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High-Quality and Strain-relaxation GaN Epilayer Grown on SiC Substrates Using AIN Buffer and AlGaN Interlayer

Chinese Physics Letters 2017年第4期34卷 108-111页

作者： Bo-Ting Liu Shi-Kuan Guo Ping Ma Jun-Xi Wang Jin-Min Li Semiconductor Lighting R&D Center Institute of SemiconductorsChinese Academy of SciencesBeijing 100083 College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 100049 State Key Laboratory of Solid State Lighting Beijing 100083 Beijing Engineering Research Center for the Third-Generation Semiconductor Materials and Application Beijing 100083

We study the effect of the AlGaN interlayer on structural quality and strain engineering of the GaN films grown on SiC substrates with an AlN buffer layer, hnproved structural quality and tensile stress releasing are realized in unintentionally doped GaN thin films grown on 6H-SiC substrates by metal organic chemical vapor deposition. Using the optimized AlGaN interlayer, we find that the full width at half maximum of x-ray diffraction peaks for GaN decreases dramatically, indicating an improved crystalline quality. Meanwhile, it is revealed that the biaxial tensile stress in the GaN film is significantly reduced from the raman results. Photoluminescence spectra exhibit a shift of the peak position of the near-band-edge emission, as well as the integrated intensity ratio variation of the near-band-edge emission to the yellow luminescence band. Thus by optimizing the AlGaN interlayer, we could acquire the high-quality and strain-relaxation GaN epilayer with large thickness on SiC substrates.

关键词： AlGaN In High-Quality and Strain-relaxation GaN Epilayer Grown on SiC Substrates Using AIN Buffer and AlGaN Interlayer SiC AIN

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Influence of Al Preflow Time on Surface Morphology and Quality of AlN and GaN on Si(111) Grown by MOCVd

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Chinese Physics Letters 2017年第5期34卷 119-123页

作者：刘波亭马平李喜林王军喜李晋闽 Semiconductor Lighting R&D Center Institute of SemiconductorsChinese Academy of SciencesBeijing 100083 College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 100049 State Key Laboratory of Solid State Lighting Beijing 100083 Beijing Engineering Research Center for the Third-Generation Semiconductor Materials and Application Beijing 100083

We investigate the influence of A1 preflow time on surface morphology and quality of AIN and GaN. The AIN and GaN layers are grown on a Si （111） substrate by metal organic chemical vapor deposition. Scanning electron microscopy, atomic force microscopy, x-ray diffraction and optical microscopy are used for analysis. Consequently, we find significant differences in the epitaxial properties of AlN buffer and the GaN layer, which are dependent on the AI preflow time. A1 preflow layers act as nucleation sites in the case of AiN growth. Compact and uniform AIN nucleation sites are observed with optimizing A1 preflow at an early nucleation stage, which will lead to a smooth AIN surface. Trenches and AlN grain clusters appear on the AIN surface while meltoback etching occurs on the GaN surface with excessive A1 preflow. The GaN quality variation keeps a similar trend with the AIN quality, which is influenced by AI preflow. With an optimized duration orAl preflow, crystal quality and surface morphology of AIN and GaN could be improved.

关键词： GaN AlN AIN Grown by MOCVd Influence of Al Preflow Time on Surface Morphology and Quality of AlN and GaN on Si Si

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diels–Alder polymer Networks with Temperature-reversible Cross-Linking-Induced Emission

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Angewandte Chemie 2020年第1期133卷

作者： Prof. dr. Yu Jiang Prof. dr. Nikos Hadjichristidis Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science Hubei R&D Center of Hyperbranched Polymers Synthesis and Applications South-Central University for Nationalities Wuhan 430074 China Polymer Synthesis Laboratory KAUST Catalysis Center Physical Sciences and Engineering Division King Abdullah University of Science and Technology (KAUST) Thuwal 23955 Saudi Arabia

A novel synthetic strategy gives reversible cross-linked polymeric materials with tunable fluorescence properties. dimaleimide-substituted tetraphenylethene (TPE-2MI), which is non-emissive owing to the photo-induced electron transfer (PET) between maleimide (MI) and tetraphenylethene (TPE) groups, was used to cross-link random copolymers of methyl (MM), decyl (dM) or lauryl (LM) methacrylate with furfuryl methacrylate (FM). The mixture of copolymer and TPE-2MI in dMF showed reversible fluorescence with “on/off” behavior depending on the diels–Alder (dA)/retro-dA process, which is easily adjusted by temperature. At high temperatures, the retro-dA reaction is dominant, and the fluorescence is quenched by the photo-induced electron transfer (PET) mechanism. In contrast, at low temperatures, the emission recovers as the dA reaction takes over. A transparent PMFM/TPE-2MI polymer film was prepared which shows an accurate response to the external temperature and exhibited tunable fluorescent “turn on/off” behavior. These results suggest the possible application in areas including information security and transmission. An example of invisible/visible writing is given.

关键词： cross-linking-induced emission diels–Alder reaction polymers reversible photoluminescence temperature response

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Inside Back Cover: diels–Alder polymer Networks with Temperature-reversible Cross-Linking-Induced Emission (Angew. Chem. Int. Ed. 1/2021)

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Angewandte Chemie International Edition 2020年第1期60卷

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High-damping and conducting epoxy nanocomposite using both zinc oxide particles and carbon nanofibers

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Journal of Materiomics 2018年第3期4卷 187-193页

作者： Jae-Soon Jang Gyo Woo Lee Hyung-ick Kim Sung Yong Hong Lijie Ci Jae-do Nam Jonghwan Suhr Simulation Group Battery R&D CenterSAMSUNG SDI CO.LTDSamsung-RoYeongtong-GuSuwon-SiGyeonggi-DoSouth Korea Division of Mechanical Design Engineering Chonbuk National UniversityJeonju561-756South Korea Dongnam Regional Division Korea Institute of Industrial TechnologyJinju 52845South Korea Department of Polymer Science and Engineering Sungkyunkwan University2066SeoburoJangan-guGyeonggi-doSouth Korea School of Materials Science&Engineering Shandong UniversityChina School of Mechanical Engineering Sungkyunkwan University2066SeoburoJangan-guGyeonggi-doSouth Korea Department of Energy Science Sungkyunkwan University2066SeoburoJangan-guGyeonggi-doSouth Korea

In this study,high-damping and conducting epoxy nanocomposites were developed with carbon nanofibers as conducting materials,and zinc oxide particles as piezoelectric *** mechanical and electrical properties,electrical impedance,and loss factors were investigated by uniaxial tensile tests,voltage measurement,impedance measurement,and 3-point bending *** percolation thresholds were found:the percolation threshold of resistivity due to the carbon nanofibers forming conductive networks in the matrix;and the impedance threshold due to the zinc oxide particles acting like electric barriers.A poling treatment of the high-damping and conducting epoxy nanocomposite was considered,and we found that poling treatment helped to make the networks more conductive and to generate voltage from ZnO particles.A high-damping and conducting epoxy nanocomposite with 3 wt%CNF and 10 wt%ZnO exhibited higher loss factor than those of others tested.

关键词： damping Piezoelectric materials Impedance Poling treatment Loss factor

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Activating Nitrogen-doped Graphene Oxygen reduction Electrocatalysts in Acidic Electrolytes using Hydrophobic Cavities and Proton-conductive Particles

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Angewandte Chemie 2022年第51期134卷

作者： dr. Santosh K. Singh dr. Kotaro Takeyasu Kaito Homma Prof. Shigeharu Ito Prof. Takashi Morinaga Yuto Endo Moeko Furukawa dr. Toshiyuki Mori dr. Hirohito Ogasawara Prof. Junji Nakamura Graduate School of Science and Technology University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8573 Japan Department of Chemistry School of Natural Sciences Shiv Nadar University Delhi-NCR Greater Noida Uttar Pradesh 201314 India Faculty of Pure and Applied Sciences University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8573 Japan Tsukuba Research Centre for Energy and Materials Science University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8573 Japan R&D Center for Zero CO2 Emission with Functional Materials University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8573 Japan Department of Creative Engineering National Institute of Technology (KOSEN) Tsuruoka College 104 Sawada Inooka Tsuruoka Yamagata 997-8511 Japan Center for Green Research on Energy and Environmental Materials National Institute for Materials Sciences (NIMS) 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park CA 94025 USA Faculty of Faculty of Pure and Applied Sciences University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8573 Japan Mitsui Chemicals Inc.—Carbon Neutral Research Center (MCI–CNRC) International Institute for Carbon-Neutral Energy Research (I2CNER) Kyushu University 744 Motooka Nishi-ku Fukuoka-shi Fukuoka 819-0395 Japan

Although pyridinic-nitrogen (pyri-N) doped graphene is highly active for the oxygen reduction reaction (Orr) of fuel cells in alkaline media, the activity critically decreases under acidic conditions. We report on how to prevent the deactivation based on the mechanistic understanding that governs the Orr kinetics. First, we considered that the deactivation is due to the hydration of pyri-NH + , leading to a lower shift of the redox potential. Introducing the hydrophobic cavity prevented the hydration of pyri-NH + but inhibited the proton transport. We then increased proton conductivity in the hydrophobic cavity by introducing SiO 2 particles coated with ionic liquid polymer/Nafion® which kept the high onset potentials with an increased current density even in acidic media.

关键词： Fuel Cell N-doped Graphene Catalyst Oxygen reduction reaction

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Photocatalytic Cr(Ⅵ) reduction and organic-pollutant degradation in a stable 2d coordination polymer

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Chinese Journal of Catalysis 2017年第12期38卷 2141-2149页

作者： Fu‐Xue Wang Xiao‐Hong Yi Chong‐Chen Wang Ji‐Guang deng Beijing Key Laboratory of Functional Materials for Building Structure and Environment Remediation/Sino‐Dutch R&D Centre for Future Wastewater Treatment Technologies Beijing University of Civil Engineering and Architecture Beijing 100044 China Department of Chemistry and Chemical Engineering College of Environmental and Energy Engineering Beijing University of Technology Beijing 100022 China

A new coordination polymer,Zn(bpy)L(BUC‐21),(H2L=cis‐1,3‐dibenzyl‐2‐imidazolidone‐4,5‐dicarboxylic acid,bpy=4,4′‐bipyridine),has been synthesized under hydrothermal conditions,and characterized by single‐crystal X‐ray analysis,Fourier transform infrared spectroscopy,thermogravimetric analyses,CNH elemental analysis and UV‐Vis diffuse reflectance ***‐21exhibited an excellent performance for photocatalytic Cr(VI)reduction with a conversion efficiency of96%,better than that of commercial P25(39%),under UV light irradiation ***‐21could also be used to conduct photocatalytic degradation of organic dyes including methylene blue,rhodamine B,methyl orange and reactive red X‐***,the photocatalytic activity of BUC‐21remained high across a wide pH range *** is interesting to note,however,that BUC‐21was unable to achieve simultaneous reduction of Cr(VI)and degradation of an organic pollutant in a mixed matrix,which can be attributed to the competition between Cr(VI)and the organic dyes for access to the photo‐excited electrons.

关键词： Photocatalysis Cr(VI) reduction Organic dyes Coordination polymers degradation

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Optical Films: Latticework Nanostructure by Chemical Function Transfer and Molecular Shape Amplification of Programmed reactive Mesogens (Adv. Funct. Mater. 44/2019)

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Advanced functional materials 2019年第44期29卷

作者： Yu‐Jin Choi Yumin Lee Geukcheon Bang Jinyoung Jeong Namil Kim Ji‐Hoon Lee Kwang‐Un Jeong Department of Polymer‐Nano Science and Technology Department of BIN Convergence Technology Chonbuk National University Jeonju 54896 Republic of Korea Division of Electronics Engineering Chonbuk National University Jeonju 54896 Republic of Korea Environmental Materials R&D Center Korea Automotive Technology Institute Cheonan 330‐912 Republic of Korea

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functionalized graphene oxide-reinforced electrospun carbon nanofibers as ultrathin supercapacitor electrode

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Journal of Energy Chemistry 2017年第4期26卷 790-798页

作者： W.K.Chee H.N.Lim Y.Andou Z.Zainal A.A.B.Hamra I.Harrison M.Altarawneh Z.T.Jiang N.M.Huang Department of Chemistry Faculty of ScienceUniversiti Putra Malaysia Functional Device Laboratory Institute of Advanced TechnologyUniversiti Putra Malaysia Graduate School of Life Science and Systems Engineering Eco-Town Collaborative R&D Center for the Environment and RecyclingKyushu Institute of Technology Department of Electrical and Electronic Engineering Faculty of EngineeringUniversity of Nottingham Surface Analysis and Materials Engineering Research Group School of Engineering and Information TechnologyMurdoch University Faculty of Engineering Xiamen University of Malaysia

Graphene oxide has been used widely as a starting precursor for applications that cater to the needs of tunable graphene. However, the hydrophilic characteristic limits their application, especially in a hydrophobic condition. Herein, a novel non-covalent surface modification approach towards graphene oxide was conducted via a UV-induced photo-polymerization technique that involves two major routes; a UV-sensitive initiator embedded via pi-pi interactions on the graphene planar rings, and the polymerization of hydrophobic polymeric chains along the surface. The functionalized graphene oxide successfully achieved the desired hydrophobicity as it displayed the characteristic of being readily dissolved in organic solvent. Upon its addition into a polymeric solution and subjected to an electrospinning process,non-woven random nanofibers embedded with graphene oxide sheets were obtained. The prepared polymeric nanofibers were subjected to two-step thermal treatments that eventually converted the polymeric chains into a carbon-rich conductive structure. A unique morphology was observed upon the addition of the functionalized graphene oxide, whereby the sheets were embedded and intercalated within the carbon nanofibers and formed a continuous structure. This reinforcement effectively enhanced the electrochemical performance of the carbon nanofibers by recording a specific capacitance of up to 140.10 F/g at the current density of 1 A/g, which was approximately three folds more than that of pristine *** also retained the capacitance up to 96.2% after 1000 vigorous charge/discharge cycles. This functionalization technique opens up a new pathway in tuning the solubility nature of graphene oxide towards the synthesis of a graphene oxide-reinforced polymeric structure.

关键词： Non-covalent functionalization functionalized graphene oxide Electrospinning Carbon nanofiber Supercapacitor electrode

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Osseointegration: Long‐Term Prevention of Bacterial Infection and Enhanced Osteoinductivity of a Hybrid Coating with Selective Silver Toxicity (Adv. Healthcare Mater. 5/2019)

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Advanced Healthcare materials 2019年第5期8卷

作者： Kai Xie Ziao Zhou Yu Guo Lei Wang Guoyuan Li Shuang Zhao Xiangmei Liu Jun Li Wenbo Jiang Shuilin Wu Yongqiang Hao Shanghai Key Laboratory of Orthopaedic Implants Department of Orthopaedic Surgery Shanghai Ninth People's Hospital Shanghai Jiao Tong University School of Medicine Shanghai 200011 China Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials Hubei Key Laboratory of Polymer Materials School of Materials Science & Engineering Hubei University Wuhan 430062 China School of Materials Science & Engineering the Key Laboratory of Advanced Ceramics and Machining Technology by the Ministry of Education of China Tianjin University Tianjin 300072 China Clinical and Translational Research Center for 3D Printing Technology Shanghai Ninth People's Hospital Shanghai Jiao Tong University School of Medicine Shanghai 200011 China

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