration and accumulation at the electrode interfaces. The presence of thermally activated processes with distinct activation energies (Ea) of 0.1 ± 0.001 and 0.41 ± 0.02 eV is established, and are assigned to electromigration of iodine vacancies and methylammonium vacancies, respectively. Analysis of activation energies obtained from electronic conduction versus capacitive discharge shows that the electromigration of these ionic species is responsible for the modification of interfacial electronic properties of MAPbI3, and elaborates previously unaddressed issues of “fast” and “slow” ion migration. The results demonstrate that the intrinsic behavior of MAPbI3 material is responsible for the hysteresis of the solar cells, but also have implications for other HOIP-based devices, such as memristors, detectors, and energy storage devices.It is demonstrated that hybrid perovskite (MAPbI3)-based M–S–M devices show I–V anomalies (hysteresis and field/scan rate dependent dynamic rectification) even under dark conditions. Using temperature-dependent pulsed current–voltage measurements, the origin of such I–V anomalies in migration and accumulation of two ionic species with different activation energies (0.1 and 0.41 eV) is established.
      PubDate: 2017-03-15T08:21:03.846504-05:
      DOI: 10.1002/adfm.201606584
  • Thickness Dependent Properties in Oxide Heterostructures Driven by
           Structurally Induced Metal–Oxygen Hybridization Variations
    • Authors: Zhaoliang Liao; Nicolas Gauquelin, Robert J. Green, Sebastian Macke, Julie Gonnissen, Sean Thomas, Zhicheng Zhong, Lin Li, Liang Si, Sandra Van Aert, Philipp Hansmann, Karsten Held, Jing Xia, Johan Verbeeck, Gustaaf Van Tendeloo, George A. Sawatzky, Gertjan Koster, Mark Huijben, Guus Rijnders
      Abstract: Thickness-driven electronic phase transitions are broadly observed in different types of functional perovskite heterostructures. However, uncertainty remains whether these effects are solely due to spatial confinement, broken symmetry, or rather to a change of structure with varying film thickness. Here, this study presents direct evidence for the relaxation of oxygen-2p and Mn-3d orbital (p–d) hybridization coupled to the layer-dependent octahedral tilts within a La2/3Sr1/3MnO3 film driven by interfacial octahedral coupling. An enhanced Curie temperature is achieved by reducing the octahedral tilting via interface structure engineering. Atomically resolved lattice, electronic, and magnetic structures together with X-ray absorption spectroscopy demonstrate the central role of thickness-dependent p–d hybridization in the widely observed dimensionality effects present in correlated oxide heterostructures.Relaxation of oxygen-2p and Mn-3d orbital (p–d) hybridization is coupled to the layer-dependent octahedral tilts within a La2/3Sr1/3MnO3 film driven by interfacial octahedral coupling. Enhanced Curie temperatures are achieved by reducing the octahedral tilting via interface structure engineering, demonstrating the central role of thickness-dependent p–d hybridization in widely observed dimensionality effects present in correlated oxide heterostructures.
      PubDate: 2017-03-15T08:20:57.944715-05:
      DOI: 10.1002/adfm.201606717
  • Chemically Resistant, Shapeable, and Conducting Metal-Organic Gels and
           Aerogels Built from Dithiooxamidato Ligand
    • Authors: Daniel Vallejo-Sánchez; Pilar Amo-Ochoa, Garikoitz Beobide, Oscar Castillo, Michael Fröba, Frank Hoffmann, Antonio Luque, Pilar Ocón, Sonia Pérez-Yáñez
      Abstract: Metal-organic gels (MOGs) appear as a blooming alternative to well-known metal-organic frameworks (MOFs). Porosity of MOGs has a microstructural origin and not strictly crystalline like in MOFs; therefore, gelation may provide porosity to any metal-organic system, including those with interesting properties but without a porous crystalline structure. The easy and straightforward shaping of MOGs contrasts with the need of binders for MOFs. In this contribution, a series of MOGs based on the assembly of 1D-coordination polymer nanofibers of formula [M(DTA)]n (MII: Ni, Cu, Pd; DTA: dithiooxamidato) are reported, in which properties such as porosity, chemical inertness, mechanical robustness, and stimuli-responsive electrical conductivity are brought together. The strength of the MS bond confers an unusual chemical resistance, withstanding exposure to acids, alkalis, and mild oxidizing/reducing chemicals. Supercritical drying of MOGs provides ultralight metal-organic aerogels (MOAs) with densities as low as 0.03 g cm−3 and plastic/brittle behavior depending on the nanofiber aspect ratio. Conductivity measurements reveal a semiconducting behavior (10−12 to 10−7 S cm−1 at 298 K) that can be improved by doping (10−5 S cm−1). Moreover, it must be stressed that conductivity of MOAs reversibly increases (up to 10−5 S cm−1) under the presence of acetic acid.A series of metal-organic gels and aerogels based on the assembly of 1D-coordination polymer nanofibers of formula [M(DTA)]n (MII: Ni, Cu, Pd; DTA: dithiooxamidato) are reported, in which properties such as porosity, chemical inertness, mechanical robustness, and stimuli-responsive electrical conductivity are brought together into an unprecedented material. Gelation approach provides a valuable tool to achieve metal-organic mesoporous materials.
      PubDate: 2017-03-10T10:49:29.256565-05:
      DOI: 10.1002/adfm.201605448
  • Mesh-on-Mesh Graphitic-C3N4@Graphene for Highly Efficient Hydrogen
    • Authors: Qing Han; Zhihua Cheng, Jian Gao, Yang Zhao, Zhipan Zhang, Liming Dai, Liangti Qu
      Abstract: Mesoporous materials have attracted considerable interest due to their huge surface areas and numerous active sites that can be effectively exploited in catalysis. Here, 2D mesoporous graphitic-C3N4 nanolayers are rationally assembled on 2D mesoporous graphene sheets (g-CN@G MMs) by in situ selective growth. Benefiting from an abundance of exposed edges and rich defects, fast electron transport, and a multipathway of charge and mass transport from a continuous interconnected mesh network, the mesh-on-mesh g-CN@G MMs hybrid exhibits higher catalytic hydrogen evolution activity and stronger durability than most of the reported nonmetal catalysts and some metal-based catalysts.A dual-mesh hybrid foam of in situ selectively-formed 2D mesoporous graphitic-C3N4 mesh with 2D mesoporous N-doped graphene mesh has been prepared. As a new type of nonmetal electrocatalyst, it's unique pore-hierarchical architecture exhibits excellent electrocatalytic activity and robust durability, superior to most nonmetal materials and even better than some non-noble metallic catalysts.
      PubDate: 2017-03-10T10:46:06.766045-05:
      DOI: 10.1002/adfm.201606352
  • Nanoscale Defect Engineering and the Resulting Effects on Domain Wall
           Dynamics in Ferroelectric Thin Films
    • Authors: Leo J. McGilly; Cosmin S. Sandu, Ludwig Feigl, Dragan Damjanovic, Nava Setter
      Abstract: Defect engineering is one of the cornerstones of the modern electronics industry. Almost all electronic devices include materials that have been doped by ion bombardment. For materials where crystallinity is essential, such as ferroelectrics, defect type and concentration can vastly influence properties and are often used to optimize device performance. This study shows a method to effectively control the density and position on the nanoscale of defect sites in thin films of Pb(Zr,Ti)O3 via focused ion beam microscopy. This allows for exceptional clarity of observation of the role of defects in nucleation, polarization switching, and domain wall interaction through investigation with piezoresponse force microscopy and transmission electron microscopy, adding insight to accepted but seldom-demonstrated facts on defect-induced effects. This nanoscale defect engineering can be used as a tool to control material properties, and furthermore, a route is demonstrated toward a practical application.Low-dose Ga+ ion beams are used to effectively control the density and position on the nanoscale of defect sites in thin films of Pb(Zr,Ti)O3 via focused ion beam microscopy. This allows for clear observation of the role of defects in nucleation, polarization switching, and domain wall interaction through investigation with piezoresponse force microscopy and transmission electron microscopy.
      PubDate: 2017-03-10T10:45:53.741944-05:
      DOI: 10.1002/adfm.201605196
  • The Effect of H- and J-Aggregation on the Photophysical and Photovoltaic
           Properties of Small Thiophene–Pyridine–DPP Molecules for
           Bulk-Heterojunction Solar Cells
    • Authors: Miriam Más-Montoya; René A. J. Janssen
      Abstract: The performance of organic semiconductors in optoelectronic devices depends on the functional properties of the individual molecules and their mutual orientations when they are in the solid state. The effect of H- and J-aggregation on the photophysical properties and photovoltaic behavior of four electronically identical but structurally different thiophene–pyridine–diketopyrrolopyrrole molecules is studied. By introducing and changing the position of two hexyl side chains on the two peripheral thiophene units of these molecules, their aggregation in thin films between H-type and J-type is effectively tuned, as evidenced from the characteristics of optical absorption, fluorescence, and excited state lifetime. The two derivatives that assemble into J-type aggregates exhibit a significantly enhanced photovoltaic performance, up to an order of magnitude, compared to the two molecules that form H-type aggregates. The reasons for this remarkably different behavior are discussed.The aggregation behavior of electronically identical thiophene–pyridine–diketopyrrolopyrrole molecules is modulated by introducing and modifying the position of two hexyl side chains on the peripheral thiophene rings. Improved photovoltaic performance is achieved for those molecules assembling into J-type aggregates in contrast to those forming H-aggregates as a result of a faster charge generation and a reduced bimolecular recombination.
      PubDate: 2017-03-10T10:45:48.371311-05:
      DOI: 10.1002/adfm.201605779
  • Fabricating Aptamer-Conjugated PEGylated-MoS2/Cu1.8S Theranostic
           Nanoplatform for Multiplexed Imaging Diagnosis and Chemo-Photothermal
           Therapy of Cancer
    • Authors: Xiangdan Meng; Zhiqiang Liu, Yu Cao, Wenhao Dai, Kai Zhang, Haifeng Dong, Xiaoyan Feng, Xueji Zhang
      Abstract: Fabricating theranostic nanoparticles combining multimode disease diagnosis and therapeutic has become an emerging approach for personal nanomedicine. However, the diagnostic capability, biocompatibility, and therapeutic efficiency of theranostic nanoplatforms limit their clinic widespread applications. Targeting to the theme of accurate diagnosis and effective therapy of cancer cells, a multifunctional nanoplatform of aptamer and polyethylene glycol (PEG) conjugated MoS2 nanosheets decorated with Cu1.8S nanoparticles (ATPMC) is developed. The ATPMC nanoplatform accomplishes photoluminescence imaging, photoacoustic imaging, and photothermal imaging for in vitro and in vivo tumor cells imaging diagnosis. Meanwhile, the ATPMC nanoplatform facilitates selective delivery of gene probe to detect intracellular microRNA aberrantly expressed in cancer cells and anticancer drug doxorubicin (DOX) for chemotherapy. Moreover, the synergistic interaction of MoS2 and Cu1.8S renders the ATPMC nanoplatform with superb photothermal conversion efficiency. The ATPMC nanoplatform loaded with DOX displays near-infrared laser-induced programmed chemotherapy and advanced photothermal therapy, and the targeted chemo-photothermal therapy presents excellent antitumor efficiency.An aptamer-conjugated PEGylated-MoS2/Cu1.8S (ATPMC) theranostic nanoplatform is fabricated. It integrates photoluminescence imaging, photoacoustic imaging, and photothermal imaging for in vitro and in vivo tumor cells imaging diagnosis. The ATPMC loaded with doxorubicin presents advanced photothermal therapy and targeted programmed chemotherapy, which possesses excellent therapeutic efficiency of cancer cells treatment.
      PubDate: 2017-03-10T10:45:23.026396-05:
      DOI: 10.1002/adfm.201605592
  • Intracellularly Disintegratable Polysulfoniums for Efficient Gene Delivery
    • Authors: Dingcheng Zhu; Huijie Yan, Xin Liu, Jiajia Xiang, Zhuxian Zhou, Jianbin Tang, Xiangrui Liu, Youqing Shen
      Abstract: Amine-based cationic polymers have been extensively explored as nonviral carriers for gene delivery, but inefficient intracellular unpacking of polymer/DNA complexes (polyplexes) to release plasmids is still a key limiting step to high transfection efficiency. Furthermore, the amine-resulting cationic charges in the polymer chains, and even their degraded fragments, inherently interfere with transgene expression. A cationic polymer capable of converting to uncharged fragments once inside cells would not only quickly release the DNA, but also not interfere with the gene transcription process for efficient gene expression and low toxicity. A new class of polysulfoniums that can degrade into neutral thioether fragments triggered by reactive oxygen species (ROS) is reported. The polysulfoniums condense DNA into nanosized polyplexes, which can be quickly internalized and efficiently escape from endo/lysosomes. In cancer cells, the oxidation of the boronic acid/ester by the elevated ROS levels triggers polysulfonium to break down into neutral thioether fragments, efficiently releasing DNA for gene expression. More importantly, the polyplexes have excellent serum resistance; in vivo, they efficiently deliver the suicide gene pTRAIL to intraperitoneal tumors eliciting effective anticancer activity.We report a new class of reactive oxygen species (ROS)-responsive main-chain-disintegrable polysulfoniums, which respond to the elevated intracellular ROS and degrade into neutral thioether fragments. They can not only quickly release the carried DNA but also avoid interference with the gene transcription process, leading to efficient gene expression and low toxicity.
      PubDate: 2017-03-10T10:45:02.817303-05:
      DOI: 10.1002/adfm.201606826
  • In Vivo Examination of an Injectable Hydrogel System Crosslinked by
           Peptide–Oligosaccharide Interaction in Immunocompetent Nude Mice
    • Authors: Christoph Tondera; Robert Wieduwild, Elisabeth Röder, Carsten Werner, Yixin Zhang, Jens Pietzsch
      Abstract: Hydrogels can serve as matrices to mimic natural tissue function and be used for wide-ranging applications such as tissue regeneration and drug delivery. Injectable hydrogels are particularly favorable because their uses are minimally invasive. However, creating moldable substance for injection often results in compromised function and stability. This study reports an injectable hydrogel system crosslinked by peptide–oligosaccharide noncovalent interaction. The dynamic network shows fast self-healing, a property essential for injectability. Injected hydrogels in immunocompetent mice and release of encapsulated compound are monitored up to 9 months by magnetic resonance imaging (MRI) and optical imaging. This surprisingly stable hydrogel does not cause adverse inflammatory response, as analyzed by measuring cytokine levels, immunohistochemistry, and MRI. Hydrogel degradation is associated with invasion of macrophages and vascular formation. The facile synthesis, high biocompatibility, and stability of this injectable hydrogel can lead to various experimental and clinical applications in regenerative medicine and drug delivery.A hydrogel system crosslinked by peptide–oligosaccharide noncovalent interaction exhibits fast self-healing and injectability. Injected hydrogels in immunocompetent mice and release of encapsulated compound are monitored up to 9 months by magnetic resonance imaging and optical imaging. This surprisingly stable hydrogel does not cause adverse inflammatory response, while its degradation is associated with invasion of macrophages and vascular formation.
      PubDate: 2017-03-09T02:15:49.540547-05:
      DOI: 10.1002/adfm.201605189
  • Concurrent Synthesis of High-Performance Monolayer Transition Metal
    • Authors: Linfeng Sun; Wei Sun Leong, Shize Yang, Matthew F. Chisholm, Shi-Jun Liang, Lay Kee Ang, Yongjian Tang, Yunwei Mao, Jing Kong, Hui Ying Yang
      Abstract: To data, the chemical vapor deposition (CVD) approach has been widely used for the growth of transition metal dichalcogenides (TMDs). However, the reported CVD methods to synthesize TMDs cannot be used to grow more than one type of TMDs. This work reports a promising CVD technique to concurrently synthesize multiple monolayer transition metal disulfides once. The optoelectrical characterization and high-resolution transmission electron microscopy show the high quality of monolayer crystals, and, more importantly, there is no mixing between different precursors during the growth process, which has been investigated by considering the gas flow dynamics and concentration distribution of precursors in our setup. This strategy indicates the promising future for the batch production of 2D materials and the concurrent synthesis techniques in standard state-of-the-art complementary metal-oxide-semiconductor (CMOS) fabrication technology.The batch production of monolayer MoS2 and its derivatives grown by chemical vapor deposition techniques has been demonstrated. The concurrent synthesis of different 2D materials is also carried out with a uniform crystal quality and high mobility at 64 cm2 V−1 s−1 (room temperature).
      PubDate: 2017-03-09T02:15:40.848843-05:
      DOI: 10.1002/adfm.201605896
  • Inorganic Rubidium Cation as an Enhancer for Photovoltaic Performance and
           Moisture Stability of HC(NH2)2PbI3 Perovskite Solar Cells
    • Authors: Yun Hee Park; Inyoung Jeong, Seunghwan Bae, Hae Jung Son, Phillip Lee, Jinwoo Lee, Chul-Ho Lee, Min Jae Ko
      Abstract: Perovskite solar cells (PSCs) based on organic monovalent cation (methylammonium or formamidinium) have shown excellent optoelectronic properties with high efficiencies above 22%, threatening the status of silicon solar cells. However, critical issues of long-term stability have to be solved for commercialization. The severe weakness of the state-of-the-art PSCs against moisture originates mainly from the hygroscopic organic cations. Here, rubidium (Rb) is suggested as a promising candidate for an inorganic–organic mixed cation system to enhance moisture-tolerance and photovoltaic performances of formamidinium lead iodide (FAPbI3). Partial incorporation of Rb in FAPbI3 tunes the tolerance factor and stabilizes the photoactive perovskite structure. Phase conversion from hexagonal yellow FAPbI3 to trigonal black FAPbI3 becomes favored when Rb is introduced. The authors find that the absorbance and fluorescence lifetime of 5% Rb-incorporated FAPbI3 (Rb0.05FA0.95PbI3) are enhanced than bare FAPbI3. Rb0.05FA0.95PbI3-based PSCs exhibit a best power conversion efficiency of 17.16%, which is much higher than that of the FAPbI3 device (13.56%). Moreover, it is demonstrated that the Rb0.05FA0.95PbI3 film shows superior stability against high humidity (85%) and the full device made with the mixed perovskite exhibits remarkable long-term stability under ambient condition without encapsulation, retaining the high performance for 1000 h.Partial substitution of inorganic rubidium cation (Rb+) for formamidinium lead iodide (FAPbI3) perovskite suppresses nonperovskite phase formation and increases fluorescence lifetime. Introduction of the smaller monovalent cation in FAPbI3 renders the perovskite more tolerant to high humidity. These lead to enhanced photovoltaic performances and long-term stability of perovskite solar cells based on Rb-mixed FAPbI3.
      PubDate: 2017-03-09T02:10:59.157635-05:
      DOI: 10.1002/adfm.201605988
  • Functionalized Graphene as Extracellular Matrix Mimics: Toward
           Well-Defined 2D Nanomaterials for Multivalent Virus Interactions
    • Authors: Mohammad Fardin Gholami; Daniel Lauster, Kai Ludwig, Julian Storm, Benjamin Ziem, Nikolai Severin, Christoph Böttcher, Jürgen P. Rabe, Andreas Herrmann, Mohsen Adeli, Rainer Haag
      Abstract: Polysulfated nanomaterials that mimic the extracellular cell matrix are of great interest for their potential to modulate cellular responses and to bind and neutralize pathogens. However, control over the density of active functional groups on such biomimetics is essential for efficient interactions, and this remains a challenge. In this regard, producing polysulfated graphene derivatives with control over their functionality is an intriguing accomplishment in order to obtain highly effective 2D platforms for pathogen interactions. Here, a facile and efficient method for the controlled attachment of a heparin sulfate mimic on the surface of graphene is reported. Dichlorotriazine groups are conjugated to the surface of graphene by a one-pot [2+1] nitrene cycloaddition reaction at ambient conditions, providing derivatives with defined functionality. Consecutive step by step conjugation of hyperbranched polyglycerol to the dichlorotriazine groups and eventual conversion to the polyglycerol sulfate result in the graphene based heparin biomimetics. Scanning force microscopy, cryo-transmission electron microscopy, and in vitro bioassays reveal strong interactions between the functionalized graphene (thoroughly covered by a sulfated polymer) and vesicular stomatitis virus. Infection experiments with highly sulfated versions of graphene drastically promote the infection process, leading to higher viral titers compared to nonsulfated analogues.This study demonstrates polysulfated graphene sheets mimicking the extracellular matrix of cells and their interactions with vesicular stomatitis virus (VSV). A New and facile method of controlling the density of functionalized graphene sheets is used and the multivalent interaction with the VSV virus has been successfully tuned.
      PubDate: 2017-03-08T05:20:36.605196-05:
      DOI: 10.1002/adfm.201606477
  • Next-Generation Activated Carbon Supercapacitors: A Simple Step in
           Electrode Processing Leads to Remarkable Gains in Energy Density
    • Authors: Jee Y. Hwang; Mengping Li, Maher F. El-Kady, Richard B. Kaner
      Abstract: The global supercapacitor market has been growing rapidly during the past decade. Today, virtually all commercial devices use activated carbon. In this work, it is shown that laser treatment of activated carbon electrodes results in the formation of microchannels that can connect the internal pores of activated carbon with the surrounding electrolyte. These microchannels serve as electrolyte reservoirs that in turn shorten the ion diffusion distance and enable better interaction between the electrode surfaces and electrolyte ions. The capacitance can be further increased through fast and reversible redox reactions on the electrode surface using a redox-active electrolyte, enabling the operation of a symmetric device at 2.0 V, much higher than the thermodynamic decompostion voltage of water. This simple approach can alleviate the low energy density of supercapacitors which has limited the widespread use of this technology. This work represents a clear advancement in the processing of activated carbon electrodes toward the next-generation of low-cost supercapacitors.Laser treatment of activated carbon electrodes results in micro-channels that connect internal pores of activated carbon with the surrounding electrolyte. These micro-channels serve as electrolyte reservoirs shortening the ion diffusion distance and enabling better interaction between electrode surfaces and electrolyte ions. The capacitance can be further increased through fast and reversible redox reactions using a redox active electrolyte.
      PubDate: 2017-03-07T08:15:56.623047-05:
      DOI: 10.1002/adfm.201605745
  • Amorphous Cobalt–Iron Hydroxide Nanosheet Electrocatalyst for Efficient
           Electrochemical and Photo-Electrochemical Oxygen Evolution
    • Authors: Wei Liu; Hu Liu, Lianna Dang, Hongxiu Zhang, Xiaolin Wu, Bin Yang, Zhongjian Li, Xingwang Zhang, Lecheng Lei, Song Jin
      Abstract: Finding efficient electrocatalysts for oxygen evolution reaction (OER) that can be effectively integrated with semiconductors is significantly challenging for solar-driven photo-electrochemical (PEC) water splitting. Herein, amorphous cobalt–iron hydroxide (CoFeH) nanosheets are synthesized by facile electrodeposition as an efficient catalyst for both electrochemical and PEC water oxidation. As a result of the high electrochemically active surface area and the amorphous nature, the optimized amorphous CoFeH nanosheets exhibit superior OER catalytic activity in alkaline environment with a small overpotential (280 mV) to achieve significant oxygen evolution (j = 10 mA cm−2) and a low Tafel slope (28 mV dec−1). Furthermore, CoFeH nanosheets are simply integrated with BiVO4 semiconductor to construct CoFeH/BiVO4 photoanodes that exhibit a significantly enhanced photocurrent density of 2.48 mA cm−2 (at 1.23 V vs reversible hydrogen electrode (RHE)) and a much lower onset potential of 0.23 V (vs RHE) for PEC-OER. Careful electrochemical and optical studies reveal that the improved OER kinetics and high-quality interface at the CoFeH/BiVO4 junction, as well as the excellent optical transparency of CoFeH nanosheets, contribute to the high PEC performance. This study establishes amorphous CoFeH nanosheets as a highly competitive candidate for electrochemical and PEC water oxidation and provides general guidelines for designing efficient PEC systems.Amorphous cobalt–iron hydroxide (CoFeH) nanosheets and BiVO4 are effectively integrated, constructing a catalyst/BiVO4 structure for achieving efficient photo-electrochemical (PEC) water oxidation. Benefiting from the properties of CoFeH and the rational design of electrocatalyst/semiconductor architecture, CoFeH/BiVO4 photoanodes exhibit an enhanced photocurrent density and a low onset potential for PEC water oxidation.
      PubDate: 2017-03-07T08:15:42.017723-05:
      DOI: 10.1002/adfm.201603904
  • High-Performance Colorful Semitransparent Polymer Solar Cells with
           Ultrathin Hybrid-Metal Electrodes and Fine-Tuned Dielectric Mirrors
    • Authors: Guiying Xu; Liang Shen, Chaohua Cui, Shanpeng Wen, Rongming Xue, Weijie Chen, Haiyang Chen, Jingwen Zhang, Hongkun Li, Yaowen Li, Yongfang Li
      Abstract: Polymer solar cells (PSCs) possess the unique features of semitransparency and coloration, which make them potential candidates for applications in aesthetic windows. Here, the authors fabricate inverted semitransparent PSCs with high-quality hybrid Au/Ag transparent top electrodes and fine-tuned dielectric mirrors (DMs). It is demonstrated that the device color can be tailored and the light harvesting in the PSCs can be enhanced by matching the bandgap of the polymer donors in the active layer with the specifically designed maximum-reflection-center-wavelengths of the DMs. A detailed chromaticity analysis of the semitransparent PSCs from both bottom and top (mirror) views is also carried out. Furthermore, the inverted semitransparent PSCs based on PTB7-Th:PC71BM with six pairs of DMs demonstrate a maximum power conversion efficiency (PCE) of 7.0% with an average visible transmittance (AVT) of 12.2%. This efficiency is one of the highest reported for semitransparent PSCs, corresponding to 81.4% of the PCE from opaque counterpart devices. The device design and processing method are also successfully adapted to a flexible substrate, resulting in a device with a competitive PCE of 6.4% with an AVT of 11.5%. To the best of our knowledge, this PCE value is the highest value reported for a flexible semitransparent PSC.This study demonstrates that the performance, reproducibility, and colors of inverted semitransparent polymer solar cells (PSCs) can be significantly improved or tuned by combining hybrid Au/Ag, fine-tuned dielectric mirrors, and active layers with various bandgaps. The PTB7-Th:PC71BM-based inverted semitransparent PSCs exhibit a maximum power conversion efficiency of 7.0% on rigid substrate and 6.4% on flexible substrate.
      PubDate: 2017-03-07T08:12:07.451042-05:
      DOI: 10.1002/adfm.201605908
  • A Nanoselenium Sponge for Instantaneous Mercury Removal to Undetectable
    • Authors: Snober Ahmed; John Brockgreitens, Ke Xu, Abdennour Abbas
      Abstract: Selective removal of aqueous mercury to levels below 10 ng L−1 or part per trillion remains an elusive goal for public health and environmental agencies. Here, it is shown that a low-cost nanocomposite sponge prepared by growing selenium (Se) nanomaterials on the surface and throughout the bulk of a polyurethane sponge exhibits a record breaking-mercury ion (Hg2+) removal rate, regardless of the pH. The exposure of aqueous solutions containing 10 mg L−1–12 ng L−1 Hg2+ to the sponge for a few seconds results in clean water with undetectable mercury levels (detection limit: 0.2 ng L−1). Such performance is far below the acceptable limits in drinking water (2 µg L−1), industrial effluents (0.2 µg L−1), and the most stringent surface water quality standards (1.3 ng L−1). The sponge shows a unique preference for Hg, does not retain water nutrients, and can significantly reduce the concentration of other heavy metal pollutants. Furthermore, the sponge shows no cytotoxic effect on human cells while exhibiting strong antimicrobial properties. The high affinity of Hg for Se results in irreversible sequestration and detoxification of mercury by the sponge, confirming the suitability for landfill disposal.A new polyurethane-selenium nanocomposite sponge is capable of removing aqueous mercury to undetectable levels within a few seconds. The sponge is not cytotoxic, does not retain water nutrients, reduces the concentration of other heavy metals, and exhibits antimicrobial properties that prevent biofouling. The used sponge meets the regulatory requirements for nonhazardous waste disposal.
      PubDate: 2017-03-06T07:40:41.97509-05:0
      DOI: 10.1002/adfm.201606572
  • A Waterborne Coating System for Preparing Robust, Self-healing,
           Superamphiphobic Surfaces
    • Authors: Hua Zhou; Hongxia Wang, Haitao Niu, Yan Zhao, Zhiguang Xu, Tong Lin
      Abstract: Existing coating systems for preparing superamphiphobic surfaces are predominantly confined to small-scale uses due to the heavy use of organic solvents. Waterborne coating treatment is highly desirable for the high safety, low cost, and nonenvironmental impact, but it remains difficult to develop due to the problems in forming durable, homogeneous coating from an aqueous dispersion of amphiphobic substances. In this study, the authors have proved that lyophobic nanoparticles, fluorinated alkyl silane (FAS), and fluorocarbon surfactant can form a stable dispersion in water, suitable for preparing durable superamphiphobic surfaces on various solid substrates. A series of substrates including fabrics, sponge, wood, glass, and metal, after being coated with this ternary coating system, shows superamphiphobicity with low contact angle hysteresis. The coating is durable enough against physical abrasion, repeated washing, boiling in water, and strong acid/base attacks. Benefiting from FAS, the coating also has a self-healing ability against both physical and chemical damages. The unexpected stability of the ternary dispersion is a result of the synergistic interaction of the three ingredients. Results from this study may promote the wide development of safe and cost-efficient superamphiphobic techniques for diverse applications.A waterborne coating system consisting of lyophobic nanoparticles, fluorinated alkyl silane, and fluorocarbon surfactant is developed to make various substrates having a superamphiphobic surface with low contact angle hysteresis. The coating is durable against physical abrasion, repeated washing, boiling in water, and strong acid/base attacks. It also has a self-healing ability against both physical and chemical damages.
      PubDate: 2017-03-06T07:35:38.268275-05:
      DOI: 10.1002/adfm.201604261
  • 3D Tunable, Multiscale, and Multistable Vibrational Micro-Platforms
           Assembled by Compressive Buckling
    • Authors: Xin Ning; Heling Wang, Xinge Yu, Julio A. N. T. Soares, Zheng Yan, Kewang Nan, Gabriel Velarde, Yeguang Xue, Rujie Sun, Qiyi Dong, Haiwen Luan, Chan Mi Lee, Aditya Chempakasseril, Mengdi Han, Yiqi Wang, Luming Li, Yonggang Huang, Yihui Zhang, John A. Rogers
      Abstract: Microelectromechanical systems remain an area of significant interest in fundamental and applied research due to their wide ranging applications. Most device designs, however, are largely 2D and constrained to only a few simple geometries. Achieving tunable resonant frequencies or broad operational bandwidths requires complex components and/or fabrication processes. The work presented here reports unusual classes of 3D micromechanical systems in the form of vibratory platforms assembled by controlled compressive buckling. Such 3D structures can be fabricated across a broad range of length scales and from various materials, including soft polymers, monocrystalline silicon, and their composites, resulting in a wide scope of achievable resonant frequencies and mechanical behaviors. Platforms designed with multistable mechanical responses and vibrationally decoupled constituent elements offer improved bandwidth and frequency tunability. Furthermore, the resonant frequencies can be controlled through deformations of an underlying elastomeric substrate. Systematic experimental and computational studies include structures with diverse geometries, ranging from tables, cages, rings, ring-crosses, ring-disks, two-floor ribbons, flowers, umbrellas, triple-cantilever platforms, and asymmetric circular helices, to multilayer constructions. These ideas form the foundations for engineering designs that complement those supported by conventional, micro-electromechanical systems, with capabilities that could be useful in systems for biosensing, energy harvesting, and others.The dynamical behavior of 3D structures assembled by compressive buckling from advanced materials is presented. The results include a broad set of 3D geometries with unique mechanical features, such as tunable resonant frequencies and multistable states. The results provide important design options for micro-electromechanical systems, resonators and kinetic energy harvesters.
      PubDate: 2017-03-03T14:00:30.000037-05:
      DOI: 10.1002/adfm.201605914
  • Terahertz Phonon Mode Engineering of Highly Efficient Organic Terahertz
    • Authors: Seung-Heon Lee; Bong Joo Kang, Ba-Wool Yoo, Seung-Chul Lee, Seung-Jun Lee, Mojca Jazbinsek, Hoseop Yun, Fabian Rotermund, O-Pil Kwon
      Abstract: For terahertz (THz) wave generators based on organic electrooptic crystals, their intrinsic phonon modes are playing an essential role in THz generation characteristics. Here, this study proposes an effective design strategy for THz phonon mode engineering of organic electrooptic salt crystals for efficient optical-to-THz frequency conversion. To reduce phonon-mode intensity, strongly electronegative trifluoromethyl group acting as strong hydrogen-bond acceptor is incorporated into molecular anions. New 2-(4-hydroxy-3-methoxystyryl)-1-methylquinolinium 4-(trifluoromethyl)benzenesulfonate (HMQ-4TFS) crystals exhibit a relatively small absorption coefficient in the THz spectral range between 0.5 and 4 THz, which is attributed to suppressed molecular vibrations due to strong hydrogen bonds involving the 4TFS anion. In addition, HMQ-4TFS crystals possess a very large macroscopic optical nonlinearity, comparable (or even higher) to benchmark stilbazolium crystals. Based on the low-intensity THz phonon modes and the large optical nonlinearity, a 0.37 mm thick HMQ-4TFS crystal pumped with 150 fs infrared laser pulses facilitates very efficient THz wave generation by optical rectification, delivering 23 times higher peak-to-peak THz electric field than the widely used standard inorganic ZnTe crystal (1.0 mm thick) and a broader spectral bandwidth. Therefore, strongly electronegative groups introduced into molecular salt electrooptic crystals provide a very promising design strategy of THz phonon mode engineering for developing intense broadband THz sources.New organic electrooptic quinolinium salt crystals exhibit high optical-to-THz conversion efficiency due to large optical nonlinearity and lower THz absorption, achieved by suppressing the THz vibrational modes by introduction of strongly electronegative groups acting as strong hydrogen-bond acceptor sites into molecular anions.
      PubDate: 2017-03-03T07:50:39.486558-05:
      DOI: 10.1002/adfm.201605583
  • Acoustic Separation of Nanoparticles in Continuous Flow
    • Authors: Mengxi Wu; Zhangming Mao, Kejie Chen, Hunter Bachman, Yuchao Chen, Joseph Rufo, Liqiang Ren, Peng Li, Lin Wang, Tony Jun Huang
      Abstract: The separation of nanoscale particles based on their differences in size is an essential technique to the nanoscience and nanotechnology community. Here, nanoparticles are successfully separated in a continuous flow by using tilted-angle standing surface acoustic waves. The acoustic field deflects nanoparticles based on volume, and the fractionation of nanoparticles is optimized by tuning the cutoff parameters. The continuous separation of nanoparticlesis demonstrated with a ≈90% recovery rate. The acoustic nanoparticle separation method is versatile, non-invasive, and simple.The standing acoustic wave field separates nanoparticles based on size differences. Larger particles are deflected further and filter out from the original route. This method enables size-based, label-free, and noncontact separation of varied types of nanoparticles.
      PubDate: 2017-03-03T07:46:02.92083-05:0
      DOI: 10.1002/adfm.201606039
  • Metal-Organic Framework Nanoparticles in Photodynamic Therapy: Current
           Status and Perspectives
    • Authors: Marjorie Lismont; Laurent Dreesen, Stefan Wuttke
      Abstract: This feature article covers the recent applications of metal-organic framework nanoparticles (MOF NPs) in photodynamic therapy (PDT) of cancer. It aims at giving the reader an overview about these two current research fields, i.e., MOF and PDT, and at highlighting the potential synergistic effect that could result from their association. After describing the general photophysics and photochemistry that underlie PDT, the relationship between photosensitizer (PS) properties and PDT requirements is discussed throughout the PSs historical development. This development reveals the advantages of using nanotechnology platforms for the creation of the ideal PS and leads us to define the fourth generation of PSs, which includes NPs built from the PS itself as porphysomes or PS-based MOF NPs. Especially, the precise spatial control over the PS assembly into well-defined MOF NPs, which keeps the PS in its monomeric form and prevents PS self-quenching, appears as a notable feature to solve PS solubility and aggregation issues and therefore improves the PDT efficiency. Finally, we discuss the future perspectives of MOF NPs in PDT and shed light on how promising these nanomaterials are.A new generation of photosensitizers, which includes metal-organic framework nanoparticles built from the photosensitizer itself as organic building unit, is described. The precise spatial control over the photosensitizer assembly into well-defined metal-organic framework scaffolds resolve the current solubility and aggregation issues and should therefore potentiate the outcome of nanoparticles-based cancer photodynamic therapy and allow for opening new perspectives in the field.
      PubDate: 2017-03-03T07:45:45.617228-05:
      DOI: 10.1002/adfm.201606314
  • Low-Temperature-Processed Printed Metal Oxide Transistors Based on Pure
           Aqueous Inks
    • Authors: William J. Scheideler; Rajan Kumar, Andre R. Zeumault, Vivek Subramanian
      Abstract: Additive patterning of transparent conducting metal oxides at low temperatures is a critical step in realizing low-cost transparent electronics for display technology and photovoltaics. In this work, inkjet-printed metal oxide transistors based on pure aqueous chemistries are presented. These inks readily convert to functional thin films at lower processing temperatures (T ≤ 250 °C) relative to organic solvent-based oxide inks, facilitating the fabrication of high-performance transistors with both inkjet-printed transparent electrodes of aluminum-doped cadmium oxide (ACO) and semiconductor (InOx). The intrinsic fluid properties of these water-based solutions enable the printing of fine features with coffee-ring free line profiles and smoother line edges than those formed from organic solvent-based inks. The influence of low-temperature annealing on the optical, electrical, and crystallographic properties of the ACO electrodes is investigated, as well as the role of aluminum doping in improving these properties. Finally, the all-aqueous-printed thin film transistors (TFTs) with inkjet-patterned semiconductor (InOx) and source/drain (ACO) layers are characterized, which show ideal low contact resistance (Rc < 160 Ω cm) and competitive transistor performance (µlin up to 19 cm2 V−1 s−1, Subthreshold Slope (SS) ≤150 mV dec−1) with only low-temperature processing (T ≤ 250 °C).High-mobility inkjet-printed transistors with transparent electrodes are fabricated at below 250 °C exclusively via aqueous ink chemistries. Intrinsic aqueous fluid properties lead to enhanced printing fidelity, high electrical performance, and better ambient stability relative to organic inks. Degenerately doped transparent conductors (CdO:Al) are developed as a low resistance inkjet-printed contact to an aqueous-printed InOx semiconductor.
      PubDate: 2017-03-03T07:45:31.202669-05:
      DOI: 10.1002/adfm.201606062
  • Redox Sensitive Hyaluronic Acid-Decorated Graphene Oxide for
           Photothermally Controlled Tumor-Cytoplasm-Selective Rapid Drug Delivery
    • Authors: Tingjie Yin; Jiyong Liu, Zekai Zhao, Yuanyuan Zhao, Lihui Dong, Meng Yang, Jianping Zhou, Meirong Huo
      Abstract: Nanocarriers capable of circumventing various biological barriers between the site of administration and the therapeutic target hold great potential for cancer treatment. Herein, a redox-sensitive, hyaluronic acid-decorated graphene oxide nanosheet (HSG) is developed for tumor cytoplasm-specific rapid delivery using near-infrared (NIR) irradiation controlled endo/lysosome disruption and redox-triggered cytoplasmic drug release. Hyaluronic acid (HA) modification through redox-sensitive linkages permits HSG a range of advantages over the standard graphene oxide, including high biological stability, enhanced drug-loading capacity for aromatic molecules, HA receptor-mediated active tumor targeting, greater NIR absorption and thermal energy translation, and a sharp redox-dependent response for accelerated cargo release. Results of in vivo and in vitro testing indicate a high loading of doxorubicin (DOX) onto HSG. Selective delivery to HA-receptor overexpressing tumors is achieved through passive and active targeting with minimized unfavorable interactions with blood components. Cytoplasm-specific DOX delivery is then achieved through NIR controlled endo/lysosome disruption along with redox-triggered release of DOX in glutathione rich areas. HSG's specificity is resulted in enhanced cytotoxicity of chemotherapeutics with minimal collateral damage to healthy tissues in a xenograft animal tumor model. HSG is validated the programmed delivery of therapeutic agents in a spatiotemporally controlled manner to overcome multiple biological barriers results in specific and enhanced cancer treatment.A redox-sensitive, hyaluronic acid-decorated graphene oxide nanosheet is constructed for tumor cytoplasm-specific rapid delivery using near-infrared irradiation controlled endo/lysosome disruption and redox-triggered cytoplasmic drug release. This programmed delivery system is demonstrated to overcome multiple biological barriers in a spatiotemporally controlled manner for a specific and enhanced cancer treatment.
      PubDate: 2017-03-03T07:40:41.795163-05:
      DOI: 10.1002/adfm.201604620
  • Determination of Crystal Axes in Semimetallic T′-MoTe2 by Polarized
           Raman Spectroscopy
    • Authors: Junyong Wang; Xin Luo, Shisheng Li, Ivan Verzhbitskiy, Weijie Zhao, Shunfeng Wang, Su Ying Quek, Goki Eda
      Abstract: Distorted octahedral T′ phase of MoTe2 has recently attracted significant interest due to its predicted topological states and novel charge transport properties. Here, we report a nondestructive method for determining the crystal orientation of few-layer T′-MoTe2 flakes by polarized Raman spectroscopy. The experimentally observed Raman modes are assigned to eigenmodes of vibrations predicted by density functional theory calculations. Polarized Raman measurements reveal four distinct types of angle-dependent intensity variations. From group theory, it can be deduced that the intensity of the Bg mode reaches a maximum in the x¯(yz)x configuration when the polarization vector of the incident light is either parallel or orthogonal to the metal–metal zigzag chain direction. The intensity variation of the Bg mode cannot be used to unambiguously determine the crystal orientation. Using electron diffraction analysis, it is demonstrated that the intensity of the Ag mode at around 162 cm−1 reaches a maximum when the polarization vector of the incident light is parallel to the metal–metal chain direction in the x¯(yy)x configuration. Furthermore, a simple method is proposed for identifying crystal orientation in nonpolarized Raman spectroscopy.In-plane anisotropy of thin-layer semimetallic T′-MoTe2 is investigated by angle-resolved Raman spectroscopy. Density functional theory calculations and group theory analysis reveal four types of distinct angular dependence for Ag and Bg modes. In conjunction with electron diffraction analysis, a simple method for determining the crystal orientation is developed.
      PubDate: 2017-03-02T04:30:42.489286-05:
      DOI: 10.1002/adfm.201604799
  • Fe2O3 Nanoneedles on Ultrafine Nickel Nanotube Arrays as Efficient Anode
           for High-Performance Asymmetric Supercapacitors
    • Authors: Yang Li; Jing Xu, Tao Feng, Qiaofeng Yao, Jianping Xie, Hui Xia
      Abstract: High performance of electrochemical energy storage devices depends on the smart structure engineering of electrodes, including the tailored nanoarchitectures of current collectors and subtle hybridization of active materials. To improve the anode supercapacitive performance of Fe2O3 for high-voltage asymmetric supercapacitors, here, a hybrid core-branch nanoarchitecture is proposed by integrating Fe2O3 nanoneedles on ultrafine Ni nanotube arrays (NiNTAs@Fe2O3 nanoneedles). The fabrication process employs a bottom-up strategy via a modified template-assisted method starting from ultrafine ZnO nanorod arrays, ensuring the formation of ultrafine Ni nanotube arrays with ultrathin tube walls. The novel developed NiNTAs@Fe2O3 nanoneedle electrode is demonstrated to be a highly capacitive anode (418.7 F g−1 at 10 mV s−1), matching well with the similarly built NiNTAs@MnO2 nanosheet cathode. Contributed by the efficient electron collection paths and short ion diffusion paths in the uniquely designed anode and cathode, the asymmetric supercapacitors exhibit an excellent maximum energy density of 34.1 Wh kg−1 at the power density of 3197.7 W kg−1 in aqueous electrolyte and 32.2 Wh kg−1 at the power density of 3199.5 W kg−1 in quasi-solid-state gel electrolyte.A core-branch nanoarchitecture, by integrating Fe2O3 nanoneedles on ultrafine Ni nanotube arrays, is developed as advanced anode for supercapacitors. The smart electrode design realizes large surface area with fast charge transport. By adopting the similar nanoarchitecture design for both Fe2O3 anode and MnO2 cathode, 1.6 V aqueous and solid-state asymmetric supercapacitors with high energy and power densities have been demonstrated.
      PubDate: 2017-03-01T07:21:14.07687-05:0
      DOI: 10.1002/adfm.201606728
  • Zn-MOF-74 Derived N-Doped Mesoporous Carbon as pH-Universal
           Electrocatalyst for Oxygen Reduction Reaction
    • Authors: Lin Ye; Guoliang Chai, Zhenhai Wen
      Abstract: It is of increasing importance to explore new low-cost and high-activity electrocatalysts for oxygen reduction reaction (ORR), which have had a substantial impact across a diverse range of energy conversion system, including various fuel cell and metal–air batteries. Although engineering carbon nanostructures have been widely explored as a candidate class of Pt-based ORR electrocatalysts owing to their proved high activity, outstanding stability, and ease of use, there still remains a daunting challenge to develop high activity metal-free electrocatalysts in pH-universal electrolyte system. Here, a reliable and controllable route amenable to prepare nitrogen-doped porous carbon (NPC) with high yields and exceptional quality is described. The as-prepared NPC shows advantages of high activity, high durability, and methanol-tolerant as an efficient pH-universal electrocatalyst for ORR, showing comparable or even better activity as compared with the commercial Pt/C catalysts not only in alkaline media but also in acidic and neutral electrolyte. Systematic electrochemical studies, combining with density functional theory calculation, demonstrate the unique nitrogen-doping species and favorable pores in the as-designed NPC synergistically contribute to the significantly improved catalytic activity in pH-universal medium. The present work potentially presents an important breakthrough in developing ORR electrocatalysts for various fuel cells.With oxygen-rich Zn-metal–organic framework-74 as precursor, nitrogen-doped porous carbon (NPC) with pore size of ≈10–12 nm is developed as an ef ficient electrocatalyst for oxygen reduction reaction (ORR), the optimized NPC sample shows comparable or even superior ORR activity compared with the commercial Pt/C catalysts not only in alkaline media but also in acidic and neutral electrolyte.
      PubDate: 2017-03-01T07:20:47.670587-05:
      DOI: 10.1002/adfm.201606190
  • Systematic Study of Oxygen Vacancy Tunable Transport Properties of
           Few-Layer MoO3−x Enabled by Vapor-Based Synthesis
    • Authors: Eve D. Hanson; Luc Lajaunie, Shiqiang Hao, Benjamin D. Myers, Fengyuan Shi, Akshay A. Murthy, Chris Wolverton, Raul Arenal, Vinayak P. Dravid
      Abstract: Bulk and nanoscale molybdenum trioxide (MoO3) has shown impressive technologically relevant properties, but deeper investigation into 2D MoO3 has been prevented by the lack of reliable vapor-based synthesis and doping techniques. Herein, the successful synthesis of high-quality, few-layer MoO3 down to bilayer thickness via physical vapor deposition is reported. The electronic structure of MoO3 can be strongly modified by introducing oxygen substoichiometry (MoO3−x), which introduces gap states and increases conductivity. A dose-controlled electron irradiation technique to introduce oxygen vacancies into the few-layer MoO3 structure is presented, thereby adding n-type doping. By combining in situ transport with core-loss and monochromated low-loss scanning transmission electron microscopy–electron energy-loss spectroscopy studies, a detailed structure–property relationship is developed between Mo-oxidation state and resistance. Transport properties are reported for MoO3−x down to three layers thick, the most 2D-like MoO3−x transport hitherto reported. Combining these results with density functional theory calculations, a radiolysis-based mechanism for the irradiation-induced oxygen vacancy introduction is developed, including insights into favorable configurations of oxygen defects. These systematic studies represent an important step forward in bringing few-layer MoO3 and MoO3−x into the 2D family, as well as highlight the promise of MoO3−x as a functional, tunable electronic material.A physical vapor deposition synthesis of few-layer MoO3 is reported, along with an electron-beam technique to introduce oxygen vacancies into the structure, forming few-layer MoO3−x. Combining in situ transport and scanning transmission electron microscopy studies, a robust and systematic structure–property relationship between the few-layer Mo-oxidation state and resistance is provided.
      PubDate: 2017-03-01T07:16:07.177214-05:
      DOI: 10.1002/adfm.201605380
  • Long-Term Structural Evolution of an Intercalated Layered Semiconductor
    • Authors: Annabel R. Chew; Jose J. Fonseca, Oscar D. Dubon, Alberto Salleo
      Abstract: Intercalated molecules can dramatically modify the electronic band structure of layered semiconductors, significantly altering the optical properties of the material. In the layered monochalcogenide Gallium Telluride (GaTe), exposure to air induces a nearly 1 eV reduction of its band gap due to the interlayer diffusion and chemisorption of oxygen. The effect of oxygen chemisorption at the Te-terminated surfaces on the structure of GaTe, however, is much less known. To better understand the structure–property relationship of intercalated GaTe, a systematic, long-term, X-ray diffraction study has been performed on GaTe exfoliated crystals exposed to ambient conditions. It is observed that the structural changes are not limited to a previously observed short-term increase in lattice expansion. Over the course of months and even years after exfoliation, the oxygen adsorbates continue to modify the structure of GaTe, inducing significant disorder and grain reorientation. It is estimated that approximately one out of every two grains is slightly displaced by the intercalating oxygen, demonstrating a significant increase in grain mosaicity, while still maintaining the original {−2 0 1} out-of-plane texture. Correlating these structural transformations to observed changes in electrical and optical properties will enable capitalization of the use of adsorbates to engineer novel properties in these layered materials.Significant structural changes are observed in layered GaTe due to the chemisorption of oxygen to the Te atoms, which have been shown to effect changes in the material's band structure. Under ambient conditions, oxygen intercalation leads to an initial nonuniform lattice expansion, as well as long-term reorientation of subgrains present in the GaTe flakes.
      PubDate: 2017-03-01T07:15:37.865802-05:
      DOI: 10.1002/adfm.201605038
  • Fast, Scalable Synthesis of Micronized Ge3N4@C with a High Tap Density for
           Excellent Lithium Storage
    • Authors: Chanhoon Kim; Gaeun Hwang, Ji-Won Jung, Su-Ho Cho, Jun Young Cheong, Sunghee Shin, Soojin Park, Il-Doo Kim
      Abstract: Nanostructuring has significantly contributed to alleviating the huge volume expansion problem of the Ge anodes. However, the practical use of nanostructured Ge anodes has been hindered due to several problems including a low tap density, poor scalability, and severe side reactions. Therefore, micrometer-sized Ge is desirable for practical use of Ge-based anode materials. Here, micronized Ge3N4 with a high tap density of 1.1 mg cm−2 has been successfully developed via a scalable wet oxidation and a subsequent nitridation process of commercially available micrometer-sized Ge as the starting material. The micronized Ge3N4 shows much-suppressed volume expansion compared to micrometer-sized Ge. After the carbon coating process, a thin carbon layer (≈3 nm) is uniformly coated on the micronized Ge3N4, which significantly improves electrical conductivity. As a result, micronized Ge3N4@C shows high reversible capacity of 924 mAh g−1 (2.1 mAh cm−2) with high mass loading of 3.5 mg cm−2 and retains 91% of initial capacity after 300 cycles at a rate of 0.5 C. Additionally, the effectiveness of Ge3N4@C as practical anodes is comprehensively demonstrated for the full cell, showing stable cycle retention and especially excellent rate capability, retaining 47% of its initial capacity at 0.2 C for 12 min discharge/charge condition.The micronized Ge3N4@C with a high tap density is prepared as an excellent lithium storage material. Due to the limited conversion reaction of Ge3N4 and Li+, Ge3N4@C shows significantly reduced volume expansion at fully lithiated state with the high areal capacity of 2.1 mAh cm−2 and excellent reversible capacity even after 300 cycles.
      PubDate: 2017-02-28T12:40:45.257975-05:
      DOI: 10.1002/adfm.201605975
  • Textile Resistance Switching Memory for Fabric Electronics
    • Authors: Anjae Jo; Youngdae Seo, Museok Ko, Chaewon Kim, Heejoo Kim, Seungjin Nam, Hyunjoo Choi, Cheol Seong Hwang, Mi Jung Lee
      Abstract: A new type of wearable electronic device, called a textile memory, is reported. This is created by combining the unique properties of Al-coated threads with a native layer of Al2O3 as a resistance switching layer, and carbon fiber as the counter-electrode, which induces a fluent redox reaction at the interface under a small electrical bias (typically 2–3 V). These two materials can be embroidered into an existing cloth or woven into a novel cloth. The electrical resistance of the contacts is repeatedly switched by the bias polarity, as observed in the recently highlighted resistance switching memory. The devices with different structure from the solid metal-insulator-metal devices show reliable resistance switching behaviors in textile form by single stitch and in array as well that would render this new type of material system applicable to a broad range of emerging wearable devices. Such behavior cannot be achieved in other material choices, revealing the uniqueness of this material system.Textile resistive switching memory devices are fabricated using common threads with aluminum coating and carbon fibers by simple physical contact by weaving without additional resistance switching layer. A redox reaction between native aluminum oxide and carbon creates a conducting path upon bias applied.
      PubDate: 2017-02-28T12:40:32.677476-05:
      DOI: 10.1002/adfm.201605593
  • Fluorescent Nanomaterials for the Development of Latent Fingerprints in
           Forensic Sciences
    • Authors: Meng Wang; Ming Li, Aoyang Yu, Ye Zhu, Mingying Yang, Chuanbin Mao
      Abstract: This review presents an overview on the application of latent fingerprint development techniques in forensic sciences. At present, traditional developing methods such as powder dusting, cyanoacrylate fuming, chemical method, and small particle reagent method, have all been gradually compromised given their emerging drawbacks such as low contrast, sensitivity, and selectivity, as well as high toxicity. Recently, much attention has been paid to the use of fluorescent nanomaterials including quantum dots (QDs) and rare earth upconversion fluorescent nanomaterials (UCNMs) due to their unique optical and chemical properties. Thus, this review lays emphasis on latent fingerprint development based on QDs and UCNMs. Compared to latent fingerprint development by traditional methods, the new methods using fluorescent nanomaterials can achieve high contrast, sensitivity, and selectivity while showing reduced toxicity. Overall, this review provides a systematic overview on such methods.This review presents an overview on the application of latent fingerprint development techniques in forensic sciences, especially on the good performance of fluorescent nanomaterials including quantum dots and rare earth upconversion nanomaterials in latent fingerprint development.
      PubDate: 2017-02-28T02:36:38.339186-05:
      DOI: 10.1002/adfm.201606243
  • One-Step Hierarchical Assembly of Spheres-in-Lamellae Nanostructures from
           Solvent-Annealed Thin Films of Binary Diblock Copolymer Micelles
    • Authors: Se Hee Kim; Kookheon Char, Seong Il Yoo, Byeong-Hyeok Sohn
      Abstract: Hierarchical assemblies of dissimilar block copolymers (BCPs) can reveal interesting perspectives on material properties and device performance by providing multiple functionalities. Up to now, hierarchical assemblies of BCPs have been mostly prepared by stepwise assembling methods, in which the first type of BCP nanodomains is used as predefined patterns to guide the second-level assembly of another BCP. On the other hand, single-step blending methods suffer from a dilemma in the creation of hierarchical patterns because blending dissimilar BCPs typically induces either macrophase separation of component BCPs or chain-level hybridization into a single morphology. The present study is designed to overcome this apparent dilemma in polymer blends by exploiting a solvent annealing method. In particular, hierarchically assembled spheres-in-lamellae structures from a solvent-annealed blended film of binary polystyrene-block-poly(2-vinylpyrdine) and polystyrene-block-poly(4-vinyl pyridine) micelles are prepared. The focus of the current study is to understand the different effects of solvent vapor on the component BCPs and the molecular mechanism for the one-step assembling process. By addressing this issue, the parallelism in the phase behavior of BCP micelles and inorganic nanoparticles is highlighted, the underlying physical processes of which could be suggested as a one-step assembly principle for hierarchical superstructures beyond the previously reported multistep methods.Hierarchically assembled spheres-in-lamellae structures have been prepared from a solvent-annealed blended film of binary polystyrene-block-poly(2-vinylpyrdine) and polystyrene-block-poly(4-vinyl pyridine) micelles. In addressing the assembling mechanism, an interesting parallelism in the phase behavior of polymer micelles and inorganic nanoparticles is discovered, the underlying physical processes of which could be suggested as a one-step assembly principle for hierarchical superstructures.
      PubDate: 2017-02-27T08:55:32.046547-05:
      DOI: 10.1002/adfm.201606715
  • A New rGO-Overcoated Sb2Se3 Nanorods Anode for Na+ Battery: In Situ X-Ray
           Diffraction Study on a Live Sodiation/Desodiation Process
    • Authors: Xing Ou; Chenghao Yang, Xunhui Xiong, Fenghua Zheng, Qichang Pan, Chao Jin, Meilin Liu, Kevin Huang
      Abstract: Sodium ion batteries (SIBs) are a promising alternative to lithium ion batteries for a broader range of energy storage applications in the future. However, the development of high-performance anode materials is a bottleneck of SIBs advancement. In this work, Sb2Se3 nanorods uniformly wrapped by reduced graphene oxide (rGO) as a promising anode material for SIBs are reported. The results show that such Sb2Se3/rGO hybrid anode yields a high reversible mass-specific energy capacity of 682, 448, and 386 mAh g−1 at a rate of 0.1, 1.0, and 2.0 A g−1, respectively, and sustains at least 500 stable cycles at a rate of 1.0 A g−1 with an average mass-specific energy capacity of 417 mAh g−1 and capacity retention of 90.2%. In situ X-ray diffraction study on a live SIB cell reveals that the observed high performance is a result of the combined Na+ intercalation, conversion reaction between Na+ and Se, and alloying reaction between Na+ and Sb. The presence of rGO also plays a key role in achieving high rate capacity and cycle stability by providing good electrical conductivity, tolerant accommodation to volume change, and strong electron interactions to the base Sb2Se3 anode.A hierarchically structured Sb2Se3/reduced graphene oxide (rGO) hybrid, in which Sb2Se3 nanorods are evenly wrapped by rGO nanosheets, has been fabricated as anode material for sodium ion batteries. The reaction mechanism of Sb2Se3 has been investigated by in situ X-ray diffraction, confirming that its high performance is a result of combined Na+ intercalation, conversion, and alloying reaction.
      PubDate: 2017-02-24T09:06:00.886737-05:
      DOI: 10.1002/adfm.201606242
  • Ultra-Lightweight and Highly Adaptive All-Carbon Elastic Conductors with
           Stable Electrical Resistance
    • Authors: Han Wang; Weibang Lu, Jiangtao Di, Da Li, Xiaohua Zhang, Min Li, Zuoguang Zhang, Lianxi Zheng, Qingwen Li
      Abstract: The rapid development of wearable electronics needs flexible conductive materials that have stable electrical properties, good mechanical reliability, and broad environmental tolerance. Herein, ultralow-density all-carbon conductors that show excellent elasticity and high electrical stability when subjected to bending, stretching, and compression at high strains, which are superior to previously reported elastic conductors, are demonstrated. These all-carbon conductors are fabricated from carbon nanotube forms, with their nanotube joints being selectively welded by amorphous carbon. The joint-welded foams have a robust 3D nanotube network with fixed nodes and mobile nanotube segments, and thus have excellent electrical and mechanical stabilities. They can readily scale up, presenting a new type of nonmetal elastic conductor for many possible applications.Ultra-lightweight and highly adaptive all-carbon elastic conductors are achieved by the controllable welding of nanotube joints in carbon nanotube foams with amorphous carbon. These conductors show high conductivity and excellent electrical reliability even under severe bending, stretching, and solution soaking, presenting a new type of nonmetal elastic conductor for many potential applications.
      PubDate: 2017-02-22T08:50:41.041719-05:
      DOI: 10.1002/adfm.201606220
  • Highly Anisotropic Suspended Planar-Array Chips with Multidimensional
           Sub-Micrometric Biomolecular Patterns
    • Authors: Juan Pablo Agusil; Núria Torras, Marta Duch, Jaume Esteve, Lluïsa Pérez-García, Josep Samitier, José A. Plaza
      Abstract: Suspended planar-array (SPA) chips embody millions of individual miniaturized arrays to work in extremely small volumes. Here, the basis of a robust methodology for the fabrication of SPA silicon chips with on-demand physical and chemical anisotropies is demonstrated. Specifically, physical traits are defined during the fabrication process with special focus on the aspect ratio, branching, faceting, and size gradient of the final chips. Additionally, the chemical attributes augment the functionality of the chips with the inclusion of complete coverage or patterns of selected biomolecules on the surface of the chips with contact printing techniques, offering an extremely high versatility, not only with the choice of the pattern shape and distribution but also in the choice of biomolecular inks to pattern. This approach increases the miniaturization of printed arrays in 3D structures by two orders of magnitude compared to those previously demonstrated. Finally, functional micrometric and sub-micrometric patterned features are demonstrated with an antibody binding assay with the recognition of the printed spots with labeled antibodies from solution. The selective addition of physical and chemical attributes on the suspended chips represents the basis for future biomedical assays performed within extremely small volumes.Miniaturized silicon-based chips incorporating customized physical and chemical anisotropies for molecular sensing are demonstrated. The microfabrication approach using photolithography dictates their physical anisotropy, while subsequent 2D or 3D chemical modifications extend their functionality by incorporating homogeneous or patterned chemical signatures. The high versatility of the anisotropic chips opens a vast number of applications for future life science applications.
      PubDate: 2017-02-22T03:06:04.453522-05:
      DOI: 10.1002/adfm.201605912
  • Silver Zeolite Composites-Based LEDs: A Novel Solid-State Lighting
    • Authors: Koen Kennes; Eduardo Coutino-Gonzalez, Cristina Martin, Wouter Baekelant, Maarten B. J. Roeffaers, Mark Van der Auweraer
      Abstract: Silver clusters incorporated in a zeolite matrix represent a promising alternative for rare earth phosphors, organic dyes, and quantum dots as emitters in organic and hybrid organic/inorganic light-emitting diodes (OLEDs). Compared to other existing types of emitters, they combine an excellent stability to oxygen and humidity with a high luminescence quantum yield and color tunability. This study reports on the first use of these silver exchanged zeolites embedded in polyvinyl carbazole (PVK), which is expected to act as a conducting matrix, as emitters in a single-layer OLED. It is demonstrated that the introduction of these Ag zeolites leads to electroluminescence bands that clearly differ from pristine PVK OLEDs as well as from the photoluminescence spectra of the Ag zeolites. The current density and the spectral properties observed in these devices are strongly influenced by the zeolite silver loading, paving the way for a new type of easily tunable hybrid and cost-effective OLEDs.The development of innovative, efficient, and cost-effective lighting sources is nowadays of paramount importance. This study describes for the first time the assembly and characterization of silver-exchanged zeolite-based light-emitting diodes (LEDs). A basic, single-layer organic LED architecture is employed in which silver exchanged zeolites are incorporated. The electroluminescence colors are controlled by the silver concentration in the zeolites.
      PubDate: 2017-02-21T10:01:43.824781-05:
      DOI: 10.1002/adfm.201606411
  • Rapid Pseudocapacitive Sodium-Ion Response Induced by 2D Ultrathin Tin
           Monoxide Nanoarrays
    • Authors: Minghua Chen; Dongliang Chao, Jilei Liu, Jiaxu Yan, Bowei Zhang, Yizhong Huang, Jianyi Lin, Ze Xiang Shen
      Abstract: Nanostructured tin-based anodes are promising for both lithium and sodium ion batteries (LIBs and SIBs), but their performances are limited by the rate capability and long-term cycling stability. Here, ultrathin SnO nanoflakes arrays are in situ grown on highly conductive graphene foam/carbon nanotubes substrate, forming a unique, flexible, and binder-free 3D hybrid structure electrode. This electrode exhibits an excellent Na+ storage capacity of 580 mAh g−1 at 0.1 A g−1, and to the best of our knowledge, has the longest-reported high-rate cycling (1000 cycles at 1 A g−1) among tin-based SIB anodes. Compared with its LIB performance, the enhanced pseudocapacitive contribution in SIB is proved to be the origin of fast kinetics and long durability of the electrode. Moreover, Raman peaks from the full sodiation product Na15Sn4 at 75 and 105 cm−1 are successfully detected and also proved by density functional theory calculations, which could be a promising clue for structure evolution analysis of other tin-based electrodes.Flexible, binder-free electrode composed of 2D ultrathin (≈2.5 nm) SnO nanoflake arrays on graphene foam/carbon nanotubes foam is fabricated. Density functional theory calculation, quantitative capacitive analysis, and ex situ Raman and high-resolution transmission electron microscopy verify the role of pseudocapacitive contribution to high-rate Na+ storage and long-term cycle life of sodium ion battery.
      PubDate: 2017-02-20T09:40:36.849121-05:
      DOI: 10.1002/adfm.201606232
  • A Lyotropic Liquid-Crystal-Based Assembly Avenue toward Highly Oriented
           Vanadium Pentoxide/Graphene Films for Flexible Energy Storage
    • Authors: Haiqing Liu; Yanping Tang, Chi Wang, Zhixiao Xu, Chongqing Yang, Tao Huang, Fan Zhang, Dongqing Wu, Xinliang Feng
      Abstract: A novel lyotropic liquid-crystal (LC) based assembly strategy is developed for the first time, to fabricate composite films of vanadium pentoxide (V2O5) nanobelts and graphene oxide (GO) sheets, with highly oriented layered structures. It is found that similar lamellar LC phases can be simply established by V2O5 nanobelts alone or by a mixture of V2O5 nanobelts and GO nanosheets in their aqueous dispersions. More importantly, the LC phases can be retained with any proportion of V2O5 nanobelts and GO, which allows facile optimization of the ratio of each component in the resulting films. Named VrGO, composite films manifest high electrical conductivity, good mechanical stability, and excellent flexibility, which allow them to be utilized as high performance electrodes in flexible energy storage devices. As demonstrated in this work, the VrGO films containing 67 wt% V2O5 exhibit excellent capacitance of 166 F g−1 at 10 A g−1; superior to those of the previously reported composites of V2O5 and nanocarbon. Moreover, the VrGO film in flexible lithium ion batteries delivers a high capacity of 215 mAh g−1 at 0.1 A g−1; comparable to the best V2O5 based cathode materials.A novel lyotropic liquid-crystal-based assembly strategy is developed for the first time to fabricate composite films of vanadium pentoxide nanobelts and graphene oxide sheets with highly oriented layered structures. The resulting films manifest high electrical conductivity, good mechanical stability, and excellent flexibility, which allow them to be utilized as high performance electrodes in flexible energy storage devices.
      PubDate: 2017-02-15T07:15:40.198533-05:
      DOI: 10.1002/adfm.201606269
  • Ultrathin Nickel–Cobalt Phosphate 2D Nanosheets for Electrochemical
           Energy Storage under Aqueous/Solid-State Electrolyte
    • Authors: Bing Li; Peng Gu, Yongcheng Feng, Guangxun Zhang, Kesheng Huang, Huaiguo Xue, Huan Pang
      Abstract: 2D materials are ideal for constructing flexible electrochemical energy storage devices due to their great advantages of flexibility, thinness, and transparency. Here, a simple one-step hydrothermal process is proposed for the synthesis of nickel–cobalt phosphate 2D nanosheets, and the structural influence on the pseudocapacitive performance of the obtained nickel–cobalt phosphate is investigated via electrochemical measurement. It is found that the ultrathin nickel–cobalt phosphate 2D nanosheets with an Ni/Co ratio of 4:5 show the best electrochemical performance for energy storage, and the maximum specific capacitance up to 1132.5 F g−1. More importantly, an aqueous and solid-state flexible electrochemical energy storage device has been assembled. The aqueous device shows a high energy density of 32.5 Wh kg−1 at a power density of 0.6 kW kg−1, and the solid-state device shows a high energy density of 35.8 Wh kg−1 at a power density of 0.7 kW kg−1. These excellent performances confirm that the nickel–cobalt phosphate 2D nanosheets are promising materials for applications in electrochemical energy storage devices.Nickel–cobalt phosphate 2D ultrathin nanosheets are synthesized by a one-step hydrothermal process. Several reaction conditions are changed to explore the impact of the materials. The structural influence on the pseudocapacitive performance of the obtained sample is investigated via electrochemical measurement. It is found that the sample with an Ni/Co ratio of 4:5 shows the best electrochemical energy storage.
      PubDate: 2017-02-15T03:40:37.7745-05:00
      DOI: 10.1002/adfm.201605784
  • Nano/Microrobots Meet Electrochemistry
    • Authors: James Guo Sheng Moo; Carmen C. Mayorga-Martinez, Hong Wang, Bahareh Khezri, Wei Zhe Teo, Martin Pumera
      Abstract: Artificial autonomous self-propelled nano and microrobots are an important part of contemporary technology. They are typically self-powered, taking chemical energy from their environment and converting it to motion. They can move in complex environments and channels, deliver cargo, perform nanosurgery, act as chemotaxis and perform sense-and-act actions. The electrochemistry is closely interwoven within this field. In the case of self-electrophoretically driven nano/microrobots, electrochemical mechanism has been the basis of power, which translates chemical energy to motion. Electrochemistry is also a major tool for the fabrication of these micro and nanodevices. Electrochemistry and electric fields can be used for the directing of nanorobots and for detection of their positions. Ultimately, nano and microrobots can dramatically improve performances of electrochemical sensors and biosensors, as well as of the energy generating devices. Here, all aspects in the fundamentals and applications of electrochemistry in the realm of nano- and microrobots are reviewed.The nexus between electrochemistry and nano/microrobots is closely interwoven. In this confluence, fabrication, powering, control and applications of these self-propelled devices are illustrated. Understanding these fundamentals will push new frontiers for the locomotion of nano/microrobots.
      PubDate: 2017-02-13T07:20:42.12489-05:0
      DOI: 10.1002/adfm.201604759
  • Scaling the Aspect Ratio of Nanoscale Closely Packed Silicon Vias by
           MacEtch: Kinetics of Carrier Generation and Mass Transport
    • Authors: Jeong Dong Kim; Parsian K. Mohseni, Karthik Balasundaram, Srikanth Ranganathan, Jayavel Pachamuthu, James J. Coleman, Xiuling Li
      Abstract: Metal-assisted chemical etching (MacEtch) has shown tremendous success as an anisotropic wet etching method to produce ultrahigh aspect ratio semiconductor nanowire arrays, where a metal mesh pattern serves as the catalyst. However, producing vertical via arrays using MacEtch, which requires a pattern of discrete metal disks as the catalyst, has often been challenging because of the detouring of individual catalyst disks off the vertical path while descending, especially at submicron scales. Here, the realization of ordered, vertical, and high aspect ratio silicon via arrays by MacEtch is reported, with diameters scaled from 900 all the way down to sub-100 nm. Systematic variation of the diameter and pitch of the metal catalyst pattern and the etching solution composition allows the extraction of a physical model that, for the first time, clearly reveals the roles of the two fundamental kinetic mechanisms in MacEtch, carrier generation and mass transport. Ordered submicron diameter silicon via arrays with record aspect ratio are produced, which can directly impact the through-silicon-via technology, high density storage, photonic crystal membrane, and other related applications.Ordered, vertical, and high aspect ratio submicron silicon via array is fabricated by metal-assisted chemical etching. The physical model extracted from systematic variation of catalyst pattern and etching solution reveals the roles of two fundamental kinetic mechanisms, carrier generation and mass transport. This potentially disruptive etching technology can impact the formation of through-silicon-vias and high density electronic and photonic devices.
      PubDate: 2017-02-10T02:32:48.272636-05:
      DOI: 10.1002/adfm.201605614
  • Unveiling a Key Intermediate in Solvent Vapor Postannealing to Enlarge
           Crystalline Domains of Organometal Halide Perovskite Films
    • Authors: Shuang Xiao; Yang Bai, Xiangyue Meng, Teng Zhang, Haining Chen, Xiaoli Zheng, Chen Hu, Yongquan Qu, Shihe Yang
      Abstract: Hybrid organic/inorganic perovskite solar cells (PSCs) have shown great potential in meeting the future challenges in energy and environment. Solvent-vapor-assisted posttreatment strategies are developed to improve the perovskite film quality for achieving higher efficiency. However, the intrinsic working mechanisms of these strategies have not been well understood yet. This study identifies an MA2Pb3I8(DMSO)2 intermediate phase formed during the annealing process of methylammonium lead triiodide in dimethyl sulfoxide (DMSO) atmosphere and located the reaction sites at perovskite grain boundaries by observing and rationalizing the growth of nanorods of the intermediate. This enables us to propose and validate an intermediate-assisted grain-coarsening model, which highlights the activation energy reduction for grain boundary migration. Leveraging this mechanism, this study uses MABr/DMSO mixed vapor to further enhance grain boundary migration kinetics and successfully obtain even larger grains, leading to an impressive improvement in power conversion efficiency (17.64%) relative to the pristine PSCs (15.13%). The revelation of grain boundary migration-assisted grain growth provides a guide for the future development of polycrystalline perovskite thin-film solar cells.MA2Pb3I8(DMSO)2 intermediate is identified and tracked during the methylammonium lead triiodide thin-film anneal process under dimethyl sulfoxide (DMSO) solvent vapor, which helps to reduce the activation energy of perovskite grain boundary migration. Leveraging this mechanism, an MABr/DMSO mix vapor anneal method is developed to further facillitate grain goundary migration to achieve 17.64% efficiency in NiO-based inverted perovskite solar cell.
      PubDate: 2017-02-10T02:26:10.252501-05:
      DOI: 10.1002/adfm.201604944
  • Readdressing of Magnetoelectric Effect in Bulk BiFeO3
    • Authors: Xin Xin Shi; Xiao Qiang Liu, Xiang Ming Chen
      Abstract: After decades of study, BiFeO3 is still the most promising single-phase multiferroic material due to its large polarization and high operating temperature, drawing much attention. As a typical type-I multiferroic material, the magnetoelectric coupling in BiFeO3 is deemed to be weak due to the different origins of its ferroelectricity and magnetism. Here, the magnetoelectric effect in bulk BiFeO3 is readdressed both theoretically and experimentally. Based on the Dzyaloshinsky–Moriya interaction scenario, the magnetoelectric effect in BiFeO3 is actually strong, with a coupling energy of about 1.25 meV and a magnetism-coupled parasitic polarization comparable to that of the type-II multiferroics. However, such strong magnetoelectric coupling also causes the cycloidal spin structure, which inhibits the observation of linear magnetoelectric coupling in bulk BiFeO3. To resolve this contradiction, Sm-substitution is utilized to suppress the magnetoelectric effect and unlocks the weak ferromagnetism. At an optimized composition, such a weak ferromagnetic state can be switched back to the cycloidal state by an electric field, thus realizing electrical control of the magnetism. It has been argued that field-controlled phase transition is a promising path to colossal magnetoelectric effect. It is of pioneering significance for further investigations down this road.The present readdressing of the magnetoelectric effect in bulk BiFeO3 reveals that the strong magnetoelectric coupling and weak ferromagnetism are actually incompatible. To resolve such a contradiction, an electric-field-induced phase transition from the weak ferromagnetic state to the cycloidal spin state is focused and the concomitant reduction of the magnetization has been observed.
      PubDate: 2017-02-10T02:25:51.979026-05:
      DOI: 10.1002/adfm.201604037
  • High-Performance Oxygen Reduction Electrocatalyst Derived from
           Polydopamine and Cobalt Supported on Carbon Nanotubes for Metal–Air
    • Authors: Yiling Liu; Fengjiao Chen, Wen Ye, Min Zeng, Na Han, Feipeng Zhao, Xinxia Wang, Yanguang Li
      Abstract: The development of nonprecious metal-based electrocatalysts for the oxygen reduction reaction holds the decisive key to many energy conversion devices. Among several potential candidates, transition metal and nitrogen co-doped carbonaceous materials are the most promising, yet their activity and stability are still insufficient to meet the needs of practical applications. In this study, a core–shell hybrid electrocatalyst is developed via the self-polymerization of dopamine and cobalt on carbon nanotubes (CNTs), followed by high-temperature pyrolysis. The polymer-derived carbonaceous shell contains abundant structural defects and facilitates the formation of CoN/C active sites, whereas the graphitic carbon nanotube core provides high electrical conductivity and corrosion resistance. These two components separately fulfill different functionalities, and jointly afford the catalyst with excellent electrochemical performance. In 1 m KOH, CoN/CNT exhibits a positive half-wave potential of ≈0.91 V, low peroxide yield of
      PubDate: 2017-02-09T04:17:29.339858-05:
      DOI: 10.1002/adfm.201606034
  • Cellulose Nanocrystal Inks for 3D Printing of Textured Cellular
    • Authors: Gilberto Siqueira; Dimitri Kokkinis, Rafael Libanori, Michael K. Hausmann, Amelia Sydney Gladman, Antonia Neels, Philippe Tingaut, Tanja Zimmermann, Jennifer A. Lewis, André R. Studart
      Abstract: 3D printing of renewable building blocks like cellulose nanocrystals offers an attractive pathway for fabricating sustainable structures. Here, viscoelastic inks composed of anisotropic cellulose nanocrystals (CNC) that enable patterning of 3D objects by direct ink writing are designed and formulated. These concentrated inks are composed of CNC particles suspended in either water or a photopolymerizable monomer solution. The shear-induced alignment of these anisotropic building blocks during printing is quantified by atomic force microscopy, polarized light microscopy, and 2D wide-angle X-ray scattering measurements. Akin to the microreinforcing effect in plant cell walls, the alignment of CNC particles during direct writing yields textured composites with enhanced stiffness along the printing direction. The observations serve as an important step forward toward the development of sustainable materials for 3D printing of cellular architectures with tailored mechanical properties.Aqueous and polymer-based inks with high cellulose nanocrystal (CNC) loading are developed for 3D printing of textured cellular architectures. Alignment of CNC particles within the 3D printed filaments leads to enhanced mechanical properties along the printing direction, akin to wood and other biological composites.
      PubDate: 2017-02-07T07:36:04.759956-05:
      DOI: 10.1002/adfm.201604619
  • Naphthothiadiazole-Based Near-Infrared Emitter with a Photoluminescence
           Quantum Yield of 60% in Neat Film and External Quantum Efficiencies of up
           to 3.9% in Nondoped OLEDs
    • Authors: Tengxiao Liu; Liping Zhu, Cheng Zhong, Guohua Xie, Shaolong Gong, Junfeng Fang, Dongge Ma, Chuluo Yang
      Abstract: Fluorescent emitters have regained intensive attention in organic light emitting diode (OLED) community owing to the breakthrough of the device efficiency and/or new emitting mechanism. This provides a good chance to develop new near-infrared (NIR) fluorescent emitter and high-efficiency device. In this work, a D-π-A-π-D type compound with naphthothiadiazole as acceptor, namely, 4,4′-(naphtho[2,3-c][1,2,5]thiadiazole-4,9-diyl)bis(N,N-diphenylaniline) (NZ2TPA), is designed and synthesized. The photophysical study and density functional theory analysis reveal that the emission of the compound has obvious hybridized local and charge-transfer (HLCT) state feature. In addition, the compound shows aggregation-induced emission (AIE) characteristic. Attributed to its HLCT mechanism and AIE characteristic, NZ2TPA acquires an unprecedentedly high photoluminescent quantum yield of 60% in the neat film, which is the highest among the reported organic small-molecule NIR emitters and even exceeds most phosphorescent NIR materials. The nondoped devices based on NZ2TPA exhibit excellent performance, achieving a maximum external quantum efficiency (EQE) of 3.9% with the emission peak at 696 nm and a high luminance of 6330 cd m−2, which are among the highest in the reported nondoped NIR fluorescent OLEDs. Moreover, the device remains a high EQE of 2.8% at high brightness of 1000 cd m−2, with very low efficiency roll-off.A near-infrared small-molecule emitter exhibits an unprecedentedly high photoluminescent quantum yield of 60% with an emission peak of 683 nm in the neat film. The resulting nondoped organic light emitting diodes achieve a maximum external quantum efficiency of 3.9% with an emission peak of 696 nm.
      PubDate: 2017-02-07T07:35:58.818444-05:
      DOI: 10.1002/adfm.201606384
  • A Versatile Plasma Membrane Engineered Cell Vehicle for
           Contact-Cell-Enhanced Photodynamic Therapy
    • Authors: Shi-Ying Li; Wen-Xiu Qiu, Hong Cheng, Fan Gao, Feng-Yi Cao, Xian-Zheng Zhang
      Abstract: In this paper, a plasma membrane engineering approach is reported for tumor targeting drug delivery and contact-cell-enhanced photodynamic therapy (“CONCEPT”) by anchoring functionalized conjugates to cell vehicles. The membrane anchoring conjugates are comprised of a positively charged tetra-arginine peptide sequence, a palmitic-acid-based membrane insertion moiety, and a lysine linker whose ε-amine is modified with camptothecin (CPT), protoporphyrin IX (PpIX), or fluorescein (FAM). The amphipathic CPT, PpIX, or FAM conjugates (short as aCPT, aPpIX, or aFAM, respectively) can easily and steadily anchor or coanchor on the cell membrane of RAW264.7 cells (short as RCs), red blood cells, or mesenchymal stem cells. After anchoring aPpIX in RC cells, the tumor targeting ability and therapeutic effect of aPpIX-anchored RC cells (short as aPRCs) is demonstrated in vitro and in vivo. Importantly, aPRCs exhibit the “CONCEPT” effect, which can enhance the therapeutic efficacy and reduce side effects at the single cell level. Due to the good tumor-targeting ability, aPRCs can efficiently inhibit the tumor growth with no systemic toxicity after photoirradiation by photodynamic therapy.A versatile plasma-membrane-engineered cell vehicle is developed for tumor targeting drug delivery and contact-cell-enhanced photodynamic therapy. This versatile cell vehicle can facilitate the development of personalized treatment for simultaneous tumor theranostics and combination therapy in a more safe way.
      PubDate: 2017-02-07T07:30:45.75284-05:0
      DOI: 10.1002/adfm.201604916
  • Encapsulating a Hydrophilic Chemotherapeutic into Rod-Like Nanoparticles
           of a Genetically Encoded Asymmetric Triblock Polypeptide Improves Its
    • Authors: Jayanta Bhattacharyya; Isaac Weitzhandler, Shihan Bryan Ho, Jonathan R. McDaniel, Xinghai Li, Lei Tang, Jinyao Liu, Mark Dewhirst, Ashutosh Chilkoti
      Abstract: Encapsulating hydrophilic chemotherapeutics into the core of polymeric nanoparticles can improve their therapeutic efficacy by increasing their plasma half-life, tumor accumulation, and intracellular uptake, and by protecting them from premature degradation. To achieve these goals, a recombinant asymmetric triblock polypeptide (ATBP) that self-assembles into rod-shaped nanoparticles, and which can be used to conjugate diverse hydrophilic molecules, including chemotherapeutics, into their core is designed. These ATBPs consist of three segments: a biodegradable elastin-like polypeptide, a hydrophobic tyrosine-rich segment, and a short cysteine-rich segment, that spontaneously self-assemble into rod-shaped micelles. Covalent conjugation of a structurally diverse set of hydrophilic small molecules, including a hydrophilic chemotherapeutic—gemcitabine—to the cysteine residues also leads to formation of nanoparticles over a range of ATBP concentrations. Gemcitabine-loaded ATBP nanoparticles have significantly better tumor regression compared to free drug in a murine cancer model. This simple strategy of encapsulation of hydrophilic small molecules by conjugation to an ATBP can be used to effectively deliver a range of water-soluble drugs and imaging agents in vivo.Attachment of gemcitabine retains the self-assembly of the asymmetric triblock polypeptide into cylindrical nanoparticles with a drug-rich (blue diamonds) core surrounded by a hydrophobic core (red) and hydrophilic polypeptide corona (black chains).
      PubDate: 2017-02-07T07:25:35.205674-05:
      DOI: 10.1002/adfm.201605421
  • Dry Transient Electronic Systems by Use of Materials that Sublime
    • Authors: Bong Hoon Kim; Jae-Hwan Kim, Luana Persano, Suk-Won Hwang, Seungmin Lee, Jungyup Lee, Yongjoon Yu, Yongseon Kang, Sang M. Won, Jahyun Koo, Youn Kyoung Cho, Gyum Hur, Anthony Banks, Jun-Kyul Song, Phillip Won, Young Min Song, Kyung-In Jang, Daeshik Kang, Chi Hwan Lee, Dario Pisignano, John A. Rogers
      Abstract: The recent emergence of materials for electronic systems that are capable of programmable self-destruction and/or bio/eco-resorption creates the potential for important classes of devices that cannot be easily addressed using conventional technologies, ranging from temporary biomedical implants to enviromentally benign environmental monitors to hardware secure data systems. Although most previous demonstrations rely on wet chemistry to initiate transient processes of degradation/decomposition, options in “dry transient electronic systems” could expand the range of possible uses. The work presented here introduces materials and composite systems in which sublimation under ambient conditions leads to mechanical fragmentation and disintegration of active devices upon disappearance of a supporting substrate, encapsulation layer, interlayer dielectric and/or gate dielectric. Examples span arrays of transistors based on silicon nanomembranes with specialized device designs to solar cells adapted from commercial components.Unusual materials and device designs enable classes of electronic systems that undergo timed self-destruction induced by ambient sublimation of a supporting substrate, encapsulation layer, interlayer dielectric and/or gate dielectric followed by resulting fragmentation of the remaining ultrathin constituent material elements.
      PubDate: 2017-02-06T08:04:38.144677-05:
      DOI: 10.1002/adfm.201606008
  • High-Performance Photodetectors Based on Organometal Halide Perovskite
    • Authors: Wenhui Wang; Yurong Ma, Limin Qi
      Abstract: The booming development of organometal halide perovskites has prompted the exploration of morphology-engineering strategies to improve their performance in optoelectronic applications. However, the preparation of optoelectronic devices of perovskites with complex architectures and desirable properties is still highly challenging. Herein, novel CH3NH3PbI3 nanonets and nanobowl arrays are fabricated facilely by using monolayer colloidal crystal (MCC) templates on different substrates. Specifically, highly ordered CH3NH3PbI3 nanonets with high crystallinity are fabricated on a variety of flat substrates, whereas regular CH3NH3PbI3 nanobowl arrays are produced on a coarse substrate. The photodetection performance of the CH3NH3PbI3 nanonet-based photodetectors is significantly enhanced compared to the photodetectors based on conventional CH3NH3PbI3 compact films. Particularly, the nanonet photodetectors exhibit a high responsivity (10.33 A W−1 under 700 nm monochromatic light), which is six times higher than that for the compact CH3NH3PbI3 film devices, fast response speed, and good stability. Owing to the two-dimensional arrayed structure, the CH3NH3PbI3 nanonets exhibit an enhanced light harvesting ability and offer direct carrier transport pathways. Meanwhile, the MCC template brings about larger grain sizes with enhanced crystallinity. Furthermore, the perovskite nanonets can be formed on a flexible polyethylene terephthalate substrate for the fabrication of promising flexible nanonet photodetectors.Highly ordered CH3NH3PbI3 nanonets with high crystallinity are fabricated on a variety of flat substrates through a facile nanosphere lithography approach. When used as a photodetector, the perovskite nanonet exhibits significantly enhanced photoresponsive performance owing to the unique net-like architecture that is beneficial to light harvesting and charge collection.
      PubDate: 2017-02-06T08:01:07.650561-05:
      DOI: 10.1002/adfm.201603653
  • Two-Color Emitting Colloidal Nanocrystals as Single-Particle Ratiometric
           Probes of Intracellular pH
    • Authors: Francesco Bruni; Jacopo Pedrini, Caterina Bossio, Beatriz Santiago-Gonzalez, Francesco Meinardi, Wan Ki Bae, Victor I. Klimov, Guglielmo Lanzani, Sergio Brovelli
      Abstract: Intracellular pH is a key parameter in many biological mechanisms and cell metabolism and is used to detect and monitor cancer formation and brain or heart diseases. pH-sensing is typically performed by fluorescence microscopy using pH-responsive dyes. Accuracy is limited by the need for quantifying the absolute emission intensity in living biological samples. An alternative with a higher sensitivity and precision uses probes with a ratiometric response arising from the different pH-sensitivity of two emission channels of a single emitter. Current ratiometric probes are complex constructs suffering from instability and cross-readout due to their broad emission spectra. Here, we overcome such limitations using a single-particle ratiometric pH probe based on dot-in-bulk CdSe/CdS nanocrystals (NCs). These nanostructures feature two fully-separated narrow emissions with different pH sensitivity arising from radiative recombination of core- and shell-localized excitons. The core emission is nearly independent of the pH, whereas the shell luminescence increases in the 3–11 pH range, resulting in a cross-readout-free ratiometric response as strong as 600%. In vitro microscopy demonstrates that the ratiometric response in biologic media resembles the precalibralation curve obtained through far-field titration experiments. The NCs show good biocompatibility, enabling us to monitor in real-time the pH in living cells.Intracellular pH is a key parameter in biological mechanisms and cell metabolism. This study demonstrates single-particle ratiometric pH probes based on hetero-nanocrystals featuring two coexisting emission bands with pH sensitivity. In vitro microscopy demonstrates that the intracellular ratiometric response resembles the precalibration curve obtained through far-field experiments. The nanocrystals show good biocompatibility, enabling us to monitor externally induced pH variations in living cells.
      PubDate: 2017-02-06T07:55:47.491818-05:
      DOI: 10.1002/adfm.201605533
  • Gold Nanocomposite Bioink for Printing 3D Cardiac Constructs
    • Authors: Kai Zhu; Su Ryon Shin, Tim van Kempen, Yi-Chen Li, Vidhya Ponraj, Amir Nasajpour, Serena Mandla, Ning Hu, Xiao Liu, Jeroen Leijten, Yi-Dong Lin, Mohammad Asif Hussain, Yu Shrike Zhang, Ali Tamayol, Ali Khademhosseini
      Abstract: Bioprinting is the most convenient microfabrication method to create biomimetic three-dimensional (3D) cardiac tissue constructs, that can be used to regenerate damaged tissue and provide platforms for drug screening. However, existing bioinks, which are usually composed of polymeric biomaterials, are poorly conductive and delay efficient electrical coupling between adjacent cardiac cells. To solve this problem, a gold nanorod (GNR)-incorporated gelatin methacryloyl (GelMA)-based bioink is developed for printing 3D functional cardiac tissue constructs. The GNR concentration is adjusted to create a proper microenvironment for the spreading and organization of cardiac cells. At optimized concentrations of GNR, the nanocomposite bioink has a low viscosity, similar to pristine inks, which allows for the easy integration of cells at high densities. As a result, rapid deposition of cell-laden fibers at a high resolution is possible, while reducing shear stress on the encapsulated cells. In the printed GNR constructs, cardiac cells show improved cell adhesion and organization when compared to the constructs without GNRs. Furthermore, the incorporated GNRs bridge the electrically resistant pore walls of polymers, improve the cell-to-cell coupling, and promote synchronized contraction of the bioprinted constructs. Given its advantageous properties, this gold nanocomposite bioink may find wide application in cardiac tissue engineering.A gold nanorod-incorporated gelatin methacryloyl-based bioink for printing of 3D cardiac tissue constructs is developed. The rapid deposition of the cell-laden fibers at a high resolution is achieved, while reducing the shear stress on the encapsulated cells. The incorporated gold nanorods improve the electrical propagation between cardiac cells and promote their functional improvement in the printed cardiac construct.
      PubDate: 2017-01-17T06:00:52.792847-05:
      DOI: 10.1002/adfm.201605352
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