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Vacancy-Based Defect Regulation for High Thermoelectric Performance in Ge9Sb2Te12-x Compounds

ACS APPLIED materials & INTERFACES 2020年第17期12卷 19664-19673页

作者： Chen, Shuo Bai, Hui Li, Junjie Pan, Wenfeng Jiang, Xianyan Li, Zhi Chen, Zhiquan Yan, Yonggao Su, Xianli Wu, Jinsong Uher, Ctirad Tang, Xinfeng State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China Hubei Nuclear Solid Physics Key Laboratory Department of Physics Wuhan University Wuhan 430072 China Hubei Nuclear Solid Physics Key Laboratory Department of Physics Wuhan University Wuhan 430072 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China Hubei Nuclear Solid Physics Key Laboratory Department of Physics Wuhan University Wuhan 430072 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China Department of Physics University of Michigan Ann Arbor Michigan 48109 United States State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Defect engineering is the core strategy for improving thermoelectric properties. Herein, cation doping along with modulation of cation vacancy has been developed in GeTe-based materials as an effective method to induce vacancy-based defects to boost their thermoelectric performance. A series of ternary compounds of Ge9Sb2Te12-x (x = 0, 0.03, 0.06, 0.09, 0.12, 0.15) was prepared by vacuum-melting and annealing combined with the spark plasma sintering (SPS) process. The role of Sb doping and cation vacancy on thermoelectric properties was systematically investigated. It is found that alloying Sb2Te3 into GeTe increases the concentration of cation vacancies, which is corroborated by both positron annihilation measurements and theoretical calculations. The vacancies, stacking faults, and planar defect interactions determine the thermoelectric transport properties. Adjusting the deficiency of Te effectively tunes the concentration of cation vacancies and dopant defects in the structure. In turn, this tunes the carrier concentration close to its optimum. A high power factor of 32.6 mu W cm(-1) K-2 is realized for Ge9Sb2Te11.91 at 725 K. Moreover, large strains induced by the defect structures, including Sb dopant, vacancy, staking faults, as well as planar defects intensify phonon scattering, leading to a significant decrease in the thermal conductivity from 7.6 W m(-1) K-1 for pristine GeTe to Ge9Sb2Te11.85 at room temperature. All of the above contribute to a high ZT value of 2.1 achieved for the Ge9Sb2Te11.91 sample at 775 K.

关键词： GeTe-based compounds alloying with Sb2Te3 deficiency of Te stacking fault vacancy plane thermoelectric

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Molecular Engineering of g-C_(3)N_(4)with Dibenzothiophene Groups as Electron Donor for Enhanced Photocatalytic H_(2)-Production

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Chinese Journal of Structural Chemistry 2022年第6期41卷 48-54页

作者： Shanren Tao Sijie Wan Qinyang Huang Chengming Li Jiaguo Yu Shaowen Cao State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

The construction of donor-acceptor(D-A)molecular structure is an attractive strategy to enhance the photocatalytic performance of polymeric ***,dibenzothiophene(DBT)-4-carbaldehyde as the precursor is introduced into g-C_(3)N_(4)(TCN)prepared by two-step thermal polymerization to construct an intramolecular D-A type copolymer(TCN-DBT_(x)).DFT calculation and experimental results reveal that DBT plays the role of electron donor unit to modify g-C_(3)N_(4).The incorporation of DBT not only adjusts the band gap to improve reduction ability,but also induces an internal electric field with extendingπ-conjugated system for effective charge *** a result,TCN-DBT_(x)exhibits much better photocatalytic performance with an optimal hydrogen production rate of 3334μmol h^(-1)g^(-1),which is 2.5 times that of *** work provides a protocol for preparing high-performance g-C_(3)N_(4)-based photocatalysts toward various applications.

关键词： carbon nitride donor-acceptor photocatalysis charge transfer

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P-doped Germanium Nanowires with Fanobroadening in Raman Spectrum

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Journal of Wuhan University of technology(materials Science) 2016年第1期31卷 52-57页

作者：何亮 xiong biao zhou peng luo wen song peishuai wang xukun hao zhimeng yang xiao niu chaojiang tian xiaocong yan mengyu 麦立强 State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

The optimized growth conditions for high density germanium（Ge） nanowires and P-doped Ge nanowires on Si（111） substrate were investigated,the phosphorus（P）-doping in Ge nanowires was also *** liquid solid-low pressure chemical vapor deposition（VLS-LPCVD） of Ge nanowires was conducted with different thicknesses of Au film as catalyst,different flow rates of GeH4 as precursor and PH3/Ar as *** morphologies of the Ge nanowires were characterized by scanning electron microscopy（SEM）,the P-doping was verified by micro Raman spectroscopy via measuring the P local vibrational peak（342-345 cm^（-1）） and asymmetric broadening of Ge-Ge vibrational peak（about 300 cm^（-1）,*** characterization results show that 1 run thickness of Au catalyst is the most suitable condition among thicknesses of 0.1,1,5,and 10 nm for the growth of high density Ge nanowires at 300 and 350℃,and 0.5 sccm is the best flow rate of PH3/Ar to grow high density and large scale P-doped Ge nanowires among flow rates of 0.5,1 and *** P impurity can be doped into Ge nanowires effectively during LPCVD process at 350 ℃.

关键词： germanium nanowires LPCVD doping VLS

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Effect of Outer Carbon Layer Thickness of Carbon-covered N-doped Hollow Carbon Nanospheres on Its Electrocatalytic Performance

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Journal of Wuhan University of technology(materials Science) 2021年第2期36卷 166-173页

作者： TAO Bowen PAN Xiangchuan ZHANG Haining State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

Hollow nitrogen-doped porous carbon materials covered with different thicknesses of carbon layers were synthesized to assist evaluation of the influence of nitrogen atom on the surrounding carbon *** designed carbon-based materials were synthesized through pyrolysis of surface-attached block copolymer layers on silica nanoparticles with different thicknesses of the second block of grafted polymer chains,followed by removal of silica *** experimental results reveal that coverage a carbon layer with proper thickness can improve the oxygen reaction reduction activity of nitrogen-doped carbon materials as evidenced by the positive shift of half-wave potential in linear scanning voltammetry response *** conclusions may provide a reference work on understanding the active sites and designing materials with superior electrochemical performance.

关键词： surface-attachment porous carbon block copolymers surface coverage oxygen reduction reaction

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synthesis of Ti_2AlC by hot pressing and its mechanical and electrical properties

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中国有色金属学会会刊：英文版 2007年第5期17卷 1001-1004页

作者：王苹梅炳初洪小林周卫兵 School of Science Wuhan University of Technology State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology

Ti2AlC bulk material was synthesized by hot pressing of mixture powders of TiC, Ti, Al and active carbon. The phase compositions of resultant product at different temperature were detected by X-ray diffractometer. The microstructures of the samples were observed by SEM. Finally, the mechanical properties and thermal properties of the sample at 1400 ℃ were measured. The results show that high purity Ti2AlC material with little Ti3AlC2 can be synthesized by hot pressing 0.5TiC/1.5Ti/1.0Al/0.5C at 1 400 ℃. Ti2AlC exhibits high mechanical properties and metallic electrical properties. Its fracture toughness is 7.0 MPa·m1/2, its flexural strength is 384 MPa at room temperature, and its electrical conductivity is 2.56×106 Ω1·m-1 at room temperature.

关键词：热压制 Ti2AlC 机械力学电工材料

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Microstructure and Mechanical Property of (TiNbTaZrHf)C Synthesized by In-situ Reaction

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Journal of Wuhan University of technology(materials Science) 2022年第2期37卷 177-183页

作者： ZHOU Qing ZHANG Jinyong FU Zhengyi WANG Dangqiang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

The(TiNbTaZrHf)C high entropy carbide(HEC)was successfully synthesized by complete commercial transition metal powders,obtained fine sintered bulks without additives by in-situ reaction element synthesis method.(TiNbTaZrHf)C bulk shows a face centered cubic rock salt structure with homogeneous single-phase FCC structure in composition and *** optimum sintering temperature is about 1900℃at which the best mechanical properties are *** mechanical properties of(TiNbTaZrHf)C ceramic block are better than those of binary transition metal carbides,and it has obvious high entropy *** a small amount of Al as sintering additive,the mechanical properties of(TiNbTaZrHf)C ceramics continue to improve,the bending strength of the samples at each temperature is increased by at least 38%,and the highest is 486 *** elastic modulus and hardness of the sample at 1900℃are also slightly increased by 4%and 14%,*** above conclusions illustrate that the properties of high entropy ceramics are greatly improved by in-situ reaction sintering.

关键词： high entropy carbide in-situ reaction microstructure mechanical property sintering additive

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Fabrication of BiVO4：Effect of Structure and Morphology on Photocatalytic Activity and Its Methylene Blue Decomposition Mechanism

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Journal of Wuhan University of technology(materials Science) 2016年第4期31卷 791-798页

作者：郭敏娜 he qianglong wang wenjie wu jie 王为民 State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

BiVO4 photocatalysts were synthesized by a surfactant free hydrothermal method without any further treatments,and characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,ultraviolet-visible diffuse reflectance spectroscopy（UV-vis DRS）,Raman spectroscopy,and Brunauer-Emmett-Teller（BET） surface area *** photocatalytic activity was evaluated for the degradation of the methylene blue（MB） under visible light *** from the structural and morphological characterization,it is stated that the obtained samples present monoclinic phase,and the pH value has significant influence on the *** enhanced photocatalytic performance was associated with its crystallinity,unique morphology,band gap energy,BET specific surface area,surface charge and adsorption *** recycle experiments results show that the BiVO4 photocatalysts have excellent photo-stability,and we deduced a possible mechanism by examining the effects of the active species involved in the photocatalytic process for MB photocatalytic degradation.

关键词： photocatalytic surfactant hydrothermal visible crystallinity ultraviolet irradiation Brunauer tetragonal Teller

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Nitrogen-doped Porous Carbon Derived from Surface-attached Polymer Layers for Oxygen Reduction Reaction under Acidic Conditions

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Journal of Wuhan University of technology(materials Science) 2017年第6期32卷 1287-1292页

作者：潘向川 BOAKYE Felix Ofori LIU Kai 张海宁 State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

We reported the synthesis of nitrogen-doped carbon using surface-attached polyelectrolyte layers as precursors. The synthesized material has a large surface area of 800 m^2·g^-1 with uniformed pore distribution. Benefitfed from the high pyridinic nitrogen content, the synthesized nitrogen-doped porous carbon material exhibits promising electrocatalytic activity toward oxygen reduction reactions in acidic medium and very high stability against continuous cyclic voltammetry scans. The experimental results demonstrate that surface-attached polyelectrolyte layers are promising carbon and nitrogen sources for the formation of heteroatom-doped porous carbon materials.

关键词： mesoporous materials polyelectrolyte carbon surface-attachment oxygen reduction stability

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Phenylenediamine-formaldehyde chemistry derived N-doped hollow carbon spheres for high-energy-density supercapacitors

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Chinese Chemical Letters 2021年第1期32卷 184-189页

作者： Ming Xu Yuheng Liu Qiang Yu Shihao Feng Liang Zhou Liqiang Mai State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

Porous carbon spheres represent an ideal family of electrode materials forsupercapacitors because of the high surface area,ideal conductivity,negligible aggregation,and ability to achieve space efficient ***,the development of new synthetic methods towards porous carbon spheres still remains a great ***,N-doped hollow carbon spheres with an ultrahigh surface area of2044 m^(2)/g have been designed based on the phenylenediamine-formaldehyde *** applied in symmetric supercapacitors with ionic electrolyte(EMIBF_4),the obtained N-doped hollow carbon spheres demonstrate a high capacitance of 234 F/g,affording an ultrahigh energy density of 114.8 Wh/*** cycling stability has also been *** impressive capacitive performances make the phenylenediamine-formaldehyde resin derived N-doped carbon a promising candidate electrode material for supercapacitors.

关键词： Porous carbon spheres Hollow structure Supercapacitors Ionic electrolyte Energy density

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Bioprocess-inspired Fabrication of Lead Iodide Coexisting with Crystalline Nanosheet and Amorphous Nanorod for Perovskite Solar Cells

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Journal of Wuhan University of technology(materials Science) 2021年第3期36卷 358-363页

作者： CHI Wenhao ZHU Yuexu FU Zhengyi XIE Jingjing State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

A recombinant protein ChiSifiCa,which was originally designed for regulation of calcium carbonate,was utilized to direct the mineralization of PbI_(2).By the regulation of ChiSifiCa protein,PbI_(2)nanoparticles composed of crystalline nanoflakes and amorphous nanorods were fabricated under environmental benign *** PbI_(2)was successfully applied for preparation of perovskite precursors to fabricate solar *** regulation of ChiSifiCa on PbI_(2)improves the power conversion efficiency of corresponding perovskite solar cells to 16%.The present study may open a new avenue in the design and synthesis of materials with novel structures and functions.

关键词： bioprocess-inspired fabrication biomineralization ChiSifiCa protein lead iodide perovskite solar cells

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