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Publisher: John Wiley and Sons   (Total: 1576 journals)

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Showing 1 - 200 of 1576 Journals sorted alphabetically
Abacus     Hybrid Journal   (Followers: 12, SJR: 0.48, h-index: 22)
About Campus     Hybrid Journal   (Followers: 5)
Academic Emergency Medicine     Hybrid Journal   (Followers: 58, SJR: 1.385, h-index: 91)
Accounting & Finance     Hybrid Journal   (Followers: 46, SJR: 0.547, h-index: 30)
ACEP NOW     Free   (Followers: 1)
Acta Anaesthesiologica Scandinavica     Hybrid Journal   (Followers: 51, SJR: 1.02, h-index: 88)
Acta Archaeologica     Hybrid Journal   (Followers: 139, SJR: 0.101, h-index: 9)
Acta Geologica Sinica (English Edition)     Hybrid Journal   (Followers: 3, SJR: 0.552, h-index: 41)
Acta Neurologica Scandinavica     Hybrid Journal   (Followers: 5, SJR: 1.203, h-index: 74)
Acta Obstetricia et Gynecologica Scandinavica     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 81)
Acta Ophthalmologica     Hybrid Journal   (Followers: 5, SJR: 0.112, h-index: 1)
Acta Paediatrica     Hybrid Journal   (Followers: 56, SJR: 0.794, h-index: 88)
Acta Physiologica     Hybrid Journal   (Followers: 6, SJR: 1.69, h-index: 88)
Acta Polymerica     Hybrid Journal   (Followers: 9)
Acta Psychiatrica Scandinavica     Hybrid Journal   (Followers: 35, SJR: 2.518, h-index: 113)
Acta Zoologica     Hybrid Journal   (Followers: 6, SJR: 0.459, h-index: 29)
Acute Medicine & Surgery     Hybrid Journal   (Followers: 2)
Addiction     Hybrid Journal   (Followers: 33, SJR: 2.086, h-index: 143)
Addiction Biology     Hybrid Journal   (Followers: 12, SJR: 2.091, h-index: 57)
Adultspan J.     Hybrid Journal   (SJR: 0.127, h-index: 4)
Advanced Energy Materials     Hybrid Journal   (Followers: 24, SJR: 6.411, h-index: 86)
Advanced Engineering Materials     Hybrid Journal   (Followers: 26, SJR: 0.81, h-index: 81)
Advanced Functional Materials     Hybrid Journal   (Followers: 50, SJR: 5.21, h-index: 203)
Advanced Healthcare Materials     Hybrid Journal   (Followers: 13, SJR: 0.232, h-index: 7)
Advanced Materials     Hybrid Journal   (Followers: 250, SJR: 9.021, h-index: 345)
Advanced Materials Interfaces     Hybrid Journal   (Followers: 6, SJR: 1.177, h-index: 10)
Advanced Optical Materials     Hybrid Journal   (Followers: 5, SJR: 2.488, h-index: 21)
Advanced Science     Open Access   (Followers: 5)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17, SJR: 2.729, h-index: 121)
Advances in Polymer Technology     Hybrid Journal   (Followers: 13, SJR: 0.344, h-index: 31)
Africa Confidential     Hybrid Journal   (Followers: 19)
Africa Research Bulletin: Economic, Financial and Technical Series     Hybrid Journal   (Followers: 12)
Africa Research Bulletin: Political, Social and Cultural Series     Hybrid Journal   (Followers: 9)
African Development Review     Hybrid Journal   (Followers: 35, SJR: 0.275, h-index: 17)
African J. of Ecology     Hybrid Journal   (Followers: 15, SJR: 0.477, h-index: 39)
Aggressive Behavior     Hybrid Journal   (Followers: 15, SJR: 1.391, h-index: 66)
Aging Cell     Open Access   (Followers: 10, SJR: 4.374, h-index: 95)
Agribusiness : an Intl. J.     Hybrid Journal   (Followers: 6, SJR: 0.627, h-index: 14)
Agricultural and Forest Entomology     Hybrid Journal   (Followers: 14, SJR: 0.925, h-index: 43)
Agricultural Economics     Hybrid Journal   (Followers: 44, SJR: 1.099, h-index: 51)
AIChE J.     Hybrid Journal   (Followers: 29, SJR: 1.122, h-index: 120)
Alcoholism and Drug Abuse Weekly     Hybrid Journal   (Followers: 7)
Alcoholism Clinical and Experimental Research     Hybrid Journal   (Followers: 7, SJR: 1.416, h-index: 125)
Alimentary Pharmacology & Therapeutics     Hybrid Journal   (Followers: 34, SJR: 2.833, h-index: 138)
Alimentary Pharmacology & Therapeutics Symposium Series     Hybrid Journal   (Followers: 3)
Allergy     Hybrid Journal   (Followers: 50, SJR: 3.048, h-index: 129)
Alternatives to the High Cost of Litigation     Hybrid Journal   (Followers: 3)
American Anthropologist     Hybrid Journal   (Followers: 128, SJR: 0.951, h-index: 61)
American Business Law J.     Hybrid Journal   (Followers: 24, SJR: 0.205, h-index: 17)
American Ethnologist     Hybrid Journal   (Followers: 91, SJR: 2.325, h-index: 51)
American J. of Economics and Sociology     Hybrid Journal   (Followers: 27, SJR: 0.211, h-index: 26)
American J. of Hematology     Hybrid Journal   (Followers: 31, SJR: 1.761, h-index: 77)
American J. of Human Biology     Hybrid Journal   (Followers: 12, SJR: 1.018, h-index: 58)
American J. of Industrial Medicine     Hybrid Journal   (Followers: 16, SJR: 0.993, h-index: 85)
American J. of Medical Genetics Part A     Hybrid Journal   (Followers: 15, SJR: 1.115, h-index: 61)
American J. of Medical Genetics Part B: Neuropsychiatric Genetics     Hybrid Journal   (Followers: 3, SJR: 1.771, h-index: 107)
American J. of Medical Genetics Part C: Seminars in Medical Genetics     Partially Free   (Followers: 5, SJR: 2.315, h-index: 79)
American J. of Physical Anthropology     Hybrid Journal   (Followers: 36, SJR: 1.41, h-index: 88)
American J. of Political Science     Hybrid Journal   (Followers: 250, SJR: 5.101, h-index: 114)
American J. of Primatology     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 63)
American J. of Reproductive Immunology     Hybrid Journal   (Followers: 3, SJR: 1.347, h-index: 75)
American J. of Transplantation     Hybrid Journal   (Followers: 16, SJR: 2.792, h-index: 140)
American J. on Addictions     Hybrid Journal   (Followers: 9, SJR: 0.843, h-index: 57)
Anaesthesia     Hybrid Journal   (Followers: 120, SJR: 1.404, h-index: 88)
Analyses of Social Issues and Public Policy     Hybrid Journal   (Followers: 11, SJR: 0.397, h-index: 18)
Analytic Philosophy     Hybrid Journal   (Followers: 16)
Anatomia, Histologia, Embryologia: J. of Veterinary Medicine Series C     Hybrid Journal   (Followers: 3, SJR: 0.295, h-index: 27)
Anatomical Sciences Education     Hybrid Journal   (Followers: 1, SJR: 0.633, h-index: 24)
Andrologia     Hybrid Journal   (Followers: 2, SJR: 0.528, h-index: 45)
Andrology     Hybrid Journal   (Followers: 2, SJR: 0.979, h-index: 14)
Angewandte Chemie     Hybrid Journal   (Followers: 161)
Angewandte Chemie Intl. Edition     Hybrid Journal   (Followers: 209, SJR: 6.229, h-index: 397)
Animal Conservation     Hybrid Journal   (Followers: 35, SJR: 1.576, h-index: 62)
Animal Genetics     Hybrid Journal   (Followers: 8, SJR: 0.957, h-index: 67)
Animal Science J.     Hybrid Journal   (Followers: 6, SJR: 0.569, h-index: 24)
Annalen der Physik     Hybrid Journal   (Followers: 5, SJR: 1.46, h-index: 40)
Annals of Anthropological Practice     Partially Free   (Followers: 2, SJR: 0.187, h-index: 5)
Annals of Applied Biology     Hybrid Journal   (Followers: 8, SJR: 0.816, h-index: 56)
Annals of Clinical and Translational Neurology     Open Access   (Followers: 1)
Annals of Human Genetics     Hybrid Journal   (Followers: 9, SJR: 1.191, h-index: 67)
Annals of Neurology     Hybrid Journal   (Followers: 44, SJR: 5.584, h-index: 241)
Annals of Noninvasive Electrocardiology     Hybrid Journal   (Followers: 2, SJR: 0.531, h-index: 38)
Annals of Public and Cooperative Economics     Hybrid Journal   (Followers: 9, SJR: 0.336, h-index: 23)
Annals of the New York Academy of Sciences     Hybrid Journal   (Followers: 5, SJR: 2.389, h-index: 189)
Annual Bulletin of Historical Literature     Hybrid Journal   (Followers: 12)
Annual Review of Information Science and Technology     Hybrid Journal   (Followers: 14)
Anthropology & Education Quarterly     Hybrid Journal   (Followers: 24, SJR: 0.72, h-index: 31)
Anthropology & Humanism     Hybrid Journal   (Followers: 16, SJR: 0.137, h-index: 3)
Anthropology News     Hybrid Journal   (Followers: 14)
Anthropology of Consciousness     Hybrid Journal   (Followers: 11, SJR: 0.172, h-index: 5)
Anthropology of Work Review     Hybrid Journal   (Followers: 11, SJR: 0.256, h-index: 5)
Anthropology Today     Hybrid Journal   (Followers: 93, SJR: 0.545, h-index: 15)
Antipode     Hybrid Journal   (Followers: 45, SJR: 2.212, h-index: 69)
Anz J. of Surgery     Hybrid Journal   (Followers: 6, SJR: 0.432, h-index: 59)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apmis     Hybrid Journal   (Followers: 1, SJR: 0.855, h-index: 73)
Applied Cognitive Psychology     Hybrid Journal   (Followers: 67, SJR: 0.754, h-index: 69)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7, SJR: 0.632, h-index: 58)
Applied Psychology     Hybrid Journal   (Followers: 136, SJR: 1.023, h-index: 64)
Applied Psychology: Health and Well-Being     Hybrid Journal   (Followers: 48, SJR: 0.868, h-index: 13)
Applied Stochastic Models in Business and Industry     Hybrid Journal   (Followers: 5, SJR: 0.613, h-index: 24)
Aquaculture Nutrition     Hybrid Journal   (Followers: 14, SJR: 1.025, h-index: 55)
Aquaculture Research     Hybrid Journal   (Followers: 31, SJR: 0.807, h-index: 60)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 34, SJR: 1.047, h-index: 57)
Arabian Archaeology and Epigraphy     Hybrid Journal   (Followers: 11, SJR: 0.453, h-index: 11)
Archaeological Prospection     Hybrid Journal   (Followers: 12, SJR: 0.922, h-index: 21)
Archaeology in Oceania     Hybrid Journal   (Followers: 13, SJR: 0.745, h-index: 18)
Archaeometry     Hybrid Journal   (Followers: 27, SJR: 0.809, h-index: 48)
Archeological Papers of The American Anthropological Association     Hybrid Journal   (Followers: 14, SJR: 0.156, h-index: 2)
Architectural Design     Hybrid Journal   (Followers: 25, SJR: 0.261, h-index: 9)
Archiv der Pharmazie     Hybrid Journal   (Followers: 4, SJR: 0.628, h-index: 43)
Archives of Drug Information     Hybrid Journal   (Followers: 4)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (SJR: 0.768, h-index: 54)
Area     Hybrid Journal   (Followers: 12, SJR: 0.938, h-index: 57)
Art History     Hybrid Journal   (Followers: 218, SJR: 0.153, h-index: 13)
Arthritis & Rheumatology     Hybrid Journal   (Followers: 51, SJR: 1.984, h-index: 20)
Arthritis Care & Research     Hybrid Journal   (Followers: 28, SJR: 2.256, h-index: 114)
Artificial Organs     Hybrid Journal   (Followers: 1, SJR: 0.872, h-index: 60)
ASHE Higher Education Reports     Hybrid Journal   (Followers: 14)
Asia & the Pacific Policy Studies     Open Access   (Followers: 14)
Asia Pacific J. of Human Resources     Hybrid Journal   (Followers: 315, SJR: 0.494, h-index: 19)
Asia Pacific Viewpoint     Hybrid Journal   (SJR: 0.616, h-index: 26)
Asia-Pacific J. of Chemical Engineering     Hybrid Journal   (Followers: 7, SJR: 0.345, h-index: 20)
Asia-pacific J. of Clinical Oncology     Hybrid Journal   (Followers: 6, SJR: 0.554, h-index: 14)
Asia-Pacific J. of Financial Studies     Hybrid Journal   (SJR: 0.241, h-index: 7)
Asia-Pacific Psychiatry     Hybrid Journal   (Followers: 3, SJR: 0.377, h-index: 7)
Asian Economic J.     Hybrid Journal   (Followers: 8, SJR: 0.234, h-index: 21)
Asian Economic Policy Review     Hybrid Journal   (Followers: 4, SJR: 0.196, h-index: 12)
Asian J. of Control     Hybrid Journal   (SJR: 0.862, h-index: 34)
Asian J. of Endoscopic Surgery     Hybrid Journal   (SJR: 0.394, h-index: 7)
Asian J. of Organic Chemistry     Hybrid Journal   (Followers: 4, SJR: 1.443, h-index: 19)
Asian J. of Social Psychology     Hybrid Journal   (Followers: 5, SJR: 0.665, h-index: 37)
Asian Politics and Policy     Hybrid Journal   (Followers: 13, SJR: 0.207, h-index: 7)
Asian Social Work and Policy Review     Hybrid Journal   (Followers: 5, SJR: 0.318, h-index: 5)
Asian-pacific Economic Literature     Hybrid Journal   (Followers: 5, SJR: 0.168, h-index: 15)
Assessment Update     Hybrid Journal   (Followers: 4)
Astronomische Nachrichten     Hybrid Journal   (Followers: 2, SJR: 0.701, h-index: 40)
Atmospheric Science Letters     Open Access   (Followers: 29, SJR: 1.332, h-index: 27)
Austral Ecology     Hybrid Journal   (Followers: 12, SJR: 1.095, h-index: 66)
Austral Entomology     Hybrid Journal   (Followers: 10, SJR: 0.524, h-index: 28)
Australasian J. of Dermatology     Hybrid Journal   (Followers: 8, SJR: 0.714, h-index: 40)
Australasian J. On Ageing     Hybrid Journal   (Followers: 7, SJR: 0.39, h-index: 22)
Australian & New Zealand J. of Statistics     Hybrid Journal   (Followers: 13, SJR: 0.275, h-index: 28)
Australian Accounting Review     Hybrid Journal   (Followers: 4, SJR: 0.709, h-index: 14)
Australian and New Zealand J. of Family Therapy (ANZJFT)     Hybrid Journal   (Followers: 3, SJR: 0.382, h-index: 12)
Australian and New Zealand J. of Obstetrics and Gynaecology     Hybrid Journal   (Followers: 43, SJR: 0.814, h-index: 49)
Australian and New Zealand J. of Public Health     Hybrid Journal   (Followers: 11, SJR: 0.82, h-index: 62)
Australian Dental J.     Hybrid Journal   (Followers: 6, SJR: 0.482, h-index: 46)
Australian Economic History Review     Hybrid Journal   (Followers: 4, SJR: 0.171, h-index: 12)
Australian Economic Papers     Hybrid Journal   (Followers: 23, SJR: 0.23, h-index: 9)
Australian Economic Review     Hybrid Journal   (Followers: 6, SJR: 0.357, h-index: 21)
Australian Endodontic J.     Hybrid Journal   (Followers: 3, SJR: 0.513, h-index: 24)
Australian J. of Agricultural and Resource Economics     Hybrid Journal   (Followers: 3, SJR: 0.765, h-index: 36)
Australian J. of Grape and Wine Research     Hybrid Journal   (Followers: 5, SJR: 0.879, h-index: 56)
Australian J. of Politics & History     Hybrid Journal   (Followers: 13, SJR: 0.203, h-index: 14)
Australian J. of Psychology     Hybrid Journal   (Followers: 18, SJR: 0.384, h-index: 30)
Australian J. of Public Administration     Hybrid Journal   (Followers: 392, SJR: 0.418, h-index: 29)
Australian J. of Rural Health     Hybrid Journal   (Followers: 4, SJR: 0.43, h-index: 34)
Australian Occupational Therapy J.     Hybrid Journal   (Followers: 66, SJR: 0.59, h-index: 29)
Australian Psychologist     Hybrid Journal   (Followers: 11, SJR: 0.331, h-index: 31)
Australian Veterinary J.     Hybrid Journal   (Followers: 19, SJR: 0.459, h-index: 45)
Autism Research     Hybrid Journal   (Followers: 31, SJR: 2.126, h-index: 39)
Autonomic & Autacoid Pharmacology     Hybrid Journal   (SJR: 0.371, h-index: 29)
Banks in Insurance Report     Hybrid Journal   (Followers: 1)
Basic & Clinical Pharmacology & Toxicology     Hybrid Journal   (Followers: 10, SJR: 0.539, h-index: 70)
Basic and Applied Pathology     Open Access   (Followers: 2, SJR: 0.113, h-index: 4)
Basin Research     Hybrid Journal   (Followers: 4, SJR: 1.54, h-index: 60)
Bauphysik     Hybrid Journal   (Followers: 2, SJR: 0.194, h-index: 5)
Bauregelliste A, Bauregelliste B Und Liste C     Hybrid Journal  
Bautechnik     Hybrid Journal   (Followers: 1, SJR: 0.321, h-index: 11)
Behavioral Interventions     Hybrid Journal   (Followers: 9, SJR: 0.297, h-index: 23)
Behavioral Sciences & the Law     Hybrid Journal   (Followers: 23, SJR: 0.736, h-index: 57)
Berichte Zur Wissenschaftsgeschichte     Hybrid Journal   (Followers: 9, SJR: 0.11, h-index: 5)
Beton- und Stahlbetonbau     Hybrid Journal   (Followers: 2, SJR: 0.493, h-index: 14)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 6, SJR: 0.311, h-index: 26)
Bioelectromagnetics     Hybrid Journal   (Followers: 1, SJR: 0.568, h-index: 64)
Bioengineering & Translational Medicine     Open Access  
BioEssays     Hybrid Journal   (Followers: 10, SJR: 3.104, h-index: 155)
Bioethics     Hybrid Journal   (Followers: 14, SJR: 0.686, h-index: 39)
Biofuels, Bioproducts and Biorefining     Hybrid Journal   (Followers: 1, SJR: 1.725, h-index: 56)
Biological J. of the Linnean Society     Hybrid Journal   (Followers: 15, SJR: 1.172, h-index: 90)
Biological Reviews     Hybrid Journal   (Followers: 3, SJR: 6.469, h-index: 114)
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 42, SJR: 0.12, h-index: 1)
Biology of the Cell     Full-text available via subscription   (Followers: 9, SJR: 1.812, h-index: 69)
Biomedical Chromatography     Hybrid Journal   (Followers: 6, SJR: 0.572, h-index: 49)
Biometrical J.     Hybrid Journal   (Followers: 5, SJR: 0.784, h-index: 44)
Biometrics     Hybrid Journal   (Followers: 37, SJR: 1.906, h-index: 96)
Biopharmaceutics and Drug Disposition     Hybrid Journal   (Followers: 10, SJR: 0.715, h-index: 44)
Biopolymers     Hybrid Journal   (Followers: 18, SJR: 1.199, h-index: 104)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 45, SJR: 0.415, h-index: 55)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 133, SJR: 1.633, h-index: 146)
Biotechnology J.     Hybrid Journal   (Followers: 13, SJR: 1.185, h-index: 51)
Biotechnology Progress     Hybrid Journal   (Followers: 39, SJR: 0.736, h-index: 101)
Biotropica     Hybrid Journal   (Followers: 18, SJR: 1.374, h-index: 71)
Bipolar Disorders     Hybrid Journal   (Followers: 10, SJR: 2.592, h-index: 100)
Birth     Hybrid Journal   (Followers: 34, SJR: 0.763, h-index: 64)
Birth Defects Research Part A : Clinical and Molecular Teratology     Hybrid Journal   (Followers: 2, SJR: 0.727, h-index: 77)
Birth Defects Research Part B: Developmental and Reproductive Toxicology     Hybrid Journal   (Followers: 5, SJR: 0.468, h-index: 47)
Birth Defects Research Part C : Embryo Today : Reviews     Hybrid Journal   (SJR: 1.513, h-index: 55)
BJOG : An Intl. J. of Obstetrics and Gynaecology     Partially Free   (Followers: 219, SJR: 2.083, h-index: 125)

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Journal Cover Advanced Materials
  [SJR: 9.021]   [H-I: 345]   [250 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0935-9648 - ISSN (Online) 1521-4095
   Published by John Wiley and Sons Homepage  [1576 journals]
  • Transparent, Flexible, and Conductive 2D Titanium Carbide (MXene) Films
           with High Volumetric Capacitance
    • Authors: Chuanfang (John) Zhang; Babak Anasori, Andrés Seral-Ascaso, Sang-Hoon Park, Niall McEvoy, Aleksey Shmeliov, Georg S. Duesberg, Jonathan N. Coleman, Yury Gogotsi, Valeria Nicolosi
      Abstract: 2D transition-metal carbides and nitrides, known as MXenes, have displayed promising properties in numerous applications, such as energy storage, electromagnetic interference shielding, and catalysis. Titanium carbide MXene (Ti3C2Tx), in particular, has shown significant energy-storage capability. However, previously, only micrometer-thick, nontransparent films were studied. Here, highly transparent and conductive Ti3C2Tx films and their application as transparent, solid-state supercapacitors are reported. Transparent films are fabricated via spin-casting of Ti3C2Tx nanosheet colloidal solutions, followed by vacuum annealing at 200 °C. Films with transmittance of 93% (≈4 nm) and 29% (≈88 nm) demonstrate DC conductivity of ≈5736 and ≈9880 S cm−1, respectively. Such highly transparent, conductive Ti3C2Tx films display impressive volumetric capacitance (676 F cm−3) combined with fast response. Transparent solid-state, asymmetric supercapacitors (72% transmittance) based on Ti3C2Tx and single-walled carbon nanotube (SWCNT) films are also fabricated. These electrodes exhibit high capacitance (1.6 mF cm−2) and energy density (0.05 µW h cm−2), and long lifetime (no capacitance decay over 20 000 cycles), exceeding that of graphene or SWCNT-based transparent supercapacitor devices. Collectively, the Ti3C2Tx films are among the state-of-the-art for future transparent, conductive, capacitive electrodes, and translate into technologically viable devices for next-generation wearable, portable electronics.Highly transparent and conductive Ti3C2Tx films and their application as transparent, solid-state supercapacitors are demonstrated. Films with transmittance of 93% (≈4 nm) and 29% (≈88 nm) demonstrate DC conductivity of ≈5736 and ≈9880 S cm−1, respectively. The Ti3C2Tx films display impressive volumetric capacitance (676 F cm−3), high areal capacitance, and long lifetime in the transparent solid-state supercapacitor devices.
      PubDate: 2017-07-25T01:26:54.994657-05:
      DOI: 10.1002/adma.201702678
       
  • Hollow MXene Spheres and 3D Macroporous MXene Frameworks for Na-Ion
           Storage
    • Authors: Meng-Qiang Zhao; Xiuqiang Xie, Chang E. Ren, Taron Makaryan, Babak Anasori, Guoxiu Wang, Yury Gogotsi
      Abstract: 2D transition metal carbides and nitrides, named MXenes, are attracting increasing attentions and showing competitive performance in energy storage devices including electrochemical capacitors, lithium- and sodium-ion batteries, and lithium–sulfur batteries. However, similar to other 2D materials, MXene nanosheets are inclined to stack together, limiting the device performance. In order to fully utilize MXenes' electrochemical energy storage capability, here, processing of 2D MXene flakes into hollow spheres and 3D architectures via a template method is reported. The MXene hollow spheres are stable and can be easily dispersed in solvents such as water and ethanol, demonstrating their potential applications in environmental and biomedical fields as well. The 3D macroporous MXene films are free-standing, flexible, and highly conductive due to good contacts between spheres and metallic conductivity of MXenes. When used as anodes for sodium-ion storage, these 3D MXene films exhibit much improved performances compared to multilayer MXenes and MXene/carbon nanotube hybrid architectures in terms of capacity, rate capability, and cycling stability. This work demonstrates the importance of MXene electrode architecture on the electrochemical performance and can guide future work on designing high-performance MXene-based materials for energy storage, catalysis, environmental, and biomedical applications.Hollow Ti3C2Tx spheres and 3D macroporous MXene films are fabricated using a sacrificial template approach. The 3D MXene films are free-standing, flexible, and highly conductive. They can serve directly as electrodes for Na-ion storage and exhibit high capacities accompanied with excellent stabilities and rate performance.
      PubDate: 2017-07-25T01:26:18.086544-05:
      DOI: 10.1002/adma.201702410
       
  • Reversible, Fast, and Wide-Range Oxygen Sensor Based on Nanostructured
           Organometal Halide Perovskite
    • Authors: Marc-Antoine Stoeckel; Marco Gobbi, Sara Bonacchi, Fabiola Liscio, Laura Ferlauto, Emanuele Orgiu, Paolo Samorì
      Abstract: Nanostructured materials characterized by high surface–volume ratio hold the promise to constitute the active materials for next-generation sensors. Solution-processed hybrid organohalide perovskites, which have been extensively used in the last few years for optoelectronic applications, are characterized by a self-assembled nanostructured morphology, which makes them an ideal candidate for gas sensing. Hitherto, detailed studies of the dependence of their electrical characteristics on the environmental atmosphere have not been performed, and even the effect of a ubiquitous gas such as O2 has been widely overlooked. Here, the electrical response of organohalide perovskites to oxygen is studied. Surprisingly, a colossal increase (3000-fold) in the resistance of perovskite-based lateral devices is found when measured in a full oxygen atmosphere, which is ascribed to a trap healing mechanism originating from an O2-mediated iodine vacancies filling. A variation as small as 70 ppm in the oxygen concentration can be detected. The effect is fast (
      PubDate: 2017-07-25T01:25:44.872874-05:
      DOI: 10.1002/adma.201702469
       
  • Porous Organic Polymers for Post-Combustion Carbon Capture
    • Authors: Lanfang Zou; Yujia Sun, Sai Che, Xinyu Yang, Xuan Wang, Matheiu Bosch, Qi Wang, Hao Li, Mallory Smith, Shuai Yuan, Zachary Perry, Hong-Cai Zhou
      Abstract: One of the most pressing environmental concerns of our age is the escalating level of atmospheric CO2. Intensive efforts have been made to investigate advanced porous materials, especially porous organic polymers (POPs), as one type of the most promising candidates for carbon capture due to their extremely high porosity, structural diversity, and physicochemical stability. This review provides a critical and in-depth analysis of recent POP research as it pertains to carbon capture. The definitions and terminologies commonly used to evaluate the performance of POPs for carbon capture, including CO2 capacity, enthalpy, selectivity, and regeneration strategies, are summarized. A detailed correlation study between the structural and chemical features of POPs and their adsorption capacities is discussed, mainly focusing on the physical interactions and chemical reactions. Finally, a concise outlook for utilizing POPs for carbon capture is discussed, noting areas in which further work is needed to develop the next-generation POPs for practical applications.Significant progress has been made in the exploration of porous organic polymers (POPs) as potential porous solid adsorbents for carbon capture. A detailed correlation study between the structural and chemical features of POPs and their adsorption capacities is discussed, mainly focusing on physical interactions and chemical reactions.
      PubDate: 2017-07-25T01:17:16.512696-05:
      DOI: 10.1002/adma.201700229
       
  • Superparamagnetic Gold Nanoparticles Synthesized on Protein Particle
           Scaffolds for Cancer Theragnosis
    • Authors: Koo Chul Kwon; Eunji Jo, Young-Wan Kwon, Boram Lee, Ju Hee Ryu, Eun Jung Lee, Kwangmeyung Kim, Jeewon Lee
      Abstract: Cancer theragnosis using a single multimodality agent is the next mainstay of modern cancer diagnosis, treatment, and management, but a clinically feasible agent with in vivo cancer targeting and theragnostic efficacy has not yet been developed. A new type of cancer theragnostic agent is reported, based on gold magnetism that is induced on a cancer-targeting protein particle carrier. Superparamagnetic gold-nanoparticle clusters (named SPAuNCs) are synthesized on a viral capsid particle that is engineered to present peptide ligands targeting a tumor cell receptor (TCR). The potent multimodality of the SPAuNCs is observed, which enables TCR-specific targeting, T2-weighted magnetic resonance imaging, and magnetic hyperthermia therapy of both subcutaneous and deep-tissue tumors in live mice under an alternating magnetic field. Furthermore, it is analytically elucidated how the magnetism of the SPAuNCs is sufficiently induced between localized and delocalized spins of Au atoms. In particular, the SPAuNCs show excellent biocompatibility without the problem of in vivo accumulation and holds promising potential as a clinically effective agent for cancer theragnosis.Superparamagnetic gold nanoparticle clusters (SPAuNCs) show a potent multimodality for targeted cancer theragnosis. They enable receptor-specific targeting, T2-weighted magnetic resonance imaging, and magnetic hyperthermia therapy of subcutaneous and deep-tissue tumors in live mice under an alternating magnetic field. In particular, SPAuNCs show excellent biocompatibility without the problem of in vivo accumulation and hold promising potential as a clinically effective agent for cancer theragnosis.
      PubDate: 2017-07-25T01:11:17.255777-05:
      DOI: 10.1002/adma.201701146
       
  • Protected Lithium-Metal Anodes in Batteries: From Liquid to Solid
    • Authors: Chunpeng Yang; Kun Fu, Ying Zhang, Emily Hitz, Liangbing Hu
      Abstract: High-energy lithium-metal batteries are among the most promising candidates for next-generation energy storage systems. With a high specific capacity and a low reduction potential, the Li-metal anode has attracted extensive interest for decades. Dendritic Li formation, uncontrolled interfacial reactions, and huge volume effect are major hurdles to the commercial application of Li-metal anodes. Recent studies have shown that the performance and safety of Li-metal anodes can be significantly improved via organic electrolyte modification, Li-metal interface protection, Li-electrode framework design, separator coating, and so on. Superior to the liquid electrolytes, solid-state electrolytes are considered able to inhibit problematic Li dendrites and build safe solid Li-metal batteries. Inspired by the bright prospects of solid Li-metal batteries, increasing efforts have been devoted to overcoming the obstacles of solid Li-metal batteries, such as low ionic conductivity of the electrolyte and Li–electrolyte interfacial problems. Here, the approaches to protect Li-metal anodes from liquid batteries to solid-state batteries are outlined and analyzed in detail. Perspectives regarding the strategies for developing Li-metal anodes are discussed to facilitate the practical application of Li-metal batteries.Lithium-metal batteries are promising candidates for high-energy and cost-effective energy-storage systems. Solving the dendritic problem and interfacial instability of the Li-metal anodes is a prerequisite to their practical utilization. Strategies to protect Li-metal anodes in liquid and solid-state electrolytes, which will facilitate the development safe and high-performance Li-metal batteries, are reviewed.
      PubDate: 2017-07-24T15:25:17.783351-05:
      DOI: 10.1002/adma.201701169
       
  • Vacancy-Driven Gelation Using Defect-Rich Nanoassemblies of 2D Transition
           Metal Dichalcogenides and Polymeric Binder for Biomedical Applications
    • Authors: Manish K. Jaiswal; James K. Carrow, James L. Gentry, Jagriti Gupta, Nara Altangerel, Marlan Scully, Akhilesh K. Gaharwar
      Abstract: A new approach of vacancy-driven gelation to obtain chemically crosslinked hydrogels from defect-rich 2D molybdenum disulfide (MoS2) nanoassemblies and polymeric binder is reported. This approach utilizes the planar and edge atomic defects available on the surface of the 2D MoS2 nanoassemblies to form mechanically resilient and elastomeric nanocomposite hydrogels. The atomic defects present on the lattice plane of 2D MoS2 nanoassemblies are due to atomic vacancies and can act as an active center for vacancy-driven gelation with a thiol-activated terminal such as four-arm poly(ethylene glycol)–thiol (PEG-SH) via chemisorption. By modulating the number of vacancies on the 2D MoS2 nanoassemblies, the physical and chemical properties of the hydrogel network can be controlled. This vacancy-driven gelation process does not require external stimuli such as UV exposure, chemical initiator, or thermal agitation for crosslinking and thus provides a nontoxic and facile approach to encapsulate cells and proteins. 2D MoS2 nanoassemblies are cytocompatible, and encapsulated cells in the nanocomposite hydrogels show high viability. Overall, the nanoengineered hydrogel obtained from vacancy-driven gelation is mechanically resilient and can be used for a range of biomedical applications including tissue engineering, regenerative medicine, and cell and therapeutic delivery.A new approach of vacancy-driven gelation to obtain chemically crosslinked hydrogels from defect-rich nanoassemblies of 2D transition metal dichalcogenides and polymeric binder is presented. The approach utilizes planar and edge atomic defects available on the surface of 2D MoS2 to form a chemically reinforced mechanically resilient nanocomposite network. Mechanically stiff and elastomeric nanocomposites hydrogels can be used to encapsulate cells for biomedical applications.
      PubDate: 2017-07-24T15:22:06.619175-05:
      DOI: 10.1002/adma.201702037
       
  • Direct Observation of Inherent Atomic-Scale Defect Disorders responsible
           for High-Performance Ti1−xHfxNiSn1−ySby Half-Heusler Thermoelectric
           Alloys
    • Authors: Ki Sung Kim; Young-Min Kim, Hyeona Mun, Jisoo Kim, Jucheol Park, Albina Y. Borisevich, Kyu Hyoung Lee, Sung Wng Kim
      Abstract: Structural defects often dominate the electronic- and thermal-transport properties of thermoelectric (TE) materials and are thus a central ingredient for improving their performance. However, understanding the relationship between TE performance and the disordered atomic defects that are generally inherent in nanostructured alloys remains a challenge. Herein, the use of scanning transmission electron microscopy to visualize atomic defects directly is described and disordered atomic-scale defects are demonstrated to be responsible for the enhancement of TE performance in nanostructured Ti1−xHfxNiSn1−ySby half-Heusler alloys. The disordered defects at all atomic sites induce a local composition fluctuation, effectively scattering phonons and improving the power factor. It is observed that the Ni interstitial and Ti,Hf/Sn antisite defects are collectively formed, leading to significant atomic disorder that causes the additional reduction of lattice thermal conductivity. The Ti1−xHfxNiSn1−ySby alloys containing inherent atomic-scale defect disorders are produced in one hour by a newly developed process of temperature-regulated rapid solidification followed by sintering. The collective atomic-scale defect disorder improves the zT to 1.09 ± 0.12 at 800 K for the Ti0.5Hf0.5NiSn0.98Sb0.02 alloy. These results provide a promising avenue for improving the TE performance of state-of-the-art materials.Disordered defects at all atomic sites induce a local composition fluctuation, effectively scattering phonons and improving power factors. Direct observation of atomic-scale defect disorders clarifies an enhancement of thermoelectric performance originating from a significant reduction of thermal conductivity in half-Heulser alloys. The collective atomic-scale defect disorder improves the zT to 1.09 ± 0.12 at 800 K for the Ti0.5Hf0.5NiSn0.98Sb0.02 alloy.
      PubDate: 2017-07-24T07:11:31.116819-05:
      DOI: 10.1002/adma.201702091
       
  • Multicellular Vascularized Engineered Tissues through User-Programmable
           Biomaterial Photodegradation
    • Authors: Christopher K. Arakawa; Barry A. Badeau, Ying Zheng, Cole A. DeForest
      Abstract: A photodegradable material-based approach to generate endothelialized 3D vascular networks within cell-laden hydrogel biomaterials is introduced. Exploiting multiphoton lithography, microchannel networks spanning nearly all size scales of native human vasculature are readily generated with unprecedented user-defined 4D control. Intraluminal channel architectures of synthetic vessels are fully customizable, providing new opportunities for next-generation microfluidics and directed cell function.A photodegradable material-based approach to generate endothelialized 3D vascular networks within cell-laden hydrogel biomaterials is introduced. Exploiting multiphoton lithography, microchannel networks spanning size scales of nearly all native human vasculature are readily generated with unprecedented user-defined 4D control. Intraluminal channel architectures of synthetic vessels are fully customizable, providing new opportunities for next-generation microfluidics and directed cell function.
      PubDate: 2017-07-24T07:07:31.270641-05:
      DOI: 10.1002/adma.201703156
       
  • Promising Thermoelectric Bulk Materials with 2D Structures
    • Authors: Yiming Zhou; Li-Dong Zhao
      Abstract: Given that more than two thirds of all energy is lost, mostly as waste heat, in utilization processes worldwide, thermoelectric materials, which can directly convert waste heat to electricity, provide an alternative option for optimizing energy utilization processes. After the prediction that superlattices may show high thermoelectric performance, various methods based on quantum effects and superlattice theory have been adopted to analyze bulk materials, leading to the rapid development of thermoelectric materials. Bulk materials with two-dimensional (2D) structures show outstanding properties, and their high performance originates from both their low thermal conductivity and high Seebeck coefficient due to their strong anisotropic features. Here, the advantages of superlattices for enhancing the thermoelectric performance, the transport mechanism in bulk materials with 2D structures, and optimization methods are discussed. The phenomenological transport mechanism in these materials indicates that thermal conductivities are reduced in 2D materials with intrinsically short mean free paths. Recent progress in the transport mechanisms of Bi2Te3-, SnSe-, and BiCuSeO-based systems is summarized. Finally, possible research directions to enhance the thermoelectric performance of bulk materials with 2D structures are briefly considered.Thermoelectric bulk materials with 2D structures possess natural structures similar to artificial superlattices, hence enabling the utilization of enhancement methods for superlattices. General optimization methods for Bi2Te3 are reviewed; meanwhile, the progress of advanced research into SnSe and BiCuSeO as promising thermoelectric materials is summarized.
      PubDate: 2017-07-24T07:06:39.592089-05:
      DOI: 10.1002/adma.201702676
       
  • Laser-Induced Graphene Formation on Wood
    • Authors: Ruquan Ye; Yieu Chyan, Jibo Zhang, Yilun Li, Xiao Han, Carter Kittrell, James M. Tour
      Abstract: Wood as a renewable naturally occurring resource has been the focus of much research and commercial interests in applications ranging from building construction to chemicals production. Here, a facile approach is reported to transform wood into hierarchical porous graphene using CO2 laser scribing. Studies reveal that the crosslinked lignocellulose structure inherent in wood with higher lignin content is more favorable for the generation of high-quality graphene than wood with lower lignin content. Because of its high electrical conductivity (≈10 Ω per square), graphene patterned on wood surfaces can be readily fabricated into various high-performance devices, such as hydrogen evolution and oxygen evolution electrodes for overall water splitting with high reaction rates at low overpotentials, and supercapacitors for energy storage with high capacitance. The versatility of this technique in formation of multifunctional wood hybrids can inspire both research and industrial interest in the development of wood-derived graphene materials and their nanodevices.Laser-induced porous graphene (LIG) is formed on wood by laser irradiation. This LIG is engineered into energy storage devices and electrocatalysis electrodes. The LIG from pine (P-LIG) is coated with polyaniline to form supercapacitors and with metals Co, Ni, and Fe to form electrocatalysts. The electrocatalysis of water using metal-coated P-LIG produces H2 and O2.
      PubDate: 2017-07-24T07:05:48.847195-05:
      DOI: 10.1002/adma.201702211
       
  • High Efficiency Nonfullerene Polymer Solar Cells with Thick Active Layer
           and Large Area
    • Authors: Bing Guo; Wanbin Li, Xia Guo, Xiangyi Meng, Wei Ma, Maojie Zhang, Yongfang Li
      Abstract: In this work, high-efficiency nonfullerene polymer solar cells (PSCs) are developed based on a thiazolothiazole-containing wide bandgap polymer PTZ1 as donor and a planar IDT-based narrow bandgap small molecule with four side chains (IDIC) as acceptor. Through thermal annealing treatment, a power conversion efficiency (PCE) of up to 11.5% with an open circuit voltage (Voc) of 0.92 V, a short-circuit current density (Jsc) of 16.4 mA cm−2, and a fill factor of 76.2% is achieved. Furthermore, the PSCs based on PTZ1:IDIC still exhibit a relatively high PCE of 9.6% with the active layer thickness of 210 nm and a superior PCE of 10.5% with the device area of up to 0.81 cm2. These results indicate that PTZ1 is a promising polymer donor material for highly efficient fullerene-free PSCs and large-scale devices fabrication.The nonfullerene polymer solar cells based on a wide bandgap polymer PTZ1 and a narrow bandgap acceptor IDIC exhibit weak active layer thickness and area dependence with the optimal power conversion efficiency of 11.5%, indicating that the blend of PTZ1/IDIC is potential for the practical application of polymer solar cells.
      PubDate: 2017-07-24T01:32:37.645834-05:
      DOI: 10.1002/adma.201702291
       
  • Isoindigo-Based Polymers with Small Effective Masses for High-Mobility
           Ambipolar Field-Effect Transistors
    • Authors: Jie Yang; Zhiyuan Zhao, Hua Geng, Changli Cheng, Jinyang Chen, Yunlong Sun, Longxian Shi, Yuanping Yi, Zhigang Shuai, Yunlong Guo, Shuai Wang, Yunqi Liu
      Abstract: So far, most of the reported high-mobility conjugated polymers are p-type semiconductors. By contrast, the advances in high-mobility ambipolar polymers fall greatly behind those of p-type counterparts. Instead of unipolar p-type and n-type materials, ambipolar polymers, especially balanced ambipolar polymers, are potentially serviceable for easy-fabrication and low-cost complementary metal-oxide-semiconductor circuits. Therefore, it is a critical issue to develop high-mobility ambipolar polymers. Here, three isoindigo-based polymers, PIID-2FBT, P1FIID-2FBT, and P2FIID-2FBT are developed for high-performance ambipolar organic field-effect transistors. After the incorporation of fluorine atoms, the polymers exhibit enhanced coplanarity, lower energy levels, higher crystallinity, and thus increased µe. P2FIID-2FBT exhibits n-type dominant performance with a µe of 9.70 cm2 V−1 s−1. Moreover, P1FIID-2FBT exhibits a highly balanced µh and µe of 6.41 and 6.76 cm2 V−1 s−1, respectively, which are among the highest values for balanced ambipolar polymers. Moreover, a concept “effective mass” is introduced to further study the reasons for the high performance of the polymers. All the polymers have small effective masses, indicating good intramolecular charge transport. The results demonstrate that high-mobility ambipolar semiconductors can be obtained by designing polymers with fine-tuned energy levels, small effective masses, and high crystallinity.Three isoindigo-based polymers, PIID-2FBT, P1FIID-2FBT, and P2FIID-2FBT are developed for high-performance ambipolar organic field-effect transistor. After the incorporation of fluorine atoms, the polymers show that an obvious mobility changes from p-channel dominant to n-channel dominant transport characteristics. Especially, P1FIID-2FBT exhibits a highly balanced electron/hole mobility, resulting from the fine-tuned energy levels, high crystallinity, and relatively small effective mass.
      PubDate: 2017-07-24T01:31:58.635284-05:
      DOI: 10.1002/adma.201702115
       
  • Nitrogen-Superdoped 3D Graphene Networks for High-Performance
           Supercapacitors
    • Authors: Weili Zhang; Chuan Xu, Chaoqun Ma, Guoxian Li, Yuzuo Wang, Kaiyu Zhang, Feng Li, Chang Liu, Hui-Ming Cheng, Youwei Du, Nujiang Tang, Wencai Ren
      Abstract: An N-superdoped 3D graphene network structure with an N-doping level up to 15.8 at% for high-performance supercapacitor is designed and synthesized, in which the graphene foam with high conductivity acts as skeleton and nested with N-superdoped reduced graphene oxide arogels. This material shows a highly conductive interconnected 3D porous structure (3.33 S cm−1), large surface area (583 m2 g−1), low internal resistance (0.4 Ω), good wettability, and a great number of active sites. Because of the multiple synergistic effects of these features, the supercapacitors based on this material show a remarkably excellent electrochemical behavior with a high specific capacitance (of up to 380, 332, and 245 F g−1 in alkaline, acidic, and neutral electrolytes measured in three-electrode configuration, respectively, 297 F g−1 in alkaline electrolytes measured in two-electrode configuration), good rate capability, excellent cycling stability (93.5% retention after 4600 cycles), and low internal resistance (0.4 Ω), resulting in high power density with proper high energy density.An N-superdoped 3D graphene network structure is synthesized to achieve highly conductive interconnected 3D porous structure and high N-doping level simultaneously. The supercapacitors based on this material show a remarkably high capacity, good rate capability, and excellent cycling stability.
      PubDate: 2017-07-24T01:31:25.932433-05:
      DOI: 10.1002/adma.201701677
       
  • Extremely Low Density and Super-Compressible Graphene Cellular Materials
    • Authors: Ling Qiu; Bing Huang, Zijun He, Yuanyuan Wang, Zhiming Tian, Jefferson Zhe Liu, Kun Wang, Jingchao Song, Thomas R. Gengenbach, Dan Li
      Abstract: Development of extremely low density graphene elastomer (GE) holds the potential to enable new properties that traditional cellular materials cannot offer, which are promising for a range of emerging applications, ranging from flexible electronics to multifunctional scaffolds. However, existing graphene foams with extremely low density are generally found to have very poor mechanical resilience. It is scientifically intriguing but remains unresolved whether and how the density limit of this class of cellular materials can be further pushed down while their mechanical resilience is being retained. In this work, a simple annealing strategy is developed to investigate the role of intersheet interactions in the formation of extreme-low-density of graphene-based cellular materials. It is discovered that the density limit of mechanically resilient cellular GEs can be further pushed down as low as 0.16 mg cm−3 through thermal annealing. The resultant extremely low density GEs reveal a range of unprecedented properties, including complete recovery from 98% compression in both of liquid and air, ultrahigh solvent adsorption capacity, ultrahigh pressure sensitivity, and light transmittance.Graphene cellular elastomers with a density as low as 0.16 mg cm−3 , super-compressability, ultrahigh solvent adsorption capacity, ultrahigh pressure sensitivity, and light transmittance can be fabricated by engineering the intersheet interactions of hierarchically structured graphene cellular materials.
      PubDate: 2017-07-21T06:17:11.683869-05:
      DOI: 10.1002/adma.201701553
       
  • Scaffold-Free Liver-On-A-Chip with Multiscale Organotypic Cultures
    • Authors: Yu-Shih Weng; Shau-Feng Chang, Ming-Cheng Shih, Shih-Heng Tseng, Chih-Huang Lai
      Abstract: The considerable advances that have been made in the development of organotypic cultures have failed to overcome the challenges of expressing tissue-specific functions and complexities, especially for organs that require multitasking and complex biological processes, such as the liver. Primary liver cells are ideal biological building blocks for functional organotypic reconstruction, but are limited by their rapid loss of physiological integrity in vitro. Here the concept of lattice growth used in material science is applied to develop a tissue incubator, which provides physiological cues and controls the 3D assembly of primary cells. The cues include a biological growing template, spatial coculture, biomimetic radial flow, and circulation in a scaffold-free condition. The feasibility of recapitulating a multiscale physiological structural hierarchy, complex drug clearance, and zonal physiology from the cell to tissue level in long-term cultured liver-on-a-chip is demonstrated. These methods are promising for future applications in pharmacodynamics and personal medicine.The concept of lattice growth is applied to develop a scaffold-free tissue incubator which provides physiological cues and controls the 3D assembly of primary cells. The feasibility of recapitulating a multiscale physiological structural hierarchy, complex drug clearance, and zonal physiology from the cell to tissue level in long-term cultured liver-on-a-chip is also demonstrated. These methods are promising for future applications in pharmacodynamics and personal medicine.
      PubDate: 2017-07-21T06:16:40.744131-05:
      DOI: 10.1002/adma.201701545
       
  • High-Yield Synthesis of Crystal-Phase-Heterostructured 4H/fcc Au@Pd
           Core–Shell Nanorods for Electrocatalytic Ethanol Oxidation
    • Authors: Ye Chen; Zhanxi Fan, Zhimin Luo, Xiaozhi Liu, Zhuangchai Lai, Bing Li, Yun Zong, Lin Gu, Hua Zhang
      Abstract: Noble-metal nanomaterials are attracting increasing research interest due to their promising applications in electrochemical catalysis, for example. Although great efforts have been devoted to the size-, shape-, and architecture-controlled synthesis of noble-metal nanomaterials, their crystal-phase-controlled synthesis is still in its infancy. Here, for the first time, this study reports high-yield synthesis of Au nanorods (NRs) with alternating 4H/face-centered cubic (fcc) crystal-phase heterostructures via a one-pot wet-chemical method. The coexistence of 4H and fcc phases is relatively stable, and the 4H/fcc Au NRs can serve as templates for crystal-phase-controlled epitaxial growth of other metals. As an example, bimetallic 4H/fcc Au@Pd core–shell NRs are synthesized via the epitaxial growth of Pd on 4H/fcc Au NRs. Significantly, the 4H/fcc Au@Pd NRs show superior mass activity toward the ethanol oxidation reaction, i.e., 6.2 and 4.9 times those of commercial Pd black and Pt/C catalysts, respectively. It is believed that this new synthetic strategy can be used to prepare other novel catalysts for various promising applications.High-yield crystal-phase-heterostructured 4H/fcc Au@Pd core–shell nanorods are successfully synthesized via a one-pot, facile, wet-chemical method. By using the 4H/fcc Au nanorod as a template, a 4H/fcc Au@Pd nanorod with epitaxially grown Pd shell is prepared, which exhibits superior electrocatalytic performance toward the ethanol oxidation reaction.
      PubDate: 2017-07-21T06:15:50.70393-05:0
      DOI: 10.1002/adma.201701331
       
  • Explosives in the Cage: Metal–Organic Frameworks for High-Energy
           Materials Sensing and Desensitization
    • Authors: Shan Wang; Qianyou Wang, Xiao Feng, Bo Wang, Li Yang
      Abstract: An overview of the current status of coordination polymers and metal–organic frameworks (MOFs) pertaining to the field of energetic materials is provided. The explosive applications of MOFs are discussed from two aspects: one for detection of explosives, and the other for explosive desensitization. By virtue of their adjustable pore/cage sizes, high surface area, tunable functional sites, and rich host–guest chemistry, MOFs have emerged as promising candidates for both explosive sensing and desensitization. The challenges and perspectives in these two areas are thoroughly discussed, and the processing methods for practical applications are also discussed briefly.Metal–organic frameworks (MOFs) are promising candidates for explosive sensing and desensitization due to their atomically designable and predicable structure, permanent porosity, controllable host–guest interactions, tunable inner-surface environment, and diversity of organic/metal building units. The recent developments, challenges, and perspectives in the strategies for explosive sensing and desensitization by MOFs are comprehensively discussed.
      PubDate: 2017-07-21T06:11:15.212743-05:
      DOI: 10.1002/adma.201701898
       
  • Polarized Light-Emitting Diodes Based on Patterned MoS2 Nanosheet Hole
           Transport Layer
    • Authors: Gyu Jin Choi; Quyet Van Le, Kyoung Soon Choi, Ki Chang Kwon, Ho Won Jang, Jin Seog Gwag, Soo Young Kim
      Abstract: Here, this study successfully fabricates few-layer MoS2 nanosheets from (NH4)2MoS4 and applies them as the hole transport layer as well as the template for highly polarized organic light-emitting diodes (OLEDs). The obtained material consists of polycrystalline MoS2 nanosheets with thicknesses of 2 nm. The MoS2 nanosheets are patterned by rubbing/ion-beam treatment. The Raman spectra shows that {poly(9,9-dioctylfluorene-alt-benzothiadiazole), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)]} (F8BT) on patterned MoS2 exhibits distinctive polarization behavior. It is discovered that patterned MoS2 not only improves the device efficiency but also changes the polarization behavior of the devices owing to the alignment of F8BT. This work demonstrates a highly efficient polarized OLED with a polarization ratio of 62.5:1 in the emission spectrum (166.7:1 at the peak intensity of 540 nm), which meets the manufacturing requirement. In addition, the use of patterned MoS2 nanosheets not only tunes the polarization of the OLEDs but also dramatically improves the device performance as compared with that of devices using untreated MoS2.Patterned MoS2 nanosheets obtained by rubbing/ion-beam treatment (RI-MoS2) can efficiently function as hole transport layers and templates for alignment of an emissive layer {poly(9,9-dioctylfluorene-alt-benzothiadiazole), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT)} with a nematic liquid crystal phase toward highly efficient polarized organic light-emitting diodes. Interestingly, the RI-MoS2-based device exhibits an unprecedented average polarization ratio of 62.5:1 at the emitted wavelengths (166.7:1 at the peak intensity of 540 nm).
      PubDate: 2017-07-21T06:06:59.896973-05:
      DOI: 10.1002/adma.201702598
       
  • Super-Strong, Super-Stiff Macrofibers with Aligned, Long Bacterial
           Cellulose Nanofibers
    • Authors: Sha Wang; Feng Jiang, Xu Xu, Yudi Kuang, Kun Fu, Emily Hitz, Liangbing Hu
      Abstract: With their impressive properties such as remarkable unit tensile strength, modulus, and resistance to heat, flame, and chemical agents that normally degrade conventional macrofibers, high-performance macrofibers are now widely used in various fields including aerospace, biomedical, civil engineering, construction, protective apparel, geotextile, and electronic areas. Those macrofibers with a diameter of tens to hundreds of micrometers are typically derived from polymers, gel spun fibers, modified carbon fibers, carbon-nanotube fibers, ceramic fibers, and synthetic vitreous fibers. Cellulose nanofibers are promising building blocks for future high-performance biomaterials and textiles due to their high ultimate strength and stiffness resulting from a highly ordered orientation along the fiber axis. For the first time, an effective fabrication method is successfully applied for high-performance macrofibers involving a wet-drawing and wet-twisting process of ultralong bacterial cellulose nanofibers. The resulting bacterial cellulose macrofibers yield record high tensile strength (826 MPa) and Young's modulus (65.7 GPa) owing to the large length and the alignment of nanofibers along fiber axis. When normalized by weight, the specific tensile strength of the macrofiber is as high as 598 MPa g−1 cm3, which is even substantially stronger than the novel lightweight steel (227 MPa g−1 cm3).High-performance bacterial cellulose macrofibers with outstanding mechanical properties are fabricated via a novel, facile, and green method. In addition to the remarkably high tensile strength and specific Young's modulus, the excellent dyeability, flexibility, and well-aligned structure make the all-cellulose macrofiber a novel material in the fields of functional textile, biomedicine, and nanofluidics.
      PubDate: 2017-07-21T06:06:20.512891-05:
      DOI: 10.1002/adma.201702498
       
  • Dithiopheneindenofluorene (TIF) Semiconducting Polymers with Very High
           Mobility in Field-Effect Transistors
    • Authors: Hu Chen; Michael Hurhangee, Mark Nikolka, Weimin Zhang, Mindaugas Kirkus, Marios Neophytou, Samuel J. Cryer, David Harkin, Pascal Hayoz, Mojtaba Abdi-Jalebi, Christopher R. McNeill, Henning Sirringhaus, Iain McCulloch
      Abstract: The charge-carrier mobility of organic semiconducting polymers is known to be enhanced when the energetic disorder of the polymer is minimized. Fused, planar aromatic ring structures contribute to reducing the polymer conformational disorder, as demonstrated by polymers containing the indacenodithiophene (IDT) repeat unit, which have both a low Urbach energy and a high mobility in thin-film-transistor (TFT) devices. Expanding on this design motif, copolymers containing the dithiopheneindenofluorene repeat unit are synthesized, which extends the fused aromatic structure with two additional phenyl rings, further rigidifying the polymer backbone. A range of copolymers are prepared and their electrical properties and thin-film morphology evaluated, with the co-benzothiadiazole polymer having a twofold increase in hole mobility when compared to the IDT analog, reaching values of almost 3 cm2 V−1 s−1 in bottom-gate top-contact organic field-effect transistors.A novel bridged donor (TIF) with a large planar aromatic core is designed and synthesized using a novel intramolecular CH activation strategy. This TIF unit is copolymerized with BT, FBT, DFBT, and TT repeat units, with the TIF-BT copolymer exhibiting a higher p-type mobility (2.8 cm2 V−1 s−1) compared to previously reported IDT-BT and IDTT-BT copolymers using the same device-fabrication method.
      PubDate: 2017-07-21T06:05:45.275858-05:
      DOI: 10.1002/adma.201702523
       
  • Ferroelectrics as Smart Mechanical Materials
    • Authors: Kumara Cordero-Edwards; Neus Domingo, Amir Abdollahi, Jordi Sort, Gustau Catalan
      Abstract: The mechanical properties of materials are insensitive to space inversion, even when they are crystallographically asymmetric. In practice, this means that turning a piezoelectric crystal upside down or switching the polarization of a ferroelectric should not change its mechanical response. Strain gradients, however, introduce an additional source of asymmetry that has mechanical consequences. Using nanoindentation and contact-resonance force microscopy, this study demonstrates that the mechanical response to indentation of a uniaxial ferroelectric (LiNbO3) does change when its polarity is switched, and use this mechanical asymmetry both to quantify its flexoelectricity and to mechanically read the sign of its ferroelectric domains.Ferroelectrics are smart functional materials. Their polarization responds to external stimuli (stress, voltage, and temperature) for transductors and can be switched for memories. Here, we show that, thanks to flexoelectricity, their mechanical response to indentation is also switchable, so that they may be regarded as mechanically smart. A practical consequence, demonstrated here, is the mechanical reading of ferroelectric polarity.
      PubDate: 2017-07-21T02:00:00.182605-05:
      DOI: 10.1002/adma.201702210
       
  • Contents: (Adv. Mater. 28/2017)
    • PubDate: 2017-07-21T01:46:59.393685-05:
      DOI: 10.1002/adma.201770203
       
  • Microfibers: Bioinspired Composite Microfibers for Skin Adhesion and
           Signal Amplification of Wearable Sensors (Adv. Mater. 28/2017)
    • Authors: Dirk-M. Drotlef; Morteza Amjadi, Muhammad Yunusa, Metin Sitti
      Abstract: In article number 1701353, Metin Sitti and co-workers develop bioinspired skin-adhesives composed of microfibrills decorated with conformal and mushroom-shaped tips for strong attachment to dry and wet skin. A high skin-adhesion strength of 18 kPa, along with highly enhanced signal-to-noise quality of integrated wearable strain sensors are achieved by excellent shape adaptation and microfibrillar design of skin-adhesive films.
      PubDate: 2017-07-21T01:46:59.116167-05:
      DOI: 10.1002/adma.201770207
       
  • High Performance Graphene/Ni2P Hybrid Anodes for Lithium and Sodium
           Storage through 3D Yolk–Shell-Like Nanostructural Design
    • Authors: Chao Wu; Peter Kopold, Peter A. van Aken, Joachim Maier, Yan Yu
      PubDate: 2017-07-21T01:46:58.030598-05:
      DOI: 10.1002/adma.201702795
       
  • Ultrahigh Carrier Mobility Achieved in Photoresponsive Hybrid Perovskite
           Films via Coupling with Single-Walled Carbon Nanotubes
    • Authors: Feng Li; Tom Wu
      PubDate: 2017-07-21T01:46:57.435329-05:
      DOI: 10.1002/adma.201702794
       
  • Biomaterials: Self-Adjusting, Polymeric Multilayered Roll that can Keep
           the Shapes of the Blood Vessel Scaffolds during Biodegradation (Adv.
           Mater. 28/2017)
    • Authors: Shiyu Cheng; Yu Jin, Nuoxin Wang, Feng Cao, Wei Zhang, Wei Bai, Wenfu Zheng, Xingyu Jiang
      Abstract: A self-adjusting, blood vessel-mimicking, multilayered tubular structure with two polymers, which can keep the shape of the scaffold during biodegradation, is described in article number 1700171 by Wei Bai, Wenfu Zheng, Xingyu Jiang, and co-workers. The inner layer of the tube can expand whereas the outer layers shrink to maintain the stability of the shape and the inner space of the tubular shape. This approach is useful for making scaffolds that require the maintenance of a defined shape, based on FDA-approved materials.
      PubDate: 2017-07-21T01:46:54.339754-05:
      DOI: 10.1002/adma.201770206
       
  • Masthead: (Adv. Mater. 28/2017)
    • PubDate: 2017-07-21T01:46:52.851812-05:
      DOI: 10.1002/adma.201770204
       
  • Nanomedicine: Enhancing Photodynamic Therapy through Resonance Energy
           Transfer Constructed Near-Infrared Photosensitized Nanoparticles (Adv.
           Mater. 28/2017)
    • Authors: Ling Huang; Zhanjun Li, Yang Zhao, Jinyi Yang, Yucheng Yang, Aarushi Iris Pendharkar, Yuanwei Zhang, Sharon Kelmar, Liyong Chen, Wenting Wu, Jianzhang Zhao, Gang Han
      Abstract: In article number 1604789, Gang Han and co-workers utilize a resonance energy transfer mechanism to develop a novel dyad photosensitizer which dramatically boosts NIR photon utility and shows superb tumor-targeted photodynamic therapeutic (PDT) effects with an exceptionally low-power NIR LED. This study offers a new method for designing NIR-absorbing PDT drugs for clinical cancer treatments.
      PubDate: 2017-07-21T01:46:50.469786-05:
      DOI: 10.1002/adma.201770208
       
  • Nanofilms: Biphasic Supramolecular Self-Assembly of Ferric Ions and Tannic
           Acid across Interfaces for Nanofilm Formation (Adv. Mater. 28/2017)
    • Authors: Beom Jin Kim; Sol Han, Kyung-Bok Lee, Insung S. Choi
      Abstract: Nanofilm formation of supramolecular ferric ion (FeIII)-tannic acid (TA) complexes across interfaces is reported by Insung S. Choi and co-workers in article number 1700784. FeIII (red sphere) in one phase makes a contact with TA (blue drop) in the other phase and rapidly forms the FeIII-TA film (violet layer) at the interface of the two immiscible phases.
      PubDate: 2017-07-21T01:46:50.419929-05:
      DOI: 10.1002/adma.201770201
       
  • Gas Purification: Ultrahigh and Selective SO2 Uptake in Inorganic
           Anion-Pillared Hybrid Porous Materials (Adv. Mater. 28/2017)
    • Authors: Xili Cui; Qiwei Yang, Lifeng Yang, Rajamani Krishna, Zhiguo Zhang, Zongbi Bao, Hui Wu, Qilong Ren, Wei Zhou, Banglin Chen, Huabin Xing
      Abstract: Selective recognition and dense packing of SO2 clusters is achieved through multiple synergistic host-guest/guest-guest interactions within SiF62- anion-pillared hybrid porous materials in article number 1606929, by Qiwei Yang, Banglin Chen, Huabin Xing, and co-workers. The binding sites of anions and aromatic rings on the pore surface grasp every atom of SO2 via Sδ+⋯Fδ– and Oδ–⋯Hδ+ interactions, while the interactions between SO2 molecules further promote the gas trapping.
      PubDate: 2017-07-21T01:46:49.281605-05:
      DOI: 10.1002/adma.201770205
       
  • Electrocatalysis: Hierarchical Co(OH)F Superstructure Built by
           Low-Dimensional Substructures for Electrocatalytic Water Oxidation (Adv.
           Mater. 28/2017)
    • Authors: Shanhong Wan; Jing Qi, Wei Zhang, Weina Wang, Shaokang Zhang, Kaiqiang Liu, Haoquan Zheng, Junliang Sun, Shuangyin Wang, Rui Cao
      Abstract: A novel superstructure of Co(OH)F has been developed for efficient electrocatalytic water oxidation, as described in article number 1700286, by Wei Zhang, Rui Cao, and co-workers. The as-prepared 3D Co(OH)F microsphere superstructures are built using 2D nanoflake building blocks, which are further woven by 1D nanorod foundations. The hierarchical structure of this Co(OH)F material combines the merits of all material dimensions in heterogeneous catalysis.
      PubDate: 2017-07-21T01:46:47.582693-05:
      DOI: 10.1002/adma.201770202
       
  • Probing Anisotropic Thermal Conductivity of Transition Metal
           Dichalcogenides MX2 (M = Mo, W and X = S, Se) using Time-Domain
           Thermoreflectance
    • Authors: Puqing Jiang; Xin Qian, Xiaokun Gu, Ronggui Yang
      Abstract: Transition metal dichalcogenides (TMDs) are a group of layered 2D semiconductors that have shown many intriguing electrical and optical properties. However, the thermal transport properties in TMDs are not well understood due to the challenges in characterizing anisotropic thermal conductivity. Here, a variable-spot-size time-domain thermoreflectance approach is developed to simultaneously measure both the in-plane and the through-plane thermal conductivity of four kinds of layered TMDs (MoS2, WS2, MoSe2, and WSe2) over a wide temperature range, 80–300 K. Interestingly, it is found that both the through-plane thermal conductivity and the Al/TMD interface conductance depend on the modulation frequency of the pump beam for all these four compounds. The frequency-dependent thermal properties are attributed to the nonequilibrium thermal resistance between the different groups of phonons in the substrate. A two-channel thermal model is used to analyze the nonequilibrium phonon transport and to derive the intrinsic thermal conductivity at the thermal equilibrium limit. The measurements of the thermal conductivities of bulk TMDs serve as an important benchmark for understanding the thermal conductivity of single- and few-layer TMDs.Anisotropic thermal conductivities of layered 2D crystals (MoS2, MoSe2, WS2, and WSe2) are measured using a variable-spot-size time-domain thermoreflectance approach at 80–300 K. Nonequilibrium thermal transport between the high-frequency and the low-frequency phonons is observed in the measurement results, and a two-temperature model is used to extract the intrinsic thermal-conductivity values (at the equilibrium limit).
      PubDate: 2017-07-20T04:05:40.679247-05:
      DOI: 10.1002/adma.201701068
       
  • N-Type Organic Thermoelectrics: Improved Power Factor by Tailoring
           Host–Dopant Miscibility
    • Authors: Jian Liu; Li Qiu, Giuseppe Portale, Marten Koopmans, Gert ten Brink, Jan C. Hummelen, L. Jan Anton Koster
      Abstract: In this contribution, for the first time, the polarity of fullerene derivatives is tailored to enhance the miscibility between the host and dopant molecules. A fullerene derivative with a hydrophilic triethylene glycol type side chain (PTEG-1) is used as the host and (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine n-DMBI) as the dopant. Thereby, the doping efficiency can be greatly improved to around 18% (
      PubDate: 2017-07-19T06:47:10.35965-05:0
      DOI: 10.1002/adma.201701641
       
  • Preventing Thin Film Dewetting via Graphene Capping
    • Authors: Peigen Cao; Peter Bai, Arash A. Omrani, Yihan Xiao, Kacey L. Meaker, Hsin-Zon Tsai, Aiming Yan, Han Sae Jung, Ramin Khajeh, Griffin F. Rodgers, Youngkyou Kim, Andrew S. Aikawa, Mattew A. Kolaczkowski, Yi Liu, Alex Zettl, Ke Xu, Michael F. Crommie, Ting Xu
      Abstract: A monolayer 2D capping layer with high Young's modulus is shown to be able to effectively suppress the dewetting of underlying thin films of small organic semiconductor molecule, polymer, and polycrystalline metal, respectively. To verify the universality of this capping layer approach, the dewetting experiments are performed for single-layer graphene transferred onto polystyrene (PS), semiconducting thienoazacoronene (EH-TAC), gold, and also MoS2 on PS. Thermodynamic modeling indicates that the exceptionally high Young's modulus and surface conformity of 2D capping layers such as graphene and MoS2 substantially suppress surface fluctuations and thus dewetting. As long as the uncovered area is smaller than the fluctuation wavelength of the thin film in a dewetting process via spinodal decomposition, the dewetting should be suppressed. The 2D monolayer-capping approach opens up exciting new possibilities to enhance the thermal stability and expands the processing parameters for thin film materials without significantly altering their physical properties.A monolayer 2D capping layer is shown to be able to effectively suppress the dewetting of thin films of both polymer and polycrystalline metal. Thermodynamic modeling indicates that the exceptionally high Young's modulus and surface conformity of 2D capping layers such as graphene and MoS2 substantially suppress surface fluctuations and thus dewetting.
      PubDate: 2017-07-19T06:40:42.385202-05:
      DOI: 10.1002/adma.201701536
       
  • Erythrocyte-Membrane-Enveloped Perfluorocarbon as Nanoscale Artificial Red
           Blood Cells to Relieve Tumor Hypoxia and Enhance Cancer Radiotherapy
    • Authors: Min Gao; Chao Liang, Xuejiao Song, Qian Chen, Qiutong Jin, Chao Wang, Zhuang Liu
      Abstract: Hypoxia, a common feature within many types of solid tumors, is known to be closely associated with limited efficacy for cancer therapies, including radiotherapy (RT) in which oxygen is essential to promote radiation-induced cell damage. Here, an artificial nanoscale red-blood-cell system is designed by encapsulating perfluorocarbon (PFC), a commonly used artificial blood substitute, within biocompatible poly(d,l-lactide-co-glycolide) (PLGA), obtaining PFC@PLGA nanoparticles, which are further coated with a red-blood-cell membrane (RBCM). The developed PFC@PLGA-RBCM nanoparticles with the PFC core show rather efficient loading of oxygen, as well as greatly prolonged blood circulation time owing to the coating of RBCM. With significantly improved extravascular diffusion within the tumor mass, owing to their much smaller nanoscale sizes compared to native RBCs with micrometer sizes, PFC@PLGA-RBCM nanoparticles are able to effectively deliver oxygen into tumors after intravenous injection, leading to greatly relieved tumor hypoxia and thus remarkably enhanced treatment efficacy during RT. This work thus presents a unique type of nanoscale RBC mimic for efficient oxygen delivery into solid tumors, favorable for cancer treatment by RT, and potentially other types of therapy as well.Artificial nanoscale red blood cells (RBCs) are fabricated by coating perfluorocarbon-loaded nanoparticles with an RBC membrane. Upon intravenous injection, such nanoparticles, with efficient oxygen-loading function, prolonged blood-circulation time, and great extravascular diffusion ability, are able to effectively deliver oxygen into tumors, leading to greatly relieved tumor hypoxia and thus remarkably enhanced treatment efficacy during radiotherapy.
      PubDate: 2017-07-19T01:42:22.051608-05:
      DOI: 10.1002/adma.201701429
       
  • Direct Synthesis of Large-Area 2D Mo2C on In Situ Grown Graphene
    • Authors: Dechao Geng; Xiaoxu Zhao, Zhongxin Chen, Weiwei Sun, Wei Fu, Jianyi Chen, Wei Liu, Wu Zhou, Kian Ping Loh
      Abstract: As a new member of the MXene group, 2D Mo2C has attracted considerable interest due to its potential application as electrodes for energy storage and catalysis. The large-area synthesis of Mo2C film is needed for such applications. Here, the one-step direct synthesis of 2D Mo2C-on-graphene film by molten copper-catalyzed chemical vapor deposition (CVD) is reported. High-quality and uniform Mo2C film in the centimeter range can be grown on graphene using a Mo–Cu alloy catalyst. Within the vertical heterostructure, graphene acts as a diffusion barrier to the phase-segregated Mo and allows nanometer-thin Mo2C to be grown. Graphene-templated growth of Mo2C produces well-faceted, large-sized single crystals with low defect density, as confirmed by scanning transmission electron microscopy (STEM) measurements. Due to its more efficient graphene-mediated charge-transfer kinetics, the as-grown Mo2C-on-graphene heterostructure shows a much lower onset voltage for hydrogen evolution reactions as compared to Mo2C-only electrodes.The one-step direct synthesis of a 2D Mo2C-on-graphene heterostructure by molten Cu-catalyzed chemical vapor deposition is reported. Graphene acts as a diffusion barrier to phase-segregated Mo, thus allowing the thickness of Mo2C to be kinetically controlled. The heterostructure functions as a highly stable electrode in hydrogen evolution reactions.
      PubDate: 2017-07-19T01:41:54.78962-05:0
      DOI: 10.1002/adma.201700072
       
  • 3D Anisotropic Thermal Conductivity of Exfoliated Rhenium Disulfide
    • Authors: Hyejin Jang; Christopher R. Ryder, Joshua D. Wood, Mark C. Hersam, David G. Cahill
      Abstract: ReS2 represents a different class of 2D materials, which is characterized by low symmetry having 1D metallic chains within the planes and extremely weak interlayer bonding. Here, the thermal conductivity of single-crystalline ReS2 in a distorted 1T phase is determined at room temperature for the in-plane directions parallel and perpendicular to the Re-chains, and the through-plane direction using time-domain thermoreflectance. ReS2 is prepared in the form of flakes having thicknesses of 60–450 nm by micromechanical exfoliation, and their crystalline orientations are identified by polarized Raman spectroscopy. The in-plane thermal conductivity is higher along the Re-chains, (70 ± 18) W m−1 K−1, as compared to transverse to the chains, (50 ± 13) W m−1 K−1. As expected from the weak interlayer bonding, the through-plane thermal conductivity is the lowest observed to date for 2D materials, (0.55 ± 0.07) W m−1 K−1, resulting in a remarkably high anisotropy of (130 ± 40) and (90 ± 30) for the two in-plane directions. The thermal conductivity and interface thermal conductance of ReS2 are discussed relative to the other 2D materials.The 3D thermal-conductivity tensor of ReS2, a transition-metal dichalcogenide with Re-chains on the plane, is determined using time-domain thermoreflectance. The thermal conductivity is higher along the Re-chains, 70 W m−1 K−1, compared to transverse to the chains, 50 W m−1 K−1. The through-plane thermal conductivity is the lowest observed for 2D materials, 0.55 W m−1 K−1.
      PubDate: 2017-07-19T01:40:33.221698-05:
      DOI: 10.1002/adma.201700650
       
  • Precise and Arbitrary Deposition of Biomolecules onto Biomimetic Fibrous
           Matrices for Spatially Controlled Cell Distribution and Functions
    • Authors: Chao Jia; Bowen Luo, Haoyu Wang, Yongqian Bian, Xueyong Li, Shaohua Li, Hongjun Wang
      Abstract: Advances in nano-/microfabrication allow the fabrication of biomimetic substrates for various biomedical applications. In particular, it would be beneficial to control the distribution of cells and relevant biomolecules on an extracellular matrix (ECM)-like substrate with arbitrary micropatterns. In this regard, the possibilities of patterning biomolecules and cells on nanofibrous matrices are explored here by combining inkjet printing and electrospinning. Upon investigation of key parameters for patterning accuracy and reproducibility, three independent studies are performed to demonstrate the potential of this platform for: i) transforming growth factor (TGF)-β1-induced spatial differentiation of fibroblasts, ii) spatiotemporal interactions between breast cancer cells and stromal cells, and iii) cancer-regulated angiogenesis. The results show that TGF-β1 induces local fibroblast-to-myofibroblast differentiation in a dose-dependent fashion, and breast cancer clusters recruit activated stromal cells and guide the sprouting of endothelial cells in a spatially resolved manner. The established platform not only provides strategies to fabricate ECM-like interfaces for medical devices, but also offers the capability of spatially controlling cell organization for fundamental studies, and for high-throughput screening of various biomolecules for stem cell differentiation and cancer therapeutics.With the demonstration of biomolecule deposition (single or multiple types) onto biomimetic extracellular matrix–like nanofibrous matrices with arbitrary shape, pattern, and dosage using an inkjet-printing-based technology, a cost-effective and high-throughput platform is presented for controllably organizing various cells for cell–cell and cell–matrix interactions or potentially screening various biomolecules for stem cell differentiation and therapeutics for cancer therapy.
      PubDate: 2017-07-19T01:37:02.178749-05:
      DOI: 10.1002/adma.201701154
       
  • Engineering Single Nanopores on Gold Nanoplates by Tuning Crystal Screw
           Dislocation
    • Authors: Yueming Zhai; Fan Zhang, Bo Zhang, Xiaohu Gao
      Abstract: Compared with the large variety of solid gold nanostructures, synthetic approaches for their hollow counterparts are limited, largely confined to chemical and irradiation-based etching of preformed nanostructures. In particular, the preparation of through nanopore structures is extremely challenging. Here, a unique strategy for direct synthesis of gold nanopores in solution without the need for sacrificial templates or postsynthesis processing is reported. By controlling the degree of crystal screw dislocation, a single through pore with diameter ranging from sub-nanometer to tens of nanometers, in the center of large gold nanoplates, can be engineered with precision. Ionic current rectification behaviors are observed using the gold nanopore, potentially enabling new capabilities in biosensing, sequencing, and imaging.High-throughput production of solid-state nanopores is a major challenge. A novel methodology is reported for solution-phase synthesis of Au nanoplates with a single through pore with diameters ranging from sub-nanometers to tens of nanometers in the center, based on crystal screw dislocation.
      PubDate: 2017-07-19T01:36:11.764447-05:
      DOI: 10.1002/adma.201703102
       
  • Mesoporous Silica Thin Membranes with Large Vertical Mesochannels for
           Nanosize-Based Separation
    • Authors: Yupu Liu; Dengke Shen, Gang Chen, Ahmed A. Elzatahry, Manas Pal, Hongwei Zhu, Longlong Wu, Jianjian Lin, Daifallah Al-Dahyan, Wei Li, Dongyuan Zhao
      Abstract: Membrane separation technologies are of great interest in industrial processes such as water purification, gas separation, and materials synthesis. However, commercial filtration membranes have broad pore size distributions, leading to poor size cutoff properties. In this work, mesoporous silica thin membranes with uniform and large vertical mesochannels are synthesized via a simple biphase stratification growth method, which possess an intact structure over centimeter size, ultrathin thickness (≤50 nm), high surface areas (up to 1420 m2 g−1), and tunable pore sizes from ≈2.8 to 11.8 nm by adjusting the micelle parameters. The nanofilter devices based on the free-standing mesoporous silica thin membranes show excellent performances in separating differently sized gold nanoparticles (>91.8%) and proteins (>93.1%) due to the uniform pore channels. This work paves a promising way to develop new membranes with well-defined pore diameters for highly efficient nanosize-based separation at the macroscale.A biphase stratification growth strategy is developed for fabrication of the well-ordered mesoporous silica thin membranes with large vertical and tunable mesochannels on a variety of substrates. Profiting by centimeter-scale size, tunable, and well-defined vertical mesochannels, the obtained nanofilters based on free-standing mesoporous silica membranes show excellent size-selective separation power for gold nanoparticles mixtures, ovalbumin, and cytochrome c proteins.
      PubDate: 2017-07-18T02:47:02.629589-05:
      DOI: 10.1002/adma.201702274
       
  • High-Temperature Ionic Epitaxy of Halide Perovskite Thin Film and the
           Hidden Carrier Dynamics
    • Authors: Yiping Wang; Xin Sun, Zhizhong Chen, Yi-Yang Sun, Shengbai Zhang, Toh-Ming Lu, Esther Wertz, Jian Shi
      Abstract: High-temperature vapor phase epitaxy (VPE) has been proved ubiquitously powerful in enabling high-performance electro-optic devices in III–V semiconductor field. A typical example is the successful growth of p-type GaN by VPE for blue light-emitting diodes. VPE excels as it controls film defects such as point/interface defects and grain boundary, thanks to its high-temperature processing condition and controllable deposition rate. For the first time, single-crystalline high-temperature VPE halide perovskite thin film has been demonstrated—a unique platform on unveiling previously uncovered carrier dynamics in inorganic halide perovskites. Toward wafer-scale epitaxial and grain boundary-free film is grown with alkali halides as substrates. It is shown the metal alkali halides could be used as universal substrates for VPE growth of perovskite due to their similar material chemistry and lattice constant. With VPE, hot photoluminescence and nanosecond photo-Dember effect are revealed in inorganic halide perovskite. These two phenomena suggest that inorganic halide perovskite could be as compelling as its organic–inorganic counterpart regarding optoelectronic properties and help explain the long carrier lifetime in halide perovskite. The findings suggest a new avenue on developing high-quality large-scale single-crystalline halide perovskite films requiring precise control of defects and morphology.It is shown that alkali halides can be used as a universal substrate for the vapor phase epitaxy of halide perovskites. With vapor phase epitaxy, hot photoluminescence and nanosecond photo-Dember effect are revealed in an inorganic halide perovskite, suggesting it could be as compelling as its organic–inorganic counterpart for developing high-performance optoelectronics.
      PubDate: 2017-07-18T02:46:11.408491-05:
      DOI: 10.1002/adma.201702643
       
  • Engineering the Surface of Smart Nanocarriers Using a
           pH-/Thermal-/GSH-Responsive Polymer Zipper for Precise Tumor Targeting
           Therapy In Vivo
    • Authors: Penghui Zhang; Yan Wang, Jing Lian, Qi Shen, Chen Wang, Bohan Ma, Yuchao Zhang, Tingting Xu, Jianxin Li, Yongping Shao, Feng Xu, Jun-Jie Zhu
      Abstract: Nanocarrier surface chemistry plays a vital role in mediating cell internalization and enhancing delivery efficiency during in vivo chemotherapy. Inspired by the ability of proteins to alter their conformation to mediate functions, a pH-/thermal-/glutathione-responsive polymer zipper consisting of cell-penetrating poly(disulfide)s and thermosensitive polymers bearing guanidinium/phosphate (Gu+/pY−) motifs to spatiotemporally tune the surface composition of nanocarriers for precise tumor targeting and efficient drug delivery is developed. Surface engineering allows the nanocarriers to remain undetected during blood circulation and favors passive accumulation at tumor sites, where the acidic microenvironment and photothermal heating break the pY−/Gu+ binding and rupture the zipper, thereby exposing the penetrating shell and causing enhanced cellular uptake via counterion-/thiol-/receptor-mediated endocytosis. The in vivo study demonstrates that by manipulating the surface states on command, the nanocarriers show longer blood circulation time, minimized uptake and drug leakage in normal organs, and enhanced accumulation and efficient drug release at tumor sites, greatly inhibiting tumor growth with only slight damage to normal tissues. If integrated with a photothermal dye approved by the U.S. Food and Drug Administration (FDA), polymer zipper would provide a versatile protocol for engineering nanomedicines with high selectivity and efficiency for clinical cancer treatment.pH-/thermal-/glutathione-responsive polymer zippers are screened and explored to tune nanocarrier surface compositions on command for precise tumor targeting in vivo. The nanocarriers remain stealthy during blood circulation, but their surfaces are activated by the acidic microenvironment and photothermal heating at tumor sites for enhanced cellular uptake and efficient drug release, presenting a versatile engineering strategy for nanomedicinal use.
      PubDate: 2017-07-18T02:41:59.883386-05:
      DOI: 10.1002/adma.201702311
       
  • In Situ Two-Step Photoreduced SERS Materials for On-Chip Single-Molecule
           Spectroscopy with High Reproducibility
    • Authors: Wenjie Yan; Longkun Yang, Jianing Chen, Yaqi Wu, Peijie Wang, Zhipeng Li
      Abstract: A method is developed to synthesize surface-enhanced Raman scattering (SERS) materials capable of single-molecule detection, integrated with a microfluidic system. Using a focused laser, silver nanoparticle aggregates as SERS monitors are fabricated in a microfluidic channel through photochemical reduction. After washing out the monitor, the aggregates are irradiated again by the same laser. This key step leads to full reduction of the residual reactants, which generates numerous small silver nanoparticles on the former nanoaggregates. Consequently, the enhancement ability of the SERS monitor is greatly boosted due to the emergence of new “hot spots.” At the same time, the influence of the notorious “memory effect” in microfluidics is substantially suppressed due to the depletion of surface residues. Taking these advantages, two-step photoreduced SERS materials are able to detect different types of molecules with the concentration down to 10−13m. Based on a well-accepted bianalyte approach, it is proved that the detection limit reaches the single-molecule level. From a practical point of view, the detection reproducibility at different probing concentrations is also investigated. It is found that the effective single-molecule SERS measurements can be raised up to ≈50%. This microfluidic SERS with high reproducibility and ultrasensitivity will find promising applications in on-chip single-molecule spectroscopy.On-chip single-molecule surface-enhanced Raman scattering (SERS) monitors free of the “memory effect” are fabricated in microfluidics by the two-step photoreduction method. Proved by bianalyte statistics, on-chip single-molecule detection is accomplished. This is a quick and well-reproducible microfluidic SERS technique with the detection limit as low as 10−13m. At the single-molecule level, the detection reproducibility can reach up to 50%.
      PubDate: 2017-07-18T02:40:46.980172-05:
      DOI: 10.1002/adma.201702893
       
  • Recent Progress in the Preparation, Assembly, Transformation, and
           Applications of Layer-Structured Nanodisks beyond Graphene
    • Authors: Xiao Zhang; Hongfei Cheng, Hua Zhang
      Abstract: Layered nanodisks with confined thickness and lateral size have been emerging as a unique type of two-dimensional (2D) nanomaterials in recent years. Inheriting some properties of 2D nanosheets and meanwhile possessing the size-confinement effect, these layered nanodisks exhibit unique optical, electronic, and chemical properties, which endow them with great promise in a wide range of applications. Here, the recent progress of layered nanodisks is introduced. The synthetic strategies, assembly, structural/compositional transformation, and applications of layered nanodisks are systematically described and discussed, with emphasis on their new appealing structures and functions. Finally, some perspectives and future research directions of this promising field are given.Layered nanodisks with confined thickness and lateral size are emerging as a unique type of 2D nanomaterial. The recent progress in layered nanodisks, including synthetic strategies, assembly, structural/compositional transformation, and applications are discussed.
      PubDate: 2017-07-17T08:14:50.255642-05:
      DOI: 10.1002/adma.201701704
       
  • Photostriction of CH3NH3PbBr3 Perovskite Crystals
    • Authors: Tzu-Chiao Wei; Hsin-Ping Wang, Ting-You Li, Chun-Ho Lin, Ying-Hui Hsieh, Ying-Hao Chu, Jr-Hau He
      Abstract: Organic–inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light–matter interactions. The photoinduced strain of CH3NH3PbBr3 is investigated using high-resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH3NH3PbBr3 is calculated as 2.08 × 10−8 m2 W−1 at room temperature under visible light illumination. The significant photostriction of CH3NH3PbBr3 is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation–rotation coupling. Unlike CH3NH3PbI3, it is noted that the photostriction of CH3NH3PbBr3 is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH3NH3PbBr3 for applications in next-generation optical micro-electromechanical devices.The photoinduced strain of CH3NH3PbBr3 is investigated using high-resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations. The significant photostriction of CH3NH3PbBr3 can be attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation–rotation coupling.
      PubDate: 2017-07-17T08:13:54.538174-05:
      DOI: 10.1002/adma.201701789
       
  • Strongly Enhanced Photovoltaic Performance and Defect Physics of
           Air-Stable Bismuth Oxyiodide (BiOI)
    • Authors: Robert L. Z. Hoye; Lana C. Lee, Rachel C. Kurchin, Tahmida N. Huq, Kelvin H. L. Zhang, Melany Sponseller, Lea Nienhaus, Riley E. Brandt, Joel Jean, James Alexander Polizzotti, Ahmed Kursumović, Moungi G. Bawendi, Vladimir Bulović, Vladan Stevanović, Tonio Buonassisi, Judith L. MacManus-Driscoll
      Abstract: Bismuth-based compounds have recently gained increasing attention as potentially nontoxic and defect-tolerant solar absorbers. However, many of the new materials recently investigated show limited photovoltaic performance. Herein, one such compound is explored in detail through theory and experiment: bismuth oxyiodide (BiOI). BiOI thin films are grown by chemical vapor transport and found to maintain the same tetragonal phase in ambient air for at least 197 d. The computations suggest BiOI to be tolerant to antisite and vacancy defects. All-inorganic solar cells (ITO NiOx BiOI ZnO Al) with negligible hysteresis and up to 80% external quantum efficiency under select monochromatic excitation are demonstrated. The short-circuit current densities and power conversion efficiencies under AM 1.5G illumination are nearly double those of previously reported BiOI solar cells, as well as other bismuth halide and chalcohalide photovoltaics recently explored by many groups. Through a detailed loss analysis using optical characterization, photoemission spectroscopy, and device modeling, direction for future improvements in efficiency is provided. This work demonstrates that BiOI, previously considered to be a poor photocatalyst, is promising for photovoltaics.Bismuth oxyiodide (BiOI) is demonstrated to be defect-tolerant, with the bulk phase unchanged after 197 d in ambient air. In solar cells, up to 80% external quantum efficiency is achieved. The short-circuit current densities and power conversion efficiencies are nearly double previous reports of photovoltaics based on BiOI, as well as other recently-explored bismuth halides and chalcohalides.
      PubDate: 2017-07-17T08:13:41.819583-05:
      DOI: 10.1002/adma.201702176
       
  • Encoding Random Hot Spots of a Volume Gold Nanorod Assembly for Ultralow
           Energy Memory
    • Authors: Qiaofeng Dai; Min Ouyang, Weiguang Yuan, Jinxiang Li, Banghong Guo, Sheng Lan, Songhao Liu, Qiming Zhang, Guang Lu, Shaolong Tie, Haidong Deng, Yi Xu, Min Gu
      Abstract: Data storage with ultrahigh density, ultralow energy, high security, and long lifetime is highly desirable in the 21st century and optical data storage is considered as the most promising way to meet the challenge of storing big data. Plasmonic coupling in regularly arranged metallic nanoparticles has demonstrated its superior properties in various applications due to the generation of hot spots. Here, the discovery of the polarization and spectrum sensitivity of random hot spots generated in a volume gold nanorod assembly is reported. It is demonstrated that the two-photon-induced absorption and two-photon-induced luminescence of the gold nanorods adjacent to such hot spots are enhanced significantly because of plasmonic coupling. The polarization, wavelength, and spatial multiplexing of the hot spots can be realized by using an ultralow energy of only a few picojoule per pulse, which is two orders of magnitude lower than the value in the state-of-the-art technology that utilizes isolated gold nanorods. The ultralow recording energy reduces the cross-talk between different recording channels and makes it possible to realize rewriting function, improving significantly both the quality and capacity of optical data storage. It is anticipated that the demonstrated technology can facilitate the development of multidimensional optical data storage for a greener future.The random hot spots created in a volume gold nanorod assembly are found to be polarization and spectrum sensitive and the encoding of such hot spots can be utilized for multidimensional optical data storage with an ultrahigh density of ≈13.8 Tbit cm−3 and ultralow energy of only a few picojoule per pulse.
      PubDate: 2017-07-17T02:43:45.293587-05:
      DOI: 10.1002/adma.201701918
       
  • Self-Powered Real-Time Arterial Pulse Monitoring Using Ultrathin Epidermal
           Piezoelectric Sensors
    • Authors: Dae Yong Park; Daniel J. Joe, Dong Hyun Kim, Hyewon Park, Jae Hyun Han, Chang Kyu Jeong, Hyelim Park, Jung Gyu Park, Boyoung Joung, Keon Jae Lee
      Abstract: Continuous monitoring of an arterial pulse using a pressure sensor attached on the epidermis is an important technology for detecting the early onset of cardiovascular disease and assessing personal health status. Conventional pulse sensors have the capability of detecting human biosignals, but have significant drawbacks of power consumption issues that limit sustainable operation of wearable medical devices. Here, a self-powered piezoelectric pulse sensor is demonstrated to enable in vivo measurement of radial/carotid pulse signals in near-surface arteries. The inorganic piezoelectric sensor on an ultrathin plastic achieves conformal contact with the complex texture of the rugged skin, which allows to respond to the tiny pulse changes arising on the surface of epidermis. Experimental studies provide characteristics of the sensor with a sensitivity (≈0.018 kPa−1), response time (≈60 ms), and good mechanical stability. Wireless transmission of detected arterial pressure signals to a smart phone demonstrates the possibility of self-powered and real-time pulse monitoring system.A self-powered, flexible, and piezoelectric pressure sensor for real-time arterial pulse monitoring is demonstrated on ultrathin substrates via an inorganic-based laser lift-off process. The ultrathin self-powered sensor with good sensitivity of 0.018 kPa−1 adheres to human epidermis and successfully detects arterial pulse and respiration. Finally, pulse signals are wirelessly transmitted to a smart phone for realizing wearable healthcare sensors.
      PubDate: 2017-07-17T02:42:26.922274-05:
      DOI: 10.1002/adma.201702308
       
  • Disordered Conformation with Low Pii Helix in Phosphoproteins Orchestrates
           Biomimetic Apatite Formation
    • Authors: Melika Sarem; Steffen Lüdeke, Ralf Thomann, Pavel Salavei, Zhaoyong Zou, Wouter Habraken, Admir Masic, V. Prasad Shastri
      Abstract: The interplay between noncollagenous proteins and biomineralization is widely accepted, yet the contribution of their secondary structure in mineral formation remains to be clarified. This study demonstrates a role for phosvitin, an intrinsically disordered phosphoprotein, in chick embryo skeletal development, and using circular dichroism and matrix least-squares Henderson–Hasselbalch global fitting, unravels three distinct pH-dependent secondary structures in phosvitin. By sequestering phosvitin on a biomimetic 3D insoluble cationic framework at defined pHs, access is gained to phosvitin in various conformational states. Induction of biomimetic mineralization at near physiological conditions reveals that a disordered secondary structure with a low content of PII helix is remarkably efficient at promoting calcium adsorption, and results in the formation of biomimetic hydroxyapatite through an amorphous calcium phosphate precursor. By extending this finding to phosphorylated full-length human recombinant dentin matrix protein-1 (17-513 AA), this bioinspired approach provides compelling evidence for the role of a disordered secondary structure in phosphoproteins in bone-like apatite formation.Biomineralization is the process by which mineral phase is deposited in living systems in the presence of protein mediators. Avian and mammalian phosphoproteins with a low-PII-helix-containing disordered secondary structure are more efficient at binding calcium complexes and mediating formation of bone-like hydroxyapatite (HAp) in comparison to a β-sheet-dominated secondary structure. The formation of this biomimetic HAp occurs via amorphous nanosphere precursors.
      PubDate: 2017-07-17T02:23:32.499198-05:
      DOI: 10.1002/adma.201701629
       
  • Photothermal Ring Integrated Intraocular Lens for High-Efficient Eye
           Disease Treatment
    • Authors: Yao-Xin Lin; Xue-Feng Hu, Yang Zhao, Yu-Juan Gao, Chao Yang, Sheng-Lin Qiao, Yi Wang, Pei-Pei Yang, Jiao Yan, Xin-Ce Sui, Zeng-Ying Qiao, Li-Li Li, Jiang-Bing Xie, Si-Quan Zhu, Xiao-Chun Wu, Yongsheng Li, Lei Wang, Hao Wang
      Abstract: Posterior capsule opacification (PCO) is the most common complication after cataract surgery. So far, the only method for PCO treatment is the precisely focused laser surgery. However, it causes severe complications such as physical damages and neuron impairments. Here, a nanostructured photothermal ring integrated intraocular lens (Nano-IOLs) is reported, in which the rim of commercially available IOLs (C-IOLs) is decorated with silica coated Au nanorods (Au@SiO2), for high-efficient prevention of PCO after cataract surgery. The Nano-IOLs is capable of eliminating the residual lens epithelial cells (LECs) around Nano-IOLs under mild laser treatment and block the formation of disordered LECs fibrosis, which eventually leads to the loss of vision. The Nano-IOLs shows good biocompatibility as well as extraordinary region-confined photothermal effect. In vivo studies reveal that PCO occurrence in rabbit models is about 30%–40% by using Nano-IOLs, which is significantly lower than the control group that treated with C-IOLs (100% PCO occurrence) 30 d postsurgery. To the best of our knowledge, it is the first example to integrate nanotechnology with intraocular implants aiming to clinically relevant PCO. Our findings indicate that spatial controllability of photothermal effect from nanomaterials may provide a unique way to intervene the PCO-induced loss of vision.Here, an intraocular lens with Au@SiO2 nanorod-modified rim (Nano-IOLs) is reported. Compared to the commercially available IOLs, Nano-IOLs retains the intrinsic biocompatibility and optical properties and meanwhile exhibits extraordinary region-confined photothermal effect. In vitro and rabbit experimental results confirm that Nano-IOLs can effectively kill LECs nearby the rim and effectively prevent the occurrence of posterior capsule opacification.
      PubDate: 2017-07-17T02:22:42.70912-05:0
      DOI: 10.1002/adma.201701617
       
  • Poly(Vinylpyrollidone)- and Selenocysteine-Modified Bi2Se3 Nanoparticles
           Enhance Radiotherapy Efficacy in Tumors and Promote Radioprotection in
           Normal Tissues
    • Authors: Jiangfeng Du; Zhanjun Gu, Liang Yan, Yuan Yong, Xuan Yi, Xiao Zhang, Jing Liu, Renfei Wu, Cuicui Ge, Chunying Chen, Yuliang Zhao
      Abstract: The development of a new generation of nanoscaled radiosensitizers that can not only enhance radiosensitization of tumor tissues, but also increase radioresistance of healthy tissue is highly desirable, but remains a great challenge. Here, this paper reports a new versatile theranostics based on poly(vinylpyrollidone)- and selenocysteine-modified Bi2Se3 nanoparicles (PVP-Bi2Se3@Sec NPs) for simultaneously enhancing radiotherapeutic effects and reducing the side-effects of radiation. The as-prepared nanoparticles exhibit significantly enhanced free-radical generation upon X-ray radiation, and remarkable photothermal effects under 808 nm NIR laser irradiation because of their strong X-ray attenuation ability and high NIR absorption capability. Moreover, these PVP-Bi2Se3@Sec NPs are biodegradable. In vivo, part of selenium can be released from NPs and enter the blood circulation system, which can enhance the immune function and reduce the side-effects of radiation in the whole body. As a consequence, improved superoxide dismutase and glutathione peroxidase activities, promoted secretion of cytokines, increased number of white blood cell, and reduced marrow DNA suppression are found after radiation treatment in vivo. Moreover, there is no significant in vitro and in vivo toxicity of PVP-Bi2Se3@Sec NPs during the treatment, which demonstrates that PVP-Bi2Se3@Sec NPs have good biocompatibility.Poly(vinylpyrollidone)- and selenocysteine-modified Bi2Se3 nanoparticles are fabricated and then explored as both radiosensitizer in tumor tissue and radioresistance agents in healthy tissues for improving radiotherapy therapeutic effects and simultaneously minimizing their toxicity via enhancing the immune function as well as reducing the side-effect of radiation in the whole body.
      PubDate: 2017-07-17T02:22:10.761742-05:
      DOI: 10.1002/adma.201701268
       
  • Humidity-Responsive Single-Nanoparticle-Layer Plasmonic Films
    • Authors: Jianlei Shen; Binquan Luan, Hao Pei, Zaixing Yang, Xiaolei Zuo, Gang Liu, Jiye Shi, Lihua Wang, Ruhong Zhou, Wenlong Cheng, Chunhai Fan
      Abstract: 2D materials possess many interesting properties, and have shown great application potentials. In this work, the development of humidity-responsive, 2D plasmonic nanostructures with switchable chromogenic properties upon wetting–dewetting transitions is reported. By exploiting DNA hybridization-directed anchoring of gold nanoparticles (AuNPs) on substrates, a series of single-nanoparticle-layer (SNL) plasmonic films is fabricated. Due to the collective plasmonic responses in SNL, these ultrathin 2D films display rapid and reversible red-blue color change upon the wetting–dewetting transition, suggesting that hydration-induced microscopic plasmonic coupling between AuNPs is replicated in the macroscopic, centimeter-scale films. It is also found that hydration finely tunes the electric field distribution between AuNPs in the SNL film, based on which responsive surface-enhanced Raman scattering substrates with spatially homogeneous hot spots are developed. Thus it is expected that DNA-mediated 2D SNL structures open new avenues for designing miniaturized plasmonic nanodevices with various applications.DNA hybridization-directed anchoring of gold nanoparticles on various substrates leads to 2D single-nanoparticle-layer plasmonic films with humidity-responsive switchable chromogenic properties upon wetting–dewetting transitions.
      PubDate: 2017-07-17T02:20:39.156967-05:
      DOI: 10.1002/adma.201606796
       
  • Ternary Porous Cobalt Phosphoselenide Nanosheets: An Efficient
           Electrocatalyst for Electrocatalytic and Photoelectrochemical Water
           Splitting
    • Authors: Yang Hou; Ming Qiu, Tao Zhang, Xiaodong Zhuang, Chang-Soo Kim, Chris Yuan, Xinliang Feng
      Abstract: Exploring efficient and earth-abundant electrocatalysts is of great importance for electrocatalytic and photoelectrochemical hydrogen production. This study demonstrates a novel ternary electrocatalyst of porous cobalt phosphoselenide nanosheets prepared by a combined hydrogenation and phosphation strategy. Benefiting from the enhanced electric conductivity and large surface area, the ternary nanosheets supported on electrochemically exfoliated graphene electrodes exhibit excellent catalytic activity and durability toward hydrogen evolution in alkali, achieving current densities of 10 and 20 mA cm−2 at overpotentials of 150 and 180 mV, respectively, outperforming those reported for transition metal dichalcogenides and first-row transition metal pyrites catalysts. Theoretical calculations reveal that the synergistic effects of Se vacancies and subsequent P displacements of Se atoms around the vacancies in the resulting cobalt phosphoselenide favorably change the electronic structure of cobalt selenide, assuring a rapid charge transfer and optimal energy barrier of hydrogen desorption, and thus promoting the proton kinetics. The overall-water-splitting with 10 mA cm−2 at a low voltage of 1.64 V is achieved using the ternary electrode as both the anode and cathode, and the performance surpasses that of the Ir/C–Pt/C couple for sufficiently high overpotentials. Moreover, the integration of ternary nanosheets with macroporous silicon enables highly efficient solar-driven photoelectrochemical hydrogen production.A novel ternary electrocatalyst of porous cobalt phosphoselenide nanosheets is designed and constructed for water splitting. The synergistic effects of Se vacancies and subsequent phosphation around the vacancies in the resulting cobalt phosphoselenide favorably change the electronic structure of cobalt selenide, assuring a rapid charge transfer and optimal energy barrier of hydrogen desorption, which eventually promote proton kinetic properties.
      PubDate: 2017-07-17T02:17:16.730954-05:
      DOI: 10.1002/adma.201701589
       
  • Hierarchical VS2 Nanosheet Assemblies: A Universal Host Material for the
           Reversible Storage of Alkali Metal Ions
    • Authors: Junhua Zhou; Lu Wang, Mingye Yang, Jinghua Wu, Fengjiao Chen, Wenjing Huang, Na Han, Hualin Ye, Feipeng Zhao, Youyong Li, Yanguang Li
      Abstract: Reversible electrochemical storage of alkali metal ions is the basis of many secondary batteries. Over years, various electrode materials are developed and optimized for a specific type of alkali metal ions (Li+, Na+, or K+), yet there are very few (if not none) candidates that can serve as a universal host material for all of them. Herein, a facile solvothermal method is developed to prepare VS2 nanosheet assemblies. Individual nanosheets are featured with a few atomic layer thickness, and they are hierarchically arranged with minimized stacking. Electrochemical measurements show that VS2 nanosheet assemblies enable the rapid and durable storage of Li+, Na+, or K+ ions. Most remarkably, the large reversible specific capacity and great cycling stability observed for both Na+ and K+ are extraordinary and superior to most existing electrode materials. The experimental results of this study are further supported by density functional theory calculations showing that the layered structure of VS2 has large adsorption energy and low diffusion barriers for the intercalation of alkali metal ions.Hierarchical VS2 nanosheet assemblies featuring a few atomic-layer nanosheet thickness are prepared by a facile solvothermal method in N-methyl-2-pyrrolidone. They can serve as a universal host material for the reversible electrochemical storage of Li+, Na+, or K+ ions with large capacity, great rate capability, and satisfactory cycling stability.
      PubDate: 2017-07-17T02:16:21.85089-05:0
      DOI: 10.1002/adma.201702061
       
  • High-Performance Polymers Sandwiched with Chemical Vapor Deposited
           Hexagonal Boron Nitrides as Scalable High-Temperature Dielectric Materials
           
    • Authors: Amin Azizi; Matthew R. Gadinski, Qi Li, Mohammed Abu AlSaud, Jianjun Wang, Yi Wang, Bo Wang, Feihua Liu, Long-Qing Chen, Nasim Alem, Qing Wang
      Abstract: Polymer dielectrics are the preferred materials of choice for power electronics and pulsed power applications. However, their relatively low operating temperatures significantly limit their uses in harsh-environment energy storage devices, e.g., automobile and aerospace power systems. Herein, hexagonal boron nitride (h-BN) films are prepared from chemical vapor deposition (CVD) and readily transferred onto polyetherimide (PEI) films. Greatly improved performance in terms of discharged energy density and charge–discharge efficiency is achieved in the PEI sandwiched with CVD-grown h-BN films at elevated temperatures when compared to neat PEI films and other high-temperature polymer and nanocomposite dielectrics. Notably, the h-BN-coated PEI films are capable of operating with>90% charge–discharge efficiencies and delivering high energy densities, i.e., 1.2 J cm−3, even at a temperature close to the glass transition temperature of polymer (i.e., 217 °C) where pristine PEI almost fails. Outstanding cyclability and dielectric stability over a straight 55 000 charge–discharge cycles are demonstrated in the h-BN-coated PEI at high temperatures. The work demonstrates a general and scalable pathway to enable the high-temperature capacitive energy applications of a wide range of engineering polymers and also offers an efficient method for the synthesis and transfer of 2D nanomaterials at the scale demanded for applications.Hexagonal boron nitride films grown by chemical vapor deposition are readily transferred onto polymers, yielding sandwiched films exhibiting superior energy densities and greater efficiencies at high temperatures. This work enables the capacitive applications of engineering polymers in high-temperature electronics and energy devices, and also offers an efficient synthesis method for 2D nanomaterials at the scale demanded for applications.
      PubDate: 2017-07-17T02:15:58.83791-05:0
      DOI: 10.1002/adma.201701864
       
  • Enhancing Performance of Nonfullerene Acceptors via Side-Chain Conjugation
           Strategy
    • Authors: Jiayu Wang; Wei Wang, Xiaohui Wang, Yang Wu, Qianqian Zhang, Cenqi Yan, Wei Ma, Wei You, Xiaowei Zhan
      Abstract: A side-chain conjugation strategy in the design of nonfullerene electron acceptors is proposed, with the design and synthesis of a side-chain-conjugated acceptor (ITIC2) based on a 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]di(cyclopenta-dithiophene) electron-donating core and 1,1-dicyanomethylene-3-indanone electron-withdrawing end groups. ITIC2 with the conjugated side chains exhibits an absorption peak at 714 nm, which redshifts 12 nm relative to ITIC1. The absorption extinction coefficient of ITIC2 is 2.7 × 105m−1 cm−1, higher than that of ITIC1 (1.5 × 105m−1 cm−1). ITIC2 exhibits slightly higher highest occupied molecular orbital (HOMO) (−5.43 eV) and lowest unoccupied molecular orbital (LUMO) (−3.80 eV) energy levels relative to ITIC1 (HOMO: −5.48 eV; LUMO: −3.84 eV), and higher electron mobility (1.3 × 10−3 cm2 V−1 s−1) than that of ITIC1 (9.6 × 10−4 cm2 V−1 s−1). The power conversion efficiency of ITIC2-based organic solar cells is 11.0%, much higher than that of ITIC1-based control devices (8.54%). Our results demonstrate that side-chain conjugation can tune energy levels, enhance absorption, and electron mobility, and finally enhance photovoltaic performance of nonfullerene acceptors.A side-chain conjugation strategy in the design of nonfullerene electron acceptors is proposed and the first example of a side-chain-conjugated fused-ring electron acceptor is presented. Polymer solar cells based on side-chain-conjugated ITIC2 show a champion power conversion efficiency of 11.0%, much higher than its counterpart ITIC1-based devices (8.54%).
      PubDate: 2017-07-17T02:15:29.145555-05:
      DOI: 10.1002/adma.201702125
       
  • Rational Design of Three-Layered TiO2@Carbon@MoS2 Hierarchical Nanotubes
           for Enhanced Lithium Storage
    • Authors: Sibo Wang; Bu Yuan Guan, Le Yu, Xiong Wen (David) Lou
      Abstract: Here we demonstrate the rational design and synthesis of three-layered TiO2@carbon@MoS2 hierarchical nanotubes for anode applications in lithium-ion batteries (LIBs). Through an efficient step-by-step strategy, ultrathin MoS2 nanosheets are grown on nitrogen-doped carbon (NC) coated TiO2 nanotubes to achieve the TiO2@NC@MoS2 tubular nanostructures. This smart design can effectively shorten the diffusion length of Li+ ions, increase electric conductivity of the electrode, relax volume variation of electrode materials upon cycling, and provide more active sites for electrochemical reactions. Owing to these structural and compositional features, the hierarchical TiO2@NC@MoS2 nanotubes manifest remarkable lithium storage performance with good rate capability and long cycle life.Hierarchical TiO2@carbon@MoS2 tubular-like nanostructures are rationally synthesized via an efficient multistep route. The unique architecture and composition of this nanohybrid can effectively improve electric conductivity, promote transport kinetics of Li+ ions, and buffer volume variation upon cycling. With these benefits, the nanohybrid electrode manifests enhanced electrochemical properties as an anode material for lithium-ion batteries.
      PubDate: 2017-07-17T02:13:06.591858-05:
      DOI: 10.1002/adma.201702724
       
  • Defect Engineering of Chalcogen-Tailored Oxygen Electrocatalysts for
           Rechargeable Quasi-Solid-State Zinc–Air Batteries
    • Authors: Jing Fu; Fathy M. Hassan, Cheng Zhong, Jun Lu, Han Liu, Aiping Yu, Zhongwei Chen
      Abstract: A critical bottleneck limiting the performance of rechargeable zinc–air batteries lies in the inefficient bifunctional electrocatalysts for the oxygen reduction and evolution reactions at the air electrodes. Hybridizing transition-metal oxides with functional graphene materials has shown great advantages due to their catalytic synergism. However, both the mediocre catalytic activity of metal oxides and the restricted 2D mass/charge transfer of graphene render these hybrid catalysts inefficient. Here, an effective strategy combining anion substitution, defect engineering, and the dopant effect to address the above two critical issues is shown. This strategy is demonstrated on a hybrid catalyst consisting of sulfur-deficient cobalt oxysulfide single crystals and nitrogen-doped graphene nanomeshes (CoO0.87S0.13/GN). The defect chemistries of both oxygen-vacancy-rich, nonstoichiometric cobalt oxysulfides and edge-nitrogen-rich graphene nanomeshes lead to a remarkable improvement in electrocatalytic performance, where CoO0.87S0.13/GN exhibits strongly comparable catalytic activity to and much better stability than the best-known benchmark noble-metal catalysts. In application to quasi-solid-state zinc–air batteries, CoO0.87S0.13/GN as a freestanding catalyst assembly benefits from both structural integrity and enhanced charge transfer to achieve efficient and very stable cycling operation over 300 cycles with a low discharge–charge voltage gap of 0.77 V at 20 mA cm−2 under ambient conditions.A high-temperature ammonolysis is proven effective for improving both the mediocre catalytic activity of metal oxides and the restricted 2D mass/charge transfer of graphene. The defect chemistries of both oxygen-vacancy-rich cobalt oxysulfides and edge-nitrogen-rich graphene nanomeshes of the hybrid catalyst lead to a remarkable improvement in electrocatalytic performance for oxygen reduction and evolution reactions.
      PubDate: 2017-07-17T02:12:45.498867-05:
      DOI: 10.1002/adma.201702526
       
  • A Highly Versatile and Adaptable Artificial Leaf with Floatability and
           Planar Compact Design Applicable in Various Natural Environments
    • Authors: Sangkuk Kim; Taewan Kim, Seunghyup Lee, Seunghyeon Baek, Taiho Park, Kijung Yong
      Abstract: As a promising means of solar energy conversion, photovoltaic (PV) cell-based electrolysis has recently drawn considerable attention for its effective solar fuel generation; especially the generation of hydrogen by solar water splitting. Inspired by remarkable accomplishments in enhancing the solar-to-hydrogen conversion efficiency, various efforts have aimed at fostering convenient and practical uses of PV electrolysis to make this technology ubiquitous, manageable, and efficient. Here, the design and function of a monolithic photoelectrolysis system—a so-called artificial leaf—for use in various environments are highlighted. The uniquely designed artificial-leaf system facilitates an unbiased water-splitting reaction by combining superstrate PV cells in series with single-face electrodes in a compact 2D catalytic configuration. Floatability is a new feature of the water-splitting artificial leaf; this feature maximizes solar light utilization and allows for easy retrieval for recycling. Additionally, its planar design enables operation of the device in water-scarce conditions. These characteristics endow the artificial leaf with versatility and a high adaptability to natural environments, widening the applicability of the device.A highly versatile and adaptable artificial leaf with floatability and planar compact design applicable in various natural environments is developed. Floatability is a new feature of the water-splitting artificial leaf; this feature maximizes solar light utilization and allows for easy retrieval for recycling. Additionally, its planar design enables operation of the device in water-scarce conditions.
      PubDate: 2017-07-17T02:12:18.277662-05:
      DOI: 10.1002/adma.201702431
       
  • Ultra-High Pyridinic N-Doped Porous Carbon Monolith Enabling High-Capacity
           K-Ion Battery Anodes for Both Half-Cell and Full-Cell Applications
    • Authors: Yihao Xie; Yu Chen, Lei Liu, Peng Tao, Mouping Fan, Na Xu, Xiaowei Shen, Chenglin Yan
      Abstract: An ultrahigh pyridinic N-content-doped porous carbon monolith is reported, and the content of pyridinic N reaches up to 10.1% in overall material (53.4 ± 0.9% out of 18.9 ± 0.4% N content), being higher than most of previously reported N-doping carbonaceous materials, which exhibit greatly improved electrochemical performance for potassium storage, especially in term of the high reversible capacity. Remarkably, the pyridinic N-doped porous carbon monolith (PNCM) electrode exhibits high initial charge capacity of 487 mAh g−1 at a current density of 20 mA g−1, which is one of the highest reversible capacities among all carbonaceous anodes for K-ion batteries. Moreover, the K-ion full cell is successfully assembled, demonstrating a high practical energy density of 153.5 Wh kg−1. These results make PNCM promising for practical application in energy storage devices and encourage more investigations on a similar potassium storage system.Ultrahigh pyridinic N-doped porous carbon monolith (PNCM) with 3D interconnected structure is fabricated by using melamine–formaldehyde resin as a hard template and a nitrogen source. The electrode delivers an extremely high reversible capacity of 487 mAh g−1 at 20 mA g−1. The K-ion full cell assembled with PNCM/3,4,9,10-perylene tetracarboxylicacid dianhydride demonstrates the promising potential for practical applications.
      PubDate: 2017-07-17T02:11:52.860358-05:
      DOI: 10.1002/adma.201702268
       
  • Biotransporting Self-Assembled Nanofactories Using Polymer Vesicles with
           Molecular Permeability for Enzyme Prodrug Cancer Therapy
    • Authors: Tomoki Nishimura; Yoshihiro Sasaki, Kazunari Akiyoshi
      Abstract: As “biotransporting nanofactories”, in vivo therapeutic biocatalyst nanoreactors would enable encapsulated enzymes to transform inert prodrugs or neutralize toxic compounds at target disease sites. This would offer outstanding potential for next-generation therapeutic platforms, such as enzyme prodrug therapy. Designing such advanced materials has, however, proven challenging. Here, it is shown that self-assembled nanofactories formulate with polymeric vesicles with an intrinsically permeable membrane. The vesicles, CAPsomes, are composed of carbohydrate-b-poly(propylene glycol) and show molecular-weight-depended permeability. This property enables CAPsomes to act as biocatalyst nanoreactors, protecting encapsulated enzymes from degradation while acting on low-molecular-weight substrates. In tumor bearing mice, combined treatment with enzyme-loaded CAPsomes and doxorubicin prodrug inhibit tumor growth in these mice without any observable toxicity. The results demonstrate, for the first time, in vivo therapeutic efficacy of CAPsomes as nanofactories for enzyme prodrug cancer therapy.Self-assembled nanofactories formulated with intrinsically molecular permeable polymer vesicles are reported. The vesicles are composed of maltooligosaccharide-b-poly(propylene glycol) and have molecular-weight-dependent permeable membrane. Because of this permeability, the vesicles serve as nanofactories that can transform prodrugs into drugs in vivo for cancer therapy.
      PubDate: 2017-07-17T02:11:19.048767-05:
      DOI: 10.1002/adma.201702406
       
  • Bifunctional Transition Metal Hydroxysulfides: Room-Temperature
           Sulfurization and Their Applications in Zn–Air Batteries
    • Authors: Hao-Fan Wang; Cheng Tang, Bin Wang, Bo-Quan Li, Qiang Zhang
      Abstract: Bifunctional electrocatalysis for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) constitutes the bottleneck of various sustainable energy devices and systems like rechargeable metal–air batteries. Emerging catalyst materials are strongly requested toward superior electrocatalytic activities and practical applications. In this study, transition metal hydroxysulfides are presented as bifunctional OER/ORR electrocatalysts for Zn–air batteries. By simply immersing Co-based hydroxide precursor into solution with high-concentration S2−, transition metal hydroxides convert to hydroxysulfides with excellent morphology preservation at room temperature. The as-obtained Co-based metal hydroxysulfides are with high intrinsic reactivity and electrical conductivity. The electron structure of the active sites is adjusted by anion modulation. The potential for 10 mA cm−2 OER current density is 1.588 V versus reversible hydrogen electrode (RHE), and the ORR half-wave potential is 0.721 V versus RHE, with a potential gap of 0.867 V for bifunctional oxygen electrocatalysis. The Co3FeS1.5(OH)6 hydroxysulfides are employed in the air electrode for a rechargeable Zn–air battery with a small overpotential of 0.86 V at 20.0 mA cm−2, a high specific capacity of 898 mAh g−1, and a long cycling life, which is much better than Pt and Ir-based electrocatalyst in Zn–air batteries.Transition metal hydroxysulfides are proposed as bifunctional electrocatalysts in working Zn–air batteries with high oxygen evolution reaction/oxygen reduction reaction reactivities, high power densities, large capacities, and extraordinary stabilities. The transition metal hydroxysulfides are fabricated through a novel room-temperature sulfurization strategy, which opens new doors to materials innovation of transition metal (hydro/oxy)sulfides and their practical applications in hetero/electrocatalysis, energy storage, and healthcare applications.
      PubDate: 2017-07-17T02:10:45.11068-05:0
      DOI: 10.1002/adma.201702327
       
  • A Swellable Microneedle Patch to Rapidly Extract Skin Interstitial Fluid
           for Timely Metabolic Analysis
    • Authors: Hao Chang; Mengjia Zheng, Xiaojun Yu, Aung Than, Razina Z. Seeni, Rongjie Kang, Jingqi Tian, Duong Phan Khanh, Linbo Liu, Peng Chen, Chenjie Xu
      Abstract: Skin interstitial fluid (ISF) is an emerging source of biomarkers for disease diagnosis and prognosis. Microneedle (MN) patch has been identified as an ideal platform to extract ISF from the skin due to its pain-free and easy-to-administrated properties. However, long sampling time is still a serious problem which impedes timely metabolic analysis. In this study, a swellable MN patch that can rapidly extract ISF is developed. The MN patch is made of methacrylated hyaluronic acid (MeHA) and further crosslinked through UV irradiation. Owing to the supreme water affinity of MeHA, this MN patch can extract sufficient ISF in a short time without the assistance of extra devices, which remarkably facilitates timely metabolic analysis. Due to covalent crosslinked network, the MN patch maintains the structure integrity in the swelling hydrated state without leaving residues in skin after usage. More importantly, the extracted ISF metabolites can be efficiently recovered from MN patch by centrifugation for the subsequent offline analysis of metabolites such as glucose and cholesterol. Given the recent trend of easy-to-use point-of-care devices for personal healthcare monitoring, this study opens a new avenue for the development of MN-based microdevices for sampling ISF and minimally invasive metabolic detection.A swellable microneedle (MN) patch is developed to rapidly extract skin interstitial fluid (ISF) for timely metabolic analysis. The MN patch can efficiently extract sufficient ISF in a few minutes and well maintain its structure. The ISF can be easily recovered by centrifugation method for subsequent offline metabolic analysis.
      PubDate: 2017-07-17T02:06:50.058422-05:
      DOI: 10.1002/adma.201702243
       
  • Selective High-Frequency Mechanical Actuation Driven by the VO2 Electronic
           Instability
    • Authors: Nicola Manca; Luca Pellegrino, Teruo Kanki, Warner J. Venstra, Giordano Mattoni, Yoshiyuki Higuchi, Hidekazu Tanaka, Andrea D. Caviglia, Daniele Marré
      Abstract: Relaxation oscillators consist of periodic variations of a physical quantity triggered by a static excitation. They are a typical consequence of nonlinear dynamics and can be observed in a variety of systems. VO2 is a correlated oxide with a solid-state phase transition above room temperature, where both electrical resistance and lattice parameters undergo a drastic change in a narrow temperature range. This strong nonlinear response allows to realize spontaneous electrical oscillations in the megahertz range under a DC voltage bias. These electrical oscillations are employed to set into mechanical resonance a microstructure without the need of any active electronics, with small power consumption and with the possibility to selectively excite specific flexural modes by tuning the value of the DC electrical bias in a range of few hundreds of millivolts. This actuation method is robust and flexible and can be implemented in a variety of autonomous DC-powered devices.High-frequency mechanical actuation of a microelectromechanical system (MEMS) device from a DC electrical bias is achieved by employing VO2, a material exhibiting a combined electrical and structural phase transition at 65 °C. The DC bias triggers spontaneous and repetitive phase transitions on a micrometric region that works as engine to power the movement of the MEMS around its mechanical resonances.
      PubDate: 2017-07-17T02:05:46.555134-05:
      DOI: 10.1002/adma.201701618
       
  • An All-Solution-Based Hybrid CMOS-Like Quantum Dot/Carbon Nanotube
           Inverter
    • Authors: Artem G. Shulga; Vladimir Derenskyi, Jorge Mario Salazar-Rios, Dmitry N. Dirin, Martin Fritsch, Maksym V. Kovalenko, Ullrich Scherf, Maria A. Loi
      Abstract: The development of low-cost, flexible electronic devices is subordinated to the advancement in solution-based and low-temperature-processable semiconducting materials, such as colloidal quantum dots (QDs) and single-walled carbon nanotubes (SWCNTs). Here, excellent compatibility of QDs and SWCNTs as a complementary pair of semiconducting materials for fabrication of high-performance complementary metal-oxide-semiconductor (CMOS)-like inverters is demonstrated. The n-type field effect transistors (FETs) based on I− capped PbS QDs (Vth = 0.2 V, on/off = 105, SS-th = 114 mV dec−1, µe = 0.22 cm2 V−1 s−1) and the p-type FETs with tailored parameters based on low-density random network of SWCNTs (Vth = −0.2 V, on/off> 105, SS-th = 63 mV dec−1, µh = 0.04 cm2 V−1 s−1) are integrated on the same substrate in order to obtain high-performance hybrid inverters. The inverters operate in the sub-1 V range (0.9 V) and have high gain (76 V/V), large maximum-equal-criteria noise margins (80%), and peak power consumption of 3 nW, in combination with low hysteresis (10 mV).An all-solution-processable hybrid CMOS-like inverter based on PbS quantum dots (n-type) and single-walled carbon nanotubes (p-type) is demonstrated. The inverter operates in the sub-1 V range (0.9 V) and have high gain (76 V/V), large noise margins (80%), low hysteresis (10 mV), and low peak power consumption (3 nW).
      PubDate: 2017-07-17T02:01:52.447435-05:
      DOI: 10.1002/adma.201701764
       
  • Wet-Spun Superelastic Graphene Aerogel Millispheres with Group Effect
    • Authors: Xiaoli Zhao; Weiquan Yao, Weiwei Gao, Hao Chen, Chao Gao
      Abstract: Graphene aerogel has attracted great attention due to its unique properties, such as ultralow density, superelasticity, and high specific surface area. It shows huge potential in energy devices, high-performance pressure sensors, contaminates adsorbents, and electromagnetic wave absorbing materials. However, there still remain some challenges to further promote the development and real application of graphene aerogel including cost-effective scalable fabrication and miniaturization with group effect. This study shows millimeter-scale superelastic graphene aerogel spheres (GSs) with group effect and multifunctionality. The GSs are continuously fabricated on a large scale by wet spinning of graphene oxide liquid crystals followed by facile drying and thermal annealing. Such GS has an unusual core–shell structure with excellent elasticity and specific strength. Significantly, both horizontally and vertically grouped spheres exhibit superelasticity comparable to individual spheres, enabling it to fully recover at 95% strain, and even after 1000 compressive cycles at 70% strain, paving the way to wide applications such as pressure-elastic and adsorbing materials. The GS shows a press-fly behavior with an extremely high jump velocity up to 1.2 m s−1. For the first time, both free and oil-adsorbed GSs are remotely manipulated on water by electrostatic charge due to their ultralow density and hydrophobic properties.Superelastic graphene aerogel spheres (GSs) with core–shell structure are continuously produced via wet-spinning method, demonstrating unique group effect and multifunctionality. Grouped spheres exhibit superelasticity comparable to individual spheres, enabling them to fully recover at 95% strain, even after 1000 compressive cycles at 70% strain. For the first time, both free and oil-soaked GSs are remotely manipulated on water by electrostatic charge.
      PubDate: 2017-07-17T02:01:04.909366-05:
      DOI: 10.1002/adma.201701482
       
  • Dopant-Free Hole-Transporting Materials for Stable and Efficient
           Perovskite Solar Cells
    • Authors: Sanghyun Paek; Peng Qin, Yonghui Lee, Kyung Taek Cho, Peng Gao, Giulia Grancini, Emad Oveisi, Paul Gratia, Kasparas Rakstys, Shaheen A. Al-Muhtaseb, Christian Ludwig, Jaejung Ko, Mohammad Khaja Nazeeruddin
      Abstract: Molecularly engineered novel dopant-free hole-transporting materials for perovskite solar cells (PSCs) combined with mixed-perovskite (FAPbI3)0.85(MAPbBr3)0.15 (MA: CH3NH3+, FA: NH=CHNH3+) that exhibit an excellent power conversion efficiency of 18.9% under AM 1.5 conditions are investigated. The mobilities of FA-CN, and TPA-CN are determined to be 1.2 × 10−4 cm2 V−1 s−1 and 1.1 × 10−4 cm2 V−1 s−1, respectively. Exceptional stability up to 500 h is measured with the PSC based on FA-CN. Additionally, it is found that the maximum power output collected after 1300 h remained 65% of its initial value. This opens up new avenue for efficient and stable PSCs exploring new materials as alternatives to Spiro-OMeTAD.Novel dopant-free hole-transporting materials for perovskite solar cells (PSCs), which exhibit an excellent power conversion efficiency of 18.9% under AM 1.5 conditions are investigated. The PSC based on FA-CN shows exceptional stability up to 500 h. The PCE collected during 1300 h is observed to remain at 65% of its initial value. This opens an avenue for efficient and stable PSCs exploring new materials.
      PubDate: 2017-07-17T01:59:45.420498-05:
      DOI: 10.1002/adma.201606555
       
  • Visible-Light-Excited Ultralong Organic Phosphorescence by Manipulating
           Intermolecular Interactions
    • Authors: Suzhi Cai; Huifang Shi, Jiewei Li, Long Gu, Yun Ni, Zhichao Cheng, Shan Wang, Wei-wei Xiong, Lin Li, Zhongfu An, Wei Huang
      Abstract: Visible light is much more available and less harmful than ultraviolet light, but ultralong organic phosphorescence (UOP) with visible-light excitation remains a formidable challenge. Here, a concise chemical approach is provided to obtain bright UOP by tuning the molecular packing in the solid state under irradiation of available visible light, e.g., a cell phone flashlight under ambient conditions (room temperature and in air). The excitation spectra exhibit an obvious redshift via the incorporation of halogen atoms to tune intermolecular interactions. UOP is achieved through H-aggregation to stabilize the excited triplet state, with a high phosphorescence efficiency of 8.3% and a considerably long lifetime of 0.84 s. Within a brightness of 0.32 mcd m−2 that can be recognized by the naked eye, UOP can last for 104 s in total. Given these features, ultralong organic phosphorescent materials are used to successfully realize dual data encryption and decryption. Moreover, well-dispersed UOP nanoparticles are prepared by polymer-matrix encapsulation in an aqueous solution, and their applications in bioimaging are tentatively being studied. This result will pave the way toward expanding metal-free organic phosphorescent materials and their applications.Visible-light-excited ultralong organic phosphorescence is achieved with a considerably long phosphorescence lifetime of 0.84 s and high quantum efficiency of 8.3%. Given these features, visible-light-excited ultralong organic phosphorescent materials can be successfully applied in dual data encryption and molecular bioimaging.
      PubDate: 2017-07-17T01:59:12.47145-05:0
      DOI: 10.1002/adma.201701244
       
  • Intrinsic 3D Prestressing: A New Route for Increasing Strength and
           Improving Toughness of Hybrid Inorganic Biocements
    • Authors: Martha Schamel; Jake E. Barralet, Michael Gelinsky, Jürgen Groll, Uwe Gbureck
      Abstract: Cement is the most consumed resource and is the most widely used material globally. The ability to extrinsically prestress cementitious materials with tendons usually made from steel allows the creation of high-strength bridges and floors from this otherwise brittle material. Here, a dual setting cement system based on the combination of hydraulic cement powder with an aqueous silk fibroin solution that intrinsically generates a 3D prestressing during setting, dramatically toughening the cement to the point it can be cut with scissors, is reported. Changes of both ionic concentration and pH during cement setting are shown to create an interpenetrating silk fibroin inorganic composite with the combined properties of the elastic polymer and the rigid cement. These hybrid cements are self-densifying and show typical ductile fracture behavior when dry and a high elasticity under wet conditions with mechanical properties (bending and compressive strength) nearly an order of magnitude higher than the fibroin-free cement reference.A silk fibroin modified cement system is reported which intrinsically generates an isotropic prestressing during setting. These hybrid cements are self-densifying and show typical ductile fracture behavior when dry and a high elasticity under wet conditions with mechanical properties nearly an order of magnitude higher than the fibroin-free cement reference.
      PubDate: 2017-07-17T01:58:25.479932-05:
      DOI: 10.1002/adma.201701035
       
  • Enhancing Photodynamic Therapy through Resonance Energy Transfer
           Constructed Near-Infrared Photosensitized Nanoparticles
    • Authors: Ling Huang; Zhanjun Li, Yang Zhao, Jinyi Yang, Yucheng Yang, Aarushi Iris Pendharkar, Yuanwei Zhang, Sharon Kelmar, Liyong Chen, Wenting Wu, Jianzhang Zhao, Gang Han
      Abstract: Photodynamic therapy (PDT) is an important cancer treatment modality due to its minimally invasive nature. However, the efficiency of existing PDT drug molecules in the deep-tissue-penetrable near-infrared (NIR) region has been the major hurdle that has hindered further development and clinical usage of PDT. Thus, herein a strategy is presented to utilize a resonance energy transfer (RET) mechanism to construct a novel dyad photosensitizer which is able to dramatically boost NIR photon utility and enhance singlet oxygen generation. In this work, the energy donor moiety (distyryl-BODIPY) is connected to a photosensitizer (i.e., diiodo-distyryl-BODIPY) to form a dyad molecule (RET-BDP). The resulting RET-BDP shows significantly enhanced absorption and singlet oxygen efficiency relative to that of the acceptor moiety of the photosensitizer alone in the NIR range. After being encapsulated with biodegradable copolymer pluronic F-127-folic acid (F-127-FA), RET-BDP molecules can form uniform and small organic nanoparticles that are water soluble and tumor targetable. Used in conjunction with an exceptionally low-power NIR LED light irradiation (10 mW cm−2), these nanoparticles show superior tumor-targeted therapeutic PDT effects against cancer cells both in vitro and in vivo relative to unmodified photosensitizers. This study offers a new method to expand the options for designing NIR-absorbing photosensitizers for future clinical cancer treatments.Resonance energy transfer constructed NIR-absorbing BODIPY-based photosensitized dyad nanoparticles are developed. These nanoparticles enable targeted photodynamic therapy upon application of low-power NIR LED light irradiation. This work provides a new concept for the design of biocompatible nanoparticles with significantly improved NIR sensitivity, which is key to photodynamic therapy development.
      PubDate: 2017-06-06T08:10:20.951416-05:
      DOI: 10.1002/adma.201604789
       
  • Tunable Photocontrolled Motions Using Stored Strain Energy in Malleable
           Azobenzene Liquid Crystalline Polymer Actuators
    • Authors: Xili Lu; Shengwei Guo, Xia Tong, Hesheng Xia, Yue Zhao
      Abstract: A new strategy for enhancing the photoinduced mechanical force is demonstrated using a reprocessable azobenzene-containing liquid crystalline network (LCN). The basic idea is to store mechanical strain energy in the polymer beforehand so that UV light can then be used to generate a mechanical force not only from the direct light to mechanical energy conversion upon the trans–cis photoisomerization of azobenzene mesogens but also from the light-triggered release of the prestored strain energy. It is shown that the two mechanisms can add up to result in unprecedented photoindued mechanical force. Together with the malleability of the polymer stemming from the use of dynamic covalent bonds for chain crosslinking, large-size polymer photoactuators in the form of wheels or spring-like “motors” can be constructed, and, by adjusting the amount of prestored strain energy in the polymer, a variety of robust, light-driven motions with tunable rolling or moving direction and speed can be achieved. The approach of prestoring a controllable amount of strain energy to obtain a strong and tunable photoinduced mechanical force in azobenzene LCN can be further explored for applications of light-driven polymer actuators.By prestoring mechanical strain energy in a reprocessable liquid crystal polymer network containing azobenzene mesogens, unprecedented mechanical force can be generated under UV light irradiation, which enables continuous light-driven motions of large polymer actuators in the form of wheels and spring-like “motors,” with tunable moving speed and controllable moving direction.
      PubDate: 2017-06-06T01:42:12.786892-05:
      DOI: 10.1002/adma.201606467
       
  • Bioinspired Ultrastrong Solid Electrolytes with Fast Proton Conduction
           along 2D Channels
    • Authors: Guangwei He; Mingzhao Xu, Jing Zhao, Shengtao Jiang, Shaofei Wang, Zhen Li, Xueyi He, Tong Huang, Moyuan Cao, Hong Wu, Michael D. Guiver, Zhongyi Jiang
      Abstract: Solid electrolytes have attracted much attention due to their great prospects in a number of energy- and environment-related applications including fuel cells. Fast ion transport and superior mechanical properties of solid electrolytes are both of critical significance for these devices to operate with high efficiency and long-term stability. To address a common tradeoff relationship between ionic conductivity and mechanical properties, electrolyte membranes with proton-conducting 2D channels and nacre-inspired architecture are reported. An unprecedented combination of high proton conductivity (326 mS cm−1 at 80 °C) and superior mechanical properties (tensile strength of 250 MPa) are achieved due to the integration of exceptionally continuous 2D channels and nacre-inspired brick-and-mortar architecture into one materials system. Moreover, the membrane exhibits higher power density than Nafion 212 membrane, but with a comparative weight of only ≈0.1, indicating potential savings in system weight and cost. Considering the extraordinary properties and independent tunability of ion conduction and mechanical properties, this bioinspired approach may pave the way for the design of next-generation high-performance solid electrolytes with nacre-like architecture.The advancement of solid electrolytes is severely impeded by the strong tradeoff relationship between ion-conduction and mechanical properties. Through integrating 2D channels and “brick-and-mortar” architecture into one materials system, an unprecedented combination of high proton conductivity and superior mechanical strength are achieved. This intriguing design may pave the way for the bioinspired design of next-generation high-performance solid electrolytes.
      PubDate: 2017-06-06T01:41:56.958736-05:
      DOI: 10.1002/adma.201605898
       
  • Discovery of Rapid and Reversible Water Insertion in Rare Earth Sulfates:
           A New Process for Thermochemical Heat Storage
    • Authors: Naoyuki Hatada; Kunihiko Shizume, Tetsuya Uda
      Abstract: Thermal energy storage based on chemical reactions is a prospective technology for the reduction of fossil-fuel consumption by storing and using waste heat. For widespread application, a critical challenge is to identify appropriate reversible reactions that occur below 250 °C, where abundant low-grade waste heat and solar energy might be available. Here, it is shown that lanthanum sulfate monohydrate La2(SO4)3⋅H2O undergoes rapid and reversible dehydration/hydration reactions in the temperature range from 50 to 250 °C upon heating/cooling with remarkably small thermal hysteresis (
      PubDate: 2017-06-06T01:41:24.462026-05:
      DOI: 10.1002/adma.201606569
       
  • Hierarchical Co(OH)F Superstructure Built by Low-Dimensional Substructures
           for Electrocatalytic Water Oxidation
    • Authors: Shanhong Wan; Jing Qi, Wei Zhang, Weina Wang, Shaokang Zhang, Kaiqiang Liu, Haoquan Zheng, Junliang Sun, Shuangyin Wang, Rui Cao
      Abstract: The development of new materials/structures for efficient electrocatalytic water oxidation, which is a key reaction in realizing artificial photosynthesis, is an ongoing challenge. Herein, a Co(OH)F material as a new electrocatalyst for the oxygen evolution reaction (OER) is reported. The as-prepared 3D Co(OH)F microspheres are built by 2D nanoflake building blocks, which are further woven by 1D nanorod foundations. Weaving and building the substructures (1D nanorods and 2D nanoflakes) provides high structural void porosity with sufficient interior space in the resulting 3D material. The hierarchical structure of this Co(OH)F material combines the merits of all material dimensions in heterogeneous catalysis. The anisotropic low-dimensional (1D and 2D) substructures possess the advantages of a high surface-to-volume ratio and fast charge transport. The interconnectivity of the nanorods is also beneficial for charge transport. The high-dimensional (3D) architecture results in sufficient active sites per the projected electrode surface area and is favorable for efficient mass diffusion during catalysis. A low overpotential of 313 mV is required to drive an OER current density of 10 mA cm−2 on a simple glassy carbon (GC) working electrode in a 1.0 m KOH aqueous solution.3D Co(OH)F microspheres are synthesized for highly efficient electrocatalytic water oxidation. The microspheres are built by 2D nanoflake building blocks, which are further woven by 1D nanorod foundations. The hierarchical structure of this free-standing Co(OH)F material combines the merits of all material dimensions in heterogeneous catalysis.
      PubDate: 2017-06-06T01:30:28.197984-05:
      DOI: 10.1002/adma.201700286
       
  • Confining the Nucleation of Pt to In Situ Form (Pt-Enriched Cage)@CeO2
           Core@Shell Nanostructure as Excellent Catalysts for Hydrogenation
           Reactions
    • Authors: Shuyan Song; Xianchun Liu, Junqi Li, Jing Pan, Fan Wang, Yan Xing, Xiao Wang, Xiaogang Liu, Hongjie Zhang
      Abstract: Ultrathin (Pt-enriched cage)@CeO2 core@shell nanostructures are successfully fabricated via a facile hard-template method. It is found that the usage of Pd@Ag@CeO2 bi-metallic core@shell nanostructure as the hard template plays an important role in avoiding the independent nucleation of Pt metal during the galvanic replacement process between K2PtCl4 and Ag components. This unique core@shell samples show extraordinary activity and selectivity for the cinnamaldehyde hydrogenation reaction. It can achieve over 95% conversion with 87% selectivity of hydrocinnamaldehyde in 5 h under 1 atm H2 pressure. It is considered that such high catalytic performance could be attributed to the densely CeO2-coated core@shell hybrid form as well as the ultrathin nature of the Pt-enriched cage.High-quality CeO2-encapsulated Pt-enriched cages with ultrathin walls are successfully synthesized via a kinetic-controlled process. The products exhibit enhanced catalytic activity and selectivity for cinnamaldehyde hydrogenation reaction among the different CeO2-based core@shell samples.
      PubDate: 2017-06-06T01:20:29.215727-05:
      DOI: 10.1002/adma.201700495
       
  • Ultrahigh and Selective SO2 Uptake in Inorganic Anion-Pillared Hybrid
           Porous Materials
    • Authors: Xili Cui; Qiwei Yang, Lifeng Yang, Rajamani Krishna, Zhiguo Zhang, Zongbi Bao, Hui Wu, Qilong Ren, Wei Zhou, Banglin Chen, Huabin Xing
      Abstract: The efficient capture of SO2 is of great significance in gas-purification processes including flue-gas desulfurization and natural-gas purification, but the design of porous materials with high adsorption capacity and selectivity of SO2 remains very challenging. Herein, the selective recognition and dense packing of SO2 clusters through multiple synergistic host–guest and guest–guest interactions by controlling the pore chemistry and size in inorganic anion (SiF62−, SIFSIX) pillared metal–organic frameworks is reported. The binding sites of anions and aromatic rings in SIFSIX materials grasp every atom of SO2 firmly via Sδ+···Fδ− electrostatic interactions and Oδ−···Hδ+ dipole–dipole interactions, while the guest–guest interactions between SO2 molecules further promote gas trapping within the pore space, which is elucidated by first-principles density functional theory calculations and powder X-ray diffraction experiments. These interactions afford new benchmarks for the highly efficient removal of SO2 from other gases, even if at a very low SO2 concentration. Exceptionally high SO2 capacity of 11.01 mmol g−1 is achieved at atmosphere pressure by SIFSIX-1-Cu, and unprecedented low-pressure SO2 capacity is obtained in SIFSIX-2-Cu-i (4.16 mmol g−1 SO2 at 0.01 bar and 2.31 mmol g−1 at 0.002 bar). More importantly, record SO2/CO2 selectivity (86–89) and excellent SO2/N2 selectivity (1285–3145) are also achieved. Experimental breakthrough curves further demonstrate the excellent performance of these hybrid porous materials in removing low-concentration SO2.Selective recognition and dense packing of SO2 clusters through multiple synergistic host–guest and guest–guest interactions within SiF62−-anion-pillared hybrid porous materials sets new benchmarks for SO2 capture. The binding sites of anions and aromatic rings in SIFSIX materials grasp every atom of SO2 firmly via Sδ+···Fδ− electrostatic interactions and Oδ−···Hδ+ dipole–dipole interactions.
      PubDate: 2017-05-31T08:57:03.037049-05:
      DOI: 10.1002/adma.201606929
       
  • Simultaneous Enhancement of Charge Separation and Hole Transportation in a
           TiO2–SrTiO3 Core–Shell Nanowire Photoelectrochemical System
    • Authors: Fei Wu; Yanhao Yu, Huang Yang, Lazarus N. German, Zhenquan Li, Jianguo Chen, Weiguang Yang, Lu Huang, Weimin Shi, Linjun Wang, Xudong Wang
      Abstract: Efficient charge separation and transportation are key factors that determine the photoelectrochemical (PEC) water-splitting efficiency. Here, a simultaneous enhancement of charge separation and hole transportation on the basis of ferroelectric polarization in TiO2–SrTiO3 core–shell nanowires (NWs) is reported. The SrTiO3 shell with controllable thicknesses generates a considerable spontaneous polarization, which effectively tunes the electrical band bending of TiO2. Combined with its intrinsically high charge mobility, the ferroelectric SrTiO3 thin shell significantly improves the charge-separation efficiency (ηseparation) with minimized influence on the hole-migration property of TiO2 photoelectrodes, leading to a drastically increased photocurrent density ( Jph). Specifically, the 10 nm-thick SrTiO3 shell yields the highest Jph and ηseparation of 1.43 mA cm−2 and 87.7% at 1.23 V versus reversible hydrogen electrode, respectively, corresponding to 83% and 79% improvements compared with those of pristine TiO2 NWs. The PEC performance can be further manipulated by thermal treatment, and the control of SrTiO3 film thicknesses and electric poling directions. This work suggests a material with combined ferroelectric and semiconducting features could be a promising solution for advancing PEC systems by concurrently promoting the charge-separation and hole-transportation properties.In a TiO2–SrTiO3 core–shell nanowire photoelectrochemical (PEC) photoanode, the ferroelectric shell provides a spontaneous polarization to enhance charge separation. Meanwhile the favorable charge mobility in the shell also facilitates hole transport for water oxidation, leading to a significant enhancement of the PEC performance.
      PubDate: 2017-05-30T13:50:50.337888-05:
      DOI: 10.1002/adma.201701432
       
  • Flexible and Responsive Chiral Nematic Cellulose Nanocrystal/Poly(ethylene
           glycol) Composite Films with Uniform and Tunable Structural Color
    • Authors: Kun Yao; Qijun Meng, Vincent Bulone, Qi Zhou
      Abstract: The fabrication of responsive photonic structures from cellulose nanocrystals (CNCs) that can operate in the entire visible spectrum is challenging due to the requirements of precise periodic modulation of the pitch size of the self-assembled multilayer structures at the length scale within the wavelength of the visible light. The surface charge density of CNCs is an important factor in controlling the pitch size of the chiral nematic structure of the dried solid CNC films. The assembly of poly(ethylene glycol) (PEG) together with CNCs into smaller chiral nematic domains results in solid films with uniform helical structure upon slow drying. Large, flexible, and flat photonic composite films with uniform structure colors from blue to red are prepared by changing the composition of CNCs and PEG. The CNC/PEG(80/20) composite film demonstrates a reversible and smooth structural color change between green and transparent in response to an increase and decrease of relative humidity between 50% and 100% owing to the reversible swelling and dehydration of the chiral nematic structure. The composite also shows excellent mechanical and thermal properties, complementing the multifunctional property profile.Composite films of chiral nematic cellulose nanocrystals (CNCs) and poly(ethylene glycol) (PEG) with various uniform structural colors covering the entire visible spectrum are prepared by the intercalation of PEG between CNCs and subsequent formation of a layered helical structure upon drying. The CNC/PEG(80/20) composite film displays smooth and reversible structural color change between green and transparent when exposed to increasing and decreasing humidity conditions.
      PubDate: 2017-05-30T13:50:30.759013-05:
      DOI: 10.1002/adma.201701323
       
  • Flyweight, Superelastic, Electrically Conductive, and Flame-Retardant 3D
           Multi-Nanolayer Graphene/Ceramic Metamaterial
    • Authors: Qiangqiang Zhang; Dong Lin, Biwei Deng, Xiang Xu, Qiong Nian, Shengyu Jin, Kevin D. Leedy, Hui Li, Gary J. Cheng
      Abstract: A ceramic/graphene metamaterial (GCM) with microstructure-derived superelasticity and structural robustness is achieved by designing hierarchical honeycomb microstructures, which are composited with two brittle constituents (graphene and ceramic) assembled in multi-nanolayer cellular walls. Attributed to the designed microstructure, well-interconnected scaffolds, chemically bonded interface, and coupled strengthening effect between the graphene framework and the nanolayers of the Al2O3 ceramic (NAC), the GCM demonstrates a sequence of multifunctional properties simultaneously that have not been reported for ceramics and ceramics–matrix–composite structures, such as flyweight density, 80% reversible compressibility, high fatigue resistance, high electrical conductivity, and excellent thermal-insulation/flame-retardant performance simultaneously. The 3D well-ordered graphene aerogel templates are strongly coupled with the NAC by the chemically bonded interface, exhibiting mutual strengthening, compatible deformability, and a linearly dependent relationship between the density and Young's modulus. Considerable size effects of the ceramic nanolayers on the mechanical properties are revealed in these ceramic-based metamaterials. The designed hierarchical honeycomb graphene with a fourth dimensional control of the ceramic nanolayers on new ways to scalable fabrication of advanced multifunctional ceramic composites with controllable design suggest a great potential in applications of flexible conductors, shock/vibration absorbers, thermal shock barriers, thermal insulation/flame-retardant skins, and porous microwave-absorbing coatings.A flyweight, superelastic, electrically conductive, and flame-retardant 3D multi-nanolayer graphene/ceramic metamaterial, with microstructure-derived superelasticity and structural robustness achieved by designing hierarchical honeycomb microstructures, assembles with multi-nanolayered cellular walls of graphene and Al2O3 ceramic that serve as basic functional strengthening and elastic units.
      PubDate: 2017-05-29T04:31:21.839973-05:
      DOI: 10.1002/adma.201605506
       
  • 2D Porous Carbons prepared from Layered Organic–Inorganic Hybrids and
           their Use as Oxygen-Reduction Electrocatalysts
    • Authors: Shuang Li; Chong Cheng, Hai-Wei Liang, Xinliang Feng, Arne Thomas
      Abstract: 2D porous carbon nanomaterials have attracted tremendous attention in different disciplines especially for electrochemical catalysis. The significant advantage of such 2D materials is that nearly all their surfaces are exposed to the electrolyte and can take part in the electrochemical reaction. Here, a versatile active-salt-templating strategy to efficiently synthesize 2D porous carbon nanosheets from layered organic–inorganic hybrids is presented. The resulting heteroatom-doped carbon nanosheets (NFe/CNs) exhibit exceptional performance for the oxygen-reduction reaction and in Zn–air battery electrodes. The activity of the best catalyst within a series of NFe/CNs exceeds the performance of conventional carbon-supported Pt catalysts in terms of onset potential (0.930 vs 0.915 V of Pt/C), half-wave potential (0.859 vs 0.816 V of Pt/C), long-time stability, and methanol tolerance. Also, when applied as a cathode catalyst in a zinc–air battery the NFe/CNs presented here outperform commercial Pt/C catalysts.The formation of layered organic–inorganic hybrids and their subsequent pyrolysis is suggested as a universal and scalable strategy for the synthesis of 2D porous carbon nanosheets with well-defined 2D morphology, nanometer thickness, high surface area, and tunable heteroatom doping. These 2D carbon nanomaterials show remarkable electrocatalytic performances in the oxygen-reduction reaction and outperform commercial state-of-the-art Pt/C catalyst in zinc–air batteries.
      PubDate: 2017-05-29T04:30:57.146951-05:
      DOI: 10.1002/adma.201700707
       
  • Precise Two-Photon Photodynamic Therapy using an Efficient Photosensitizer
           with Aggregation-Induced Emission Characteristics
    • Authors: Bobo Gu; Wenbo Wu, Gaixia Xu, Guangxue Feng, Feng Yin, Peter Han Joo Chong, Junle Qu, Ken-Tye Yong, Bin Liu
      Abstract: Two-photon photodynamic therapy (PDT) is able to offer precise 3D manipulation of treatment volumes, providing a target level that is unattainable with current therapeutic techniques. The advancement of this technique is greatly hampered by the availability of photosensitizers with large two-photon absorption (TPA) cross section, high reactive-oxygen-species (ROS) generation efficiency, and bright two-photon fluorescence. Here, an effective photosensitizer with aggregation-induced emission (AIE) characteristics is synthesized, characterized, and encapsulated into an amphiphilic block copolymer to form organic dots for two-photon PDT applications. The AIE dots possess large TPA cross section, high ROS generation efficiency, and excellent photostability and biocompatibility, which overcomes the limitations of many conventional two-photon photosensitizers. Outstanding therapeutic performance of the AIE dots in two-photon PDT is demonstrated using in vitro cancer cell ablation and in vivo brain-blood-vessel closure as examples. This shows therapy precision up to 5 µm under two-photon excitation.A new two-photon photosensitizer is synthesized and formulated into organic dots with aggregation-induced emission characteristics, large two-photon absorption cross section, high reactive-oxygen-species generation efficiency, and excellent photostability and biocompatibility, enabling in vitro cancer cell ablation and in vivo brain-blood-vessel closure with 5 µm precision under two-photon excitation.
      PubDate: 2017-05-26T09:05:52.589597-05:
      DOI: 10.1002/adma.201701076
       
  • Hierarchically Enhanced Impact Resistance of Bioinspired Composites
    • Authors: Grace X. Gu; Mahdi Takaffoli, Markus J. Buehler
      Abstract: An order of magnitude tougher than nacre, conch shells are known for being one of the toughest body armors in nature. However, the complexity of the conch shell architecture creates a barrier to emulating its cross-lamellar structure in synthetic materials. Here, a 3D biomimetic conch shell prototype is presented, which can replicate the crack arresting mechanisms embedded in the natural architecture. Through an integrated approach combining simulation, additive manufacturing, and drop tower testing, the function of hierarchy in conch shell's multiscale microarchitectures is explicated. The results show that adding the second level of cross-lamellar hierarchy can boost impact performance by 70% and 85% compared to a single-level hierarchy and the stiff constituent, respectively. The overarching mechanism responsible for the impact resistance of conch shell is the generation of pathways for crack deviation, which can be generalized to the design of future protective apparatus such as helmets and body armor.An order of magnitude tougher than nacre, conch shells are known for being one of the toughest biological body armors. However, the complexity of the conch shell architecture creates a barrier to emulating its cross-lamellar structure in synthetic materials. In this paper, a 3D biomimetic conch shell prototype is presented, which can replicate the crack arresting mechanisms embedded in the natural architecture.
      PubDate: 2017-05-26T09:05:43.565882-05:
      DOI: 10.1002/adma.201700060
       
  • Reduced Interface-Mediated Recombination for High Open-Circuit Voltages in
           CH3NH3PbI3 Solar Cells
    • Authors: Christian M. Wolff; Fengshuo Zu, Andreas Paulke, Lorena Perdigón Toro, Norbert Koch, Dieter Neher
      Abstract: Perovskite solar cells with all-organic transport layers exhibit efficiencies rivaling their counterparts that employ inorganic transport layers, while avoiding high-temperature processing. Herein, it is investigated how the choice of the fullerene derivative employed in the electron-transporting layer of inverted perovskite cells affects the open-circuit voltage (VOC). It is shown that nonradiative recombination mediated by the electron-transporting layer is the limiting factor for the VOC in the cells. By inserting an ultrathin layer of an insulating polymer between the active CH3NH3PbI3 perovskite and the fullerene, an external radiative efficiency of up to 0.3%, a VOC as high as 1.16 V, and a power conversion efficiency of 19.4% are realized. The results show that the reduction of nonradiative recombination due to charge-blocking at the perovskite/organic interface is more important than proper level alignment in the search for ideal selective contacts toward high VOC and efficiency.Perovskite solar cells have emerged as one of the most promising solar-cell technologies for the next generation of photovoltaics. Despite simple and cheap processing, the solar cells exhibit comparably little loss in open-circuit voltage. An approach to further reduce this loss by optimizing the charge selectivity of the fullerene-based electron contact in efficient devices is shown.
      PubDate: 2017-05-26T00:40:34.112221-05:
      DOI: 10.1002/adma.201700159
       
  • Thermally Stable MAPbI3 Perovskite Solar Cells with Efficiency of 19.19%
           and Area over 1 cm2 achieved by Additive Engineering
    • Authors: Yongzhen Wu; Fengxian Xie, Han Chen, Xudong Yang, Huimin Su, Molang Cai, Zhongmin Zhou, Takeshi Noda, Liyuan Han
      Abstract: Solution-processed perovskite (PSC) solar cells have achieved extremely high power conversion efficiencies (PCEs) over 20%, but practical application of this photovoltaic technology requires further advancements on both long-term stability and large-area device demonstration. Here, an additive-engineering strategy is developed to realize a facile and convenient fabrication method of large-area uniform perovskite films composed of large crystal size and low density of defects. The high crystalline quality of the perovskite is found to simultaneously enhance the PCE and the durability of PSCs. By using the simple and widely used methylammonium lead iodide (MAPbI3), a certified PCE of 19.19% is achieved for devices with an aperture area of 1.025 cm2, and the high-performing devices can sustain over 80% of the initial PCE after 500 h of thermal aging at 85 °C, which are among the best results of MAPbI3-based PSCs so far.By enhancing the crystalline quality of the simple and widely used MAPbI3 perovskite through additive engineering, unprecedented photovoltaic performance and thermal stability are achieved. A certified efficiency of 19.19% is obtained for devices with active area over 1 cm2, and the high-performing devices show unprecedented durability, maintaining>80% of the initial efficiency after 500 h of thermal aging at 85 °C.
      PubDate: 2017-05-19T07:21:25.768018-05:
      DOI: 10.1002/adma.201701073
       
  • Towards Efficient Spectral Converters through Materials Design for
           Luminescent Solar Devices
    • Authors: Barry McKenna; Rachel C. Evans
      Abstract: Single-junction photovoltaic devices exhibit a bottleneck in their efficiency due to incomplete or inefficient harvesting of photons in the low- or high-energy regions of the solar spectrum. Spectral converters can be used to convert solar photons into energies that are more effectively captured by the photovoltaic device through a photoluminescence process. Here, recent advances in the fields of luminescent solar concentration, luminescent downshifting, and upconversion are discussed. The focus is specifically on the role that materials science has to play in overcoming barriers in the optical performance in all spectral converters and on their successful integration with both established (e.g., c-Si, GaAs) and emerging (perovskite, organic, dye-sensitized) cell types. Current challenges and emerging research directions, which need to be addressed for the development of next-generation luminescent solar devices, are also discussed.Sspectral converters can be applied to finished solar cells to overcome intrinsic non-absorption and thermalization losses and improve the device efficiency. Recent progress in the development of new materials for spectral conversion through luminescent downshifting, luminescent solar concentration, and upconversion is reviewed, with emphasis placed on their integration with emerging technologies, including perovskite, organic, and dye-sensitized solar cells.
      PubDate: 2017-05-19T07:16:27.682826-05:
      DOI: 10.1002/adma.201606491
       
  • Tuning of the Optical, Electronic, and Magnetic Properties of Boron
           Nitride Nanosheets with Oxygen Doping and Functionalization
    • Authors: Qunhong Weng; Dmitry G. Kvashnin, Xi Wang, Ovidiu Cretu, Yijun Yang, Min Zhou, Chao Zhang, Dai-Ming Tang, Pavel B. Sorokin, Yoshio Bando, Dmitri Golberg
      Abstract: Engineering of the optical, electronic, and magnetic properties of hexagonal boron nitride (h-BN) nanomaterials via oxygen doping and functionalization has been envisaged in theory. However, it is still unclear as to what extent these properties can be altered using such methodology because of the lack of significant experimental progress and systematic theoretical investigations. Therefore, here, comprehensive theoretical predictions verified by solid experimental confirmations are provided, which unambiguously answer this long-standing question. Narrowing of the optical bandgap in h-BN nanosheets (from ≈5.5 eV down to 2.1 eV) and the appearance of paramagnetism and photoluminescence (of both Stokes and anti-Stokes types) in them after oxygen doping and functionalization are discussed. These results are highly valuable for further advances in semiconducting nanoscale electronics, optoelectronics, and spintronics.Intense oxygen doping and functionalization of hexagonal boron nitride (h-BN) nanosheets narrow the bandgap of the material from ≈5.5 to 2.1 eV in experiments, and lead to the appearance of paramagnetism and photoluminescence properties, which are not seen in h-BN. These findings pave a new way for the engineering of the optical, electronic, and magnetic properties of BN nanosheets.
      PubDate: 2017-05-19T01:31:29.07504-05:0
      DOI: 10.1002/adma.201700695
       
  • Bioinspired Composite Microfibers for Skin Adhesion and Signal
           Amplification of Wearable Sensors
    • Authors: Dirk-M. Drotlef; Morteza Amjadi, Muhammad Yunusa, Metin Sitti
      Abstract: A facile approach is proposed for superior conformation and adhesion of wearable sensors to dry and wet skin. Bioinspired skin-adhesive films are composed of elastomeric microfibers decorated with conformal and mushroom-shaped vinylsiloxane tips. Strong skin adhesion is achieved by crosslinking the viscous vinylsiloxane tips directly on the skin surface. Furthermore, composite microfibrillar adhesive films possess a high adhesion strength of 18 kPa due to the excellent shape adaptation of the vinylsiloxane tips to the multiscale roughness of the skin. As a utility of the skin-adhesive films in wearable-device applications, they are integrated with wearable strain sensors for respiratory and heart-rate monitoring. The signal-to-noise ratio of the strain sensor is significantly improved to 59.7 because of the considerable signal amplification of microfibrillar skin-adhesive films.Strong adhesion of wearable sensors to dry and wet skin is proposed by a novel approach. Micropatterned adhesive films are composed of microfibers decorated with mushroom-shaped vinylsiloxane tips. Crosslinking the viscous tips directly on the skin significantly enhances the adhesion performance due to their great shape adaptation, which in turn highly increases the output signal quality of wearable strain sensors.
      PubDate: 2017-05-19T01:31:23.950918-05:
      DOI: 10.1002/adma.201701353
       
  • Biphasic Supramolecular Self-Assembly of Ferric Ions and Tannic Acid
           across Interfaces for Nanofilm Formation
    • Authors: Beom Jin Kim; Sol Han, Kyung-Bok Lee, Insung S. Choi
      Abstract: Cell nanoencapsulation provides a chemical tool for the isolation and protection of living cells from harmful, and often lethal, external environments. Although several strategies are available to form nanometric films, most methods heavily rely on time-consuming multistep processes and are not biocompatible. Here, the interfacial supramolecular self-assembly and film formation of ferric ions (FeIII) and tannic acid (TA) in biphasic systems is reported, where FeIII and TA come into contact each other and self-assemble across the interface of two immiscible phases. The interfacial nanofilm formation developed is simple, fast, and cytocompatible. Its versatility is demonstrated with various biphasic systems: hollow microcapsules, encasing microbial or mammalian cells, that are generated at the water–oil interface in a microfluidic device; a cytoprotective FeIII–TA shell that forms on the surface of the alginate microbead, which then entraps probiotic Lactobacillus acidophilus; and a pericellular FeIII–TA shell that forms on individual Saccharomyces cerevisiae. This biphasic interfacial reaction system provides a simple but versatile structural motif in materials science, as well as advancing chemical manipulability of living cells.The biphasic interfacial supramolecular self-assembly of ferric ions (FeIII) and tannic acid in a heterogeneous system provides a powerful method for the formation of uniform and stable nanofilms in one step. The versatility of the synthetic strategy is demonstrated under various experimental settings (water–oil, hydrogel–water, and cell–water biphasic systems).
      PubDate: 2017-05-19T01:31:16.805203-05:
      DOI: 10.1002/adma.201700784
       
  • Bioinspired Ultratough Hydrogel with Fast Recovery, Self-Healing,
           Injectability and Cytocompatibility
    • Authors: Sara Azevedo; Ana M. S. Costa, Amanda Andersen, Insung S. Choi, Henrik Birkedal, João F. Mano
      Abstract: Inspired by the mussel byssus adhesiveness, a highly hydrated polymeric structure is designed to combine, for the first time, a set of interesting features for load-bearing purposes. These characteristics include: i) a compressive strength and stiffness in the MPa range, ii) toughness and the ability to recover it upon successive cyclic loading, iii) the ability to quickly self-heal upon rupture, iv) the possibility of administration through minimally invasive techniques, such as by injection, v) the swelling ratio being adjusted to space-filling applications, and vi) cytocompatibility. Owing to these characteristics and the mild conditions employed, the encapsulation of very unstable and sensitive cargoes is possible, highlighting their potential to researchers in the biomedical field for the repair of load-bearing soft tissues, or to be used as an encapsulation platform for a variety of biological applications such as disease models for drug screening and therapies in a more realistic mechanical environment. Moreover, given the simplicity of this methodology and the enhanced mechanical performance, this strategy can be expanded to applications in other fields, such as agriculture and electronics. As such, it is anticipated that the proposed strategy will constitute a new, versatile, and cost-effective tool to produce engineered polymeric structures for both science and technology.Inspired by the mussel byssus attachment system, a self-healable, ultratough and strong hydrogel is reported. The mild conditions employed during the fabrication process, as well as the use of nature-based materials, make it a prospective candidate for a wide range of applications including in the biomedical field.
      PubDate: 2017-05-19T01:31:11.991919-05:
      DOI: 10.1002/adma.201700759
       
  • Synergistic Phase and Disorder Engineering in 1T-MoSe2 Nanosheets for
           Enhanced Hydrogen-Evolution Reaction
    • Authors: Ying Yin; Yumin Zhang, Tangling Gao, Tai Yao, Xinghong Zhang, Jiecai Han, Xianjie Wang, Zhihua Zhang, Ping Xu, Peng Zhang, Xingzhong Cao, Bo Song, Song Jin
      Abstract: MoSe2 is a promising earth-abundant electrocatalyst for the hydrogen-evolution reaction (HER), even though it has received much less attention among the layered dichalcogenide (MX2) materials than MoS2 so far. Here, a novel hydrothermal-synthesis strategy is presented to achieve simultaneous and synergistic modulation of crystal phase and disorder in partially crystallized 1T-MoSe2 nanosheets to dramatically enhance their HER catalytic activity. Careful structural characterization and defect characterization using positron annihilation lifetime spectroscopy correlated with electrochemical measurements show that the formation of the 1T phase under a large excess of the NaBH4 reductant during synthesis can effectively improve the intrinsic activity and conductivity, and the disordered structure from a lower reaction temperature can provide abundant unsaturated defects as active sites. Such synergistic effects lead to superior HER catalytic activity with an overpotential of 152 mV versus reversible hydrogen electrode (RHE) for the electrocatalytic current density of j = −10 mA cm−2, and a Tafel slope of 52 mV dec−1. This work paves a new pathway for improving the catalytic activity of MoSe2 and generally MX2-based electrocatalysts via a synergistic modulation strategy.Synergistic regulation of crystal phase and disorder engineering in partially crystallized 1T phase MoSe2 nanosheets that are directly hydrothermally synthesized enhances catalytic activity toward the hydrogen-evolution reaction (HER). The optimized MoSe2 nanosheets exhibit a record-high HER catalytic activity, with η = 152 mV versus RHE for j = −10 mA cm−2 and a Tafel slope of 52 mV dec−1.
      PubDate: 2017-05-19T01:31:07.807033-05:
      DOI: 10.1002/adma.201700311
       
  • Mushrooms as Efficient Solar Steam-Generation Devices
    • Authors: Ning Xu; Xiaozhen Hu, Weichao Xu, Xiuqiang Li, Lin Zhou, Shining Zhu, Jia Zhu
      Abstract: Solar steam generation is emerging as a promising technology, for its potential in harvesting solar energy for various applications such as desalination and sterilization. Recent studies have reported a variety of artificial structures that are designed and fabricated to improve energy conversion efficiencies by enhancing solar absorption, heat localization, water supply, and vapor transportation. Mushrooms, as a kind of living organism, are surprisingly found to be efficient solar steam-generation devices for the first time. Natural and carbonized mushrooms can achieve ≈62% and ≈78% conversion efficiencies under 1 sun illumination, respectively. It is found that this capability of high solar steam generation is attributed to the unique natural structure of mushroom, umbrella-shaped black pileus, porous context, and fibrous stipe with a small cross section. These features not only provide efficient light absorption, water supply, and vapor escape, but also suppress three components of heat losses at the same time. These findings not only reveal the hidden talent of mushrooms as low-cost materials for solar steam generation, but also provide inspiration for the future development of high-performance solar thermal conversion devices.Mushrooms can, surprisingly, enable efficient solar steam generation (≈78% under 1 sun illumination), as their natural structures possess the excellent properties of light absorption, thermal management with minimized heat loss, efficient water supply, and vapor escape.
      PubDate: 2017-05-18T07:32:05.561466-05:
      DOI: 10.1002/adma.201606762
       
  • Core–Shell and Layer-by-Layer Assembly of 3D DNA Crystals
    • Authors: Ronald McNeil; Paul J. Paukstelis
      Abstract: A long-standing goal of DNA nanotechnology has been to assemble 3D crystals to be used as molecular scaffolds. The DNA 13-mer, BET66, self-assembles via Crick–Watson and noncanonical base pairs to form crystals. The crystals contain solvent channels that run through them in multiple directions, allowing them to accommodate tethered guest molecules. Here, the first example of biomacromolecular core–shell crystal growth is described, by showing that these crystals can be assembled with two or more discrete layers. This approach leads to structurally identical layers on the DNA level, but with each layer differentiated based on the presence or absence of conjugated guest molecules. The crystal solvent channels also allow layer-specific postcrystallization covalent attachment of guest molecules. Through controlling the guest-molecule identity, concentration, and layer thickness, this study opens up a new method for using DNA to create multifunctional periodic biomaterials with tunable optical, chemical, and physical properties.Multifunctional DNA-based biomaterial solids are generated through core–shell and layer-by-layer crystal growth. The isothermal self-assembly properties of the DNA crystal allow stepwise incorporation of functionally modified oligonucleotides to create layered periodic arrays of “guest” molecules, with each layer differentiated by the identity of the tethered guest molecules.
      PubDate: 2017-05-18T07:31:58.895095-05:
      DOI: 10.1002/adma.201701019
       
  • An All-Plastic Field-Effect Nanofluidic Diode Gated by a Conducting
           Polymer Layer
    • Authors: Gonzalo Pérez-Mitta; Waldemar A. Marmisollé, Christina Trautmann, María Eugenia Toimil-Molares, Omar Azzaroni
      Abstract: The design of an all-plastic field-effect nanofluidic diode is proposed, which allows precise nanofluidic operations to be performed. The fabrication process involves the chemical synthesis of a conductive poly(3,4-ethylenedioxythiophene) (PEDOT) layer over a previously fabricated solid-state nanopore. The conducting layer acts as gate electrode by changing its electrochemical state upon the application of different voltages, ultimately changing the surface charge of the nanopore. A PEDOT-based nanopore is able to discriminate the ionic species passing through it in a quantitative and qualitative manner, as PEDOT nanopores display three well-defined voltage-controlled transport regimes: cation-rectifying, non-rectifying, and anion rectifying regimes. This work illustrates the potential and versatility of PEDOT as a key enabler to achieve electrochemically addressable solid-state nanopores. The synergism arising from the combination of highly functional conducting polymers and the remarkable physical characteristics of asymmetric nanopores is believed to offer a promising framework to explore new design concepts in nanofluidic devices.The integration of conductive poly(3,4-ethylenedioxythiophene) (PEDOT) into asymmetric solid-state nanopores leads the way to the construction of all-plastic field-effect nanofluidic diodes. The conducting layer acts as a gate electrode by changing its electrochemical state upon the application of different voltages. PEDOT-based electrochemically addressable nanofluidic devices display three well-defined voltage-controlled transport regimes: cation-rectifying, nonrectifying, and anion rectifying regimes.
      PubDate: 2017-05-18T02:02:34.368733-05:
      DOI: 10.1002/adma.201700972
       
  • Regulating Water-Reduction Kinetics in Cobalt Phosphide for Enhancing HER
           Catalytic Activity in Alkaline Solution
    • Authors: Kun Xu; Hui Ding, Mengxing Zhang, Min Chen, Zikai Hao, Lidong Zhang, Changzheng Wu, Yi Xie
      Abstract: Electrochemical water splitting to produce hydrogen renders a promising pathway for renewable energy storage. Considering limited electrocatalysts have good oxygen-evolution reaction (OER) catalytic activity in acid solution while numerous economical materials show excellent OER catalytic performance in alkaline solution, developing new strategies that enhance the alkaline hydrogen-evolution reaction (HER) catalytic activity of cost-effective catalysts is highly desirable for achieving highly efficient overall water splitting. Herein, it is demonstrated that synergistic regulation of water dissociation and optimization of hydrogen adsorption free energy on electrocatalysts can significantly promote alkaline HER catalysis. Using oxygen-incorporated Co2P as an example, the synergistic effect brings about 15-fold enhancement of alkaline HER activity. Theory calculations confirm that the water dissociation free energy of Co2P decreases significantly after oxygen incorporation, and the hydrogen adsorption free energy can also be optimized simultaneously. The finding suggests the powerful effectiveness of synergetic regulation of water dissociation and optimization of hydrogen adsorption free energy on electrocatalysts for alkaline HER catalysis.Developing highly efficient electrocatalysts in an alkaline electrolyte for the hydrogen-evolution reaction (HER) is significant for realizing efficient overall water splitting. The coordinative effect of engineering a water dissociation step and the hydrogen adsorption free energy in Co2P by oxygen incorporation can lead to 15 times enhancement of the HER catalytic activity in alkaline solution. A new strategy for the design of advanced alkaline HER electrocatalysts is thus provided.
      PubDate: 2017-05-17T06:10:35.670406-05:
      DOI: 10.1002/adma.201606980
       
  • Self-Adjusting, Polymeric Multilayered Roll that can Keep the Shapes of
           the Blood Vessel Scaffolds during Biodegradation
    • Authors: Shiyu Cheng; Yu Jin, Nuoxin Wang, Feng Cao, Wei Zhang, Wei Bai, Wenfu Zheng, Xingyu Jiang
      Abstract: A self-adjusting, blood vessel-mimicking, multilayered tubular structure with two polymers, poly(ε-caprolactone) (PCL) and poly(dl-lactide-co-glycolide) (PLGA), can keep the shape of the scaffold during biodegradation. The inner (PCL) layer of the tube can expand whereas the outer (PLGA) layers will shrink to maintain the stability of the shape and the inner space of the tubular shape both in vitro and in vivo over months. This approach can be generally useful for making scaffolds that require the maintenance of a defined shape, based on FDA-approved materials.A method to fabricate a self-adjusting, blood vessel-mimicking, multilayered structure with two polymers, poly(ε-caprolactone) (PCL) and poly(dl-lactide-co-glycolide) (PLGA), by combining electrospinning, stress-induced rolling membrane, and microfluidic techniques is reported. This structure can sustain the geometry of the artificial blood vessel over long periods of in vitro/in vivo culture due to the counteraction and mechanical balance of the PCL/PLGA layers.
      PubDate: 2017-05-17T06:06:34.290214-05:
      DOI: 10.1002/adma.201700171
       
  • Ultrahigh-Conductivity Polymer Hydrogels with Arbitrary Structures
    • Authors: Bowen Yao; Haiyan Wang, Qinqin Zhou, Mingmao Wu, Miao Zhang, Chun Li, Gaoquan Shi
      Abstract: A poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) hydrogel is prepared by thermal treatment of a commercial PEDOT:PSS (PH1000) suspension in 0.1 mol L−1 sulfuric acid followed by partially removing its PSS component with concentrated sulfuric acid. This hydrogel has a low solid content of 4% (by weight) and an extremely high conductivity of 880 S m−1. It can be fabricated into different shapes such as films, fibers, and columns with arbitrary sizes for practical applications. A highly conductive and mechanically strong porous fiber is prepared by drying PEDOT:PSS hydrogel fiber to fabricate a current-collector-free solid-state flexible supercapacitor. This fiber supercapacitor delivers a volumetric capacitance as high as 202 F cm−3 at 0.54 A cm−3 with an extraordinary high-rate performance. It also shows excellent electrochemical stability and high flexibility, promising for the application as wearable energy-storage devices.A poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) hydrogel treated by concentrated sulfuric acid shows an extraordinarily high conductivity of 880 S m−1. It can be fabricated into arbitrary structures for practical applications. A current-collector-free all-solid fiber supercapacitor based on dried fibers of this hydrogel exhibits a performance superior to those of previously reported counterparts.
      PubDate: 2017-05-17T06:05:49.103734-05:
      DOI: 10.1002/adma.201700974
       
  • Oxidized Quasi-Carbon Nitride Quantum Dots Inhibit Ice Growth
    • Authors: Guoying Bai; Zhiping Song, Hongya Geng, Dong Gao, Kai Liu, Shuwang Wu, Wei Rao, Liangqia Guo, Jianjun Wang
      Abstract: Antifreeze proteins (AFPs), a type of high-efficiency but expensive and often unstable biological antifreeze, have stimulated substantial interest in the search for synthetic mimics. However, only a few reported AFP mimics display thermal hysteresis, and general criteria for the design of AFP mimics remain unknown. Herein, oxidized quasi-carbon nitride quantum dots (OQCNs) are synthesized through an up-scalable bottom-up approach. They exhibit thermal-hysteresis activity, an ice-crystal shaping effect, and activity on ice-recrystallization inhibition. In the cryopreservation of sheep red blood cells, OQCNs improve cell recovery to more than twice that obtained by using a commercial cryoprotectant (hydroxyethyl starch) without the addition of any organic solvents. It is shown experimentally that OQCNs preferably bind onto the ice-crystal surface, which leads to the inhibition of ice-crystal growth due to the Kelvin effect. Further analysis reveals that the match of the distance between two neighboring tertiary N atoms on OQCNs with the repeated spacing of O atoms along the c-axis on the primary prism plane of ice lattice is critical for OQCNs to bind preferentially on ice crystals. Here, the application of graphitic carbon nitride derivatives for cryopreservation is reported for the first time.Oxidized quasi-carbon nitride quantum dots (OQCNs), which possess the ability to shape ice crystals and inhibit ice growth/recrystallization, are synthesized by a simple and up-scalable approach. In the cryopreservation of sheep red blood cells, OQCNs significantly improve the cell recovery to more than twice that obtained by using a commercial cryoprotectant (hydroxyethyl starch) without the addition of any organic solvents.
      PubDate: 2017-05-17T06:05:38.975214-05:
      DOI: 10.1002/adma.201606843
       
  • Brain-Inspired Photonic Neuromorphic Devices using Photodynamic Amorphous
           Oxide Semiconductors and their Persistent Photoconductivity
    • Authors: Minkyung Lee; Woobin Lee, Seungbeom Choi, Jeong-Wan Jo, Jaekyun Kim, Sung Kyu Park, Yong-Hoon Kim
      Abstract: The combination of a neuromorphic architecture and photonic computing may open up a new era for computational systems owing to the possibility of attaining high bandwidths and the low-computation-power requirements. Here, the demonstration of photonic neuromorphic devices based on amorphous oxide semiconductors (AOSs) that mimic major synaptic functions, such as short-term memory/long-term memory, spike-timing-dependent plasticity, and neural facilitation, is reported. The synaptic functions are successfully emulated using the inherent persistent photoconductivity (PPC) characteristic of AOSs. Systematic analysis of the dynamics of photogenerated carriers for various AOSs is carried out to understand the fundamental mechanisms underlying the photoinduced carrier-generation and relaxation behaviors, and to search for a proper channel material for photonic neuromorphic devices. It is found that the activation energy for the neutralization of ionized oxygen vacancies has a significant influence on the photocarrier-generation and time-variant recovery behaviors of AOSs, affecting the PPC behavior.A brain-inspired photonic neuromorphic device is demonstrated using an amorphous indium-gallium-zinc-oxide film. By utilizing the persistent photoconductivity behavior, short-term memory/long-term memory, spike-timing-dependent plasticity, and neural facilitation are emulated, which are the important synaptic functions for learning and memory. This work may open up new possibilities to realize ultrafast and massive parallel synaptic computing systems based on photonic neuromorphic devices.
      PubDate: 2017-05-17T06:05:30.883221-05:
      DOI: 10.1002/adma.201700951
       
  • A Single-Molecular AND Gate Operated with Two Orthogonal Switching
           Mechanisms
    • Authors: Na Zhang; Wai-Yip Lo, Anex Jose, Zhengxu Cai, Lianwei Li, Luping Yu
      Abstract: Single-molecular electronics is a potential solution to nanoscale electronic devices. While simple functional single-molecule devices such as diodes, switches, and wires are well studied, complex single-molecular systems with multiple functional units are rarely investigated. Here, a single-molecule AND logic gate is constructed from a proton-switchable edge-on gated pyridinoparacyclophane unit with a light-switchable diarylethene unit. The AND gate can be controlled orthogonally by light and protonation and produce desired electrical output at room temperature. The AND gate shows high conductivity when treated with UV light and in the neutral state, and low conductivity when treated either with visible light or acid. A conductance difference of 7.3 is observed for the switching from the highest conducting state to second-highest conducting state and a conductance ratio of 94 is observed between the most and least conducting states. The orthogonality of the two stimuli is further demonstrated by UV–vis, NMR, and density function theory calculations. This is a demonstration of concept of constructing a complex single-molecule electronic device from two coupled functional units.A single-molecule AND gate is constructed from two different switching mechanisms, the switch between conjugation to cross-conjugation by light and the shift of conducting orbitals by protonation. The two switches are orthogonal and can be switched reversibly. The switching ratio between the highest and lowest conductance states is 94.
      PubDate: 2017-05-17T00:30:40.332477-05:
      DOI: 10.1002/adma.201701248
       
  • Tuning Up or Down the Critical Thickness in LaAlO3/SrTiO3 through In Situ
           Deposition of Metal Overlayers
    • Authors: Diogo Castro Vaz; Edouard Lesne, Anke Sander, Hiroshi Naganuma, Eric Jacquet, Jacobo Santamaria, Agnès Barthélémy, Manuel Bibes
      Abstract: The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 and SrTiO3 has attracted much attention from the oxide electronics community. One of its hallmark features is the existence of a critical LaAlO3 thickness of 4 unit-cells (uc) for interfacial conductivity to emerge. In this paper, the chemical, electronic, and transport properties of LaAlO3/SrTiO3 samples capped with different metals grown in a system combining pulsed laser deposition, sputtering, and in situ X-ray photoemission spectroscopy are investigated. The results show that for metals with low work function a q2DES forms at 1–2 uc of LaAlO3 and is accompanied by a partial oxidation of the metal, a phenomenon that affects the q2DES properties and triggers the formation of defects. In contrast, for noble metals, the critical thickness is increased above 4 uc. The results are discussed in terms of a hybrid mechanism that incorporates electrostatic and chemical effects.The possibility to tune up or down the critical thickness at which a 2D electron gas appears at the LaAlO3/SrTiO3 interface, by capping the LaAlO3 with different metals is demonstrated. Besides electrostatic effects, X-ray photoemission spectroscopy reveals the importance of the partial oxidation of the metal on the properties of the gas.
      PubDate: 2017-05-15T11:50:34.560448-05:
      DOI: 10.1002/adma.201700486
       
  • Recent Progress in the Design of Advanced Cathode Materials and Battery
           Models for High-Performance Lithium-X (X = O2, S, Se, Te, I2, Br2)
           Batteries
    • Authors: Jiantie Xu; Jianmin Ma, Qinghua Fan, Shaojun Guo, Shixue Dou
      Abstract: Recent advances and achievements in emerging Li-X (X = O2, S, Se, Te, I2, Br2) batteries with promising cathode materials open up new opportunities for the development of high-performance lithium-ion battery alternatives. In this review, we focus on an overview of recent important progress in the design of advanced cathode materials and battery models for developing high-performance Li-X (X = O2, S, Se, Te, I2, Br2) batteries. We start with a brief introduction to explain why Li-X batteries are important for future renewable energy devices. Then, we summarize the existing drawbacks, major progress and emerging challenges in the development of cathode materials for Li-O2 (S) batteries. In terms of the emerging Li-X (Se, Te, I2, Br2) batteries, we systematically summarize their advantages/disadvantages and recent progress. Specifically, we review the electrochemical performance of Li-Se (Te) batteries using carbonate-/ether-based electrolytes, made with different electrode fabrication techniques, and of Li-I2 (Br2) batteries with various cell designs (e.g., dual electrolyte, all-organic electrolyte, with/without cathode-flow mode, and fuel cell/solar cell integration). Finally, the perspective on and challenges for the development of cathode materials for the promising Li-X (X = O2, S, Se, Te, I2, Br2) batteries is presented.Emerging Li-X (X = O2, S, Se, Te, I2, Br2) batteries with promising cathode materials open up new opportunities for the development of high-performance lithium-ion battery alternatives. Here, an overview of recent important progress in the design of advanced cathode materials and battery models for developing high-performance Li-X batteries is presented.
      PubDate: 2017-05-10T06:16:16.996339-05:
      DOI: 10.1002/adma.201606454
       
 
 
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