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Confined Ultrafine Pt in Porous Carbon Fibers and Their N-Enhanced Heavy d-π Effect

Chemistry of materials 2022年第8期34卷 3705-3714页

作者： Yu-Xuan Xiao Jie Ying Jiang-Bo Chen Yuan Dong Xiong Yang Ge Tian Jinsong Wu Christoph Janiak Kenneth I. Ozoemena Xiao-Yu Yang School of Chemical Engineering and Technology Sun Yat-sen University Zhuhai 519082 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing & School of Materials Science and Engineering & NRC (Nanostructure Research Centre) Wuhan University of Technology Wuhan 430070 China Institut für Anorganische Chemie und Strukturchemie Heinrich-Heine-Universität Düsseldorf Düsseldorf 40204 Germany Molecular Sciences Institute School of Chemistry University of the Witwatersrand Johannesburg 2050 South Africa School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 United States

The heavy d-π effect is an important theoretical model for strong Pt–C interaction, and its enhancement is critical to the high-performance design of Pt/C electrocatalysts. Common chemical N-doping to the carbon support can provide possibilities for enhanced electrocatalysis but most often leads to random interaction with Pt nanoparticles (Pt-NPs) and uncontrollable tuning of the heavy d-π effect. Directional confinement of Pt-NPs within N-doped carbon to directly enhance the heavy d-π effect is therefore mostly preferred but rarely reported. Herein, confined ultrafine Pt-NPs in N-doped porous carbon fibers (Pt@NDPCF) were obtained by a combination method involving electrospinning, carbonization, and directional replacement. Such a synthetic strategy leads to highly dispersed, ultrafine Pt-NPs in hierarchically porous carbon fibers and a strong directional interaction of Pt with pyridinic N, which significantly enhances the heavy d-π effect, greatly facilitating electron transfer and optimizing Pt 5d orbitals. Based on these advances, Pt@NDPCF exhibited outstanding activity and superior durability in the hydrogen evolution reaction (HER), with 24 mV lower overpotential at 10 mA cm–2and a much smaller activity loss after 10,000 cycles of durability tests in comparison with a commercial Pt/C catalyst. This work sheds new lights on the design of high-performance Pt-based nanomaterials toward HER or other practical applications.

关键词： Carbon Carbon fiber Evolution reactions Metal organic frameworks Platinum

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Spatial Heterojunction in Nanostructured TiO2 and Its Cascade Effect for Efficient Photocatalysis

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Nano letters 2020年第5期20卷 3122-3129页

作者： Yi Lu Xiao-Long Liu Li He Yue-Xing Zhang Zhi-Yi Hu Ge Tian Xiu Cheng Si-Ming Wu Yuan-Zhou Li Xiao-Hang Yang Li-Ying Wang Jia-Wen Liu Christoph Janiak Gang-Gang Chang Wei-Hua Li Gustaaf Van Tendeloo Xiao-Yu Yang Bao-Lian Su State Key Laboratory of Advanced Technology for Materials Synthesis and Processing & School of materials science and engineering & School of Chemistry Chemical Engineering and Life Science Wuhan University of Technology Wuhan 430070 China. Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) & School of Chemical Engineering and Technology School of Materials Sun Yat-sen University Zhuhai 519000 China. Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials Ministry-of-Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules College of Chemistry and Chemical Engineering Hubei University Wuhan 430062 China. Nanostructure Research Centre Wuhan University of Technology Wuhan 430070 China. Electron Microscopy for Materials Science University of Antwerp Antwerpen B-2020 Belgium. College of Chemistry Jilin University Changchun 130023 China. State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics The Chinese Academy of Sciences Wuhan 430071 China. Institut für Anorganische Chemie und Strukturchemie Heinrich-Heine-Universität Düsseldorf Düsseldorf 40204 Germany. School of Engineering and Applied Sciences Harvard University Cambridge 02138 Massachusetts United States. Laboratory of Inorganic Materials Chemistry University of Namur Namur B-5000 Belgium.

A highly efficient photoenergy conversion is strongly dependent on the cumulative cascade efficiency of the photogenerated carriers. Spatial heterojunctions are critical to directed charge transfer and, thus, attractive but still a challenge. Here, a spatially ternary titanium-defected TiO@carbon quantum dots@reduced graphene oxide (denoted as @CQDs@rGO) in one system is shown to demonstrate a cascade effect of charges and significant performances regarding the photocurrent, the apparent quantum yield, and photocatalysis such as H production from water splitting and CO reduction. A key aspect in the construction is the technologically irrational junction of Ti-vacancies and nanocarbons for the spatially inside-out heterojunction. The new "spatial heterojunctions" concept, characteristics, mechanism, and extension are proposed at an atomic-/nanoscale to clarify the generation of rational heterojunctions as well as the cascade electron transfer.

关键词： Ti-vacancy carbon dioxide reduction cascade effect seawater splitting spatial heterojunction

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Strong Solvent Coordination Effect Inducing Gradient Solid-Electrolyte-Interphase Formation for Highly Efficient Mg Plating/Stripping

SSRN

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SSRN 2023年

作者： Du, Yaoyao Chen, Yanmin Tan, Shuangshuang Chen, Jinlong Huang, Xueting Cui, Lianmeng Long, Juncai Wang, Zhongting Yao, Xuhui Shang, Bo Huang, Guangsheng Zhou, Xiaoyuan Li, Lingjie Wang, Jinfeng Pan, Fusheng School of Chemistry and Chemical Engineering Chongqing University Chongqing400044 China School of Materials Science and Engineering Chongqing University Chongqing400044 China National Engineering Research Center for Magnesium Alloys Chongqing University Chongqing400044 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan430070 China Advanced Technology Institute University of Surrey Guildford SurreyGU2 7XH United Kingdom College of Physics Center of Quantum Materials and Devices Chongqing University Chongqing401331 China

Developing simple Mg-salt electrolytes without chlorine-containing additives is vital for the technical viability of rechargeable magnesium batteries (RMBs). However, the formation of ion-blocking passivation layer on Mg anode in these electrolytes severely hinders the reversible Mg plating/stripping. Here, we successfully designed a highly efficient and chlorine-free Mg(SO3CF3)2/ether electrolyte by introducing 2-methoxyethylamine (MOEA) with a strongly nucleophilic amidogen (-NH2) donor to competing solvation coordination. The preferred decomposition of MOEA in MOEA-coordinated Mg-ion complex generates organic N-containing species in the inner layer, thus forming the gradient organic-inorganic SEI. This gradient SEI enables a fast interfacial Mg2+ migration and uniform Mg plating/stripping at 5 mA cm−2 with 5 mAh cm−2. The Mg(SO3CF3)2/ether/MOEA electrolyte exhibits high oxidation stability (3.5 V vs. Mg/Mg2+), high average Coulombic efficiency (99.3 %, 1000 cycles), excellent rate performance (low overpotential of 570 mV at 7.5 mA cm−2) and good compatibility with Mo6S8 cathode in coin (300 cycles at 1 C) and pouch cells, when using 50 μm Mg anode. Importantly, the relationships between solvation configuration, SEI chemistry and battery performance were successfully built for guiding the design of simple Mg-salt electrolytes in RMBs. © 2023, The Authors. All rights reserved.

关键词： Solvation

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Deformation Temperature Impacts on the Microstructure Evolution and Mechanical Properties of a Novel Medium-Heavy Alloy (Mha)

SSRN

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SSRN 2022年

作者： Xiong, Yi Shu, Kang-Hao Li, Yong Chen, Zheng-Ge Zha, Xiao-Qin He, Tian-Tian Han, Shun Wang, Chun-Xu School of Materials Science and Engineering Henan University of Science and Technology Luoyang471023 China Collaborative Innovation Center of New Nonferrous Metal Materials Advanced Processing Technology Jointly Established by the Ministry of Science and Technology Henan Luoyang471023 China Central Iron and Steel Research Institute Beijing100081 China State Key Laboratory of Laser Interaction with Matter Northwest Institute of Nuclear Technology Shaanxi Xi’an710024 China Luoyang Ship Material Research Institute Henan Luoyang471000 China

Medium-heavy alloys (MHAs) were rolled under different temperatures to characterize the microstructural evolution and mechanical properties by using optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, electron backscattered diffraction, tensile testing and microhardness testing. The results show that with an increase in the degree of deformation, the equiaxed grains are elongated along the rolling direction. A large number of slip bands are generated to coordinate intense plastic deformation, which leads to the formation of a fibrous texture. The sharp increase in dislocation density promotes significantly the dislocation interaction, which, in turn, refines the grain size of the MHAs to the nanometer level. Compared with the room-temperature rolling specimens, the cryorolling specimens underwent intense deformation. After 90% cryorolling deformation, the MHA grains were refined to 16.1 nm. The strength and hardness of the cryorolling specimens were significantly higher than those of the room-temperature rolling specimens, though the elongation was slightly lower. The fracture morphology of both specimens changed from ductile fracture (before deformation) to a mixed ductile–brittle fracture (after deformation). © 2022, The Authors. All rights reserved.

关键词： Cold rolling

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Electrically controlled nonvolatile switching of single-atom magnetism in a Dy@C84 single-molecule transistor

arXiv

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arXiv 2024年

作者： Wang, Feng Shen, Wangqiang Shui, Yuan Chen, Jun Wang, Huaiqiang Wang, Rui Qin, Yuyuan Wang, Xuefeng Wan, Jianguo Zhang, Minhao Lu, Xing Yang, Tao Song, Fengqi National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced Microstructures School of Physics Nanjing University Nanjing210093 China Institute of Atom Manufacturing Nanjing University Suzhou215163 China State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan430074 China School of Materials Science and Engineering Hefei University of Technology Hefei230009 China MOE Key Laboratory for Non-Equilibrium Synthesis and Modulation of Condensed Matter School of Physics Xi'an Jiaotong University Xi’an710049 China Center for Quantum Transport and Thermal Energy Science School of Physics and Technology Nanjing Normal University Nanjing210023 China School of Electronic Science and Engineering Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210023 China

Single-atom magnetism switching is a key technique towards the ultimate data storage density of computer hard disks and has been conceptually realized by leveraging the spin bistability of a magnetic atom under a scanning tunnelling microscope. However, it has rarely been applied to solid-state transistors, an advancement that would be highly desirable for enabling various applications. Here, we demonstrate realization of the electrically controlled Zeeman effect in Dy@C84 single-molecule transistors, thus revealing a transition in the magnetic moment from 3.8 μB to 5.1 μB for the ground-state GN at an electric field strength of 3 − 10 MV/cm. The consequent magnetoresistance significantly increases from 600% to 1100% at the resonant tunneling point. Density functional theory calculations further corroborate our realization of nonvolatile switching of single-atom magnetism, and the switching stability emanates from an energy barrier of 92 meV for atomic relaxation. These results highlight the potential of using endohedral metallofullerenes for high-temperature, high-stability, high-speed, and compact single-atom magnetic data storage. © 2024, CC BY.

关键词： Magnetic storage

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PAS Fabrication and Densification Mechanism of B-Al-Ti-C System Ceramics

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IOP Conference Series: materials Science and Engineering 2019年第1期678卷

作者： Guoqiang Luo Peng Fan Kejia Kang Yi Sun Jian Zhang Qiang Shen Lianmeng Zhang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China School of Mechanical and Electrical Engineering Henan University of Technology Zhengzhou 450000 China

In this paper, B-Al-Ti-C system ceramics were fabricated by plasma activated sintering(PAS) technique. The final sintered products consisted mainly of AlB12C2 and TiB2. The specimens could be densified at the temperature of 1460 °C~1600 °C, which is near 400 °C lower than the dense pure AlB12C2 and TiB2 ceramics. The sintered samples are nearly fully dense, and there are substantially no pores observed by observing the SEM photograph. The mechanism of low temperature densification and the phenomenon of varied specimens during sintering were explained in details in this study.

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Numerical Simulation of the Dynamic Performance of the Ceramic material Affected by Different Strain Rate and Porosity

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Journal of Physics: Conference Series 2013年第1期419卷

作者： Zhen Wang L S Liu H Mei X Lai P C Zhai D F Cao Department of Engineering Structure and Mechanics Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070 China

Ceramic materials are frequently used in protective armor applications for its low-density, high elastic modulus and high strength. It may be subject to different ballistic impacts in many situations, thus many studies have been carried out to explore the approach to improve the mechanical properties of the ceramic material. However, the materials manufactured in real world are full of defects, which would involve in variable fractures or damage. Therefore, the defects should be taken into account while the simulations are performed. In this paper, the dynamic properties of ceramic materials (Al2O3) affected by different strain rate (500–5000) and porosity (below 5%) are investigated. Foremost, the effect of strain rate was studied by using different load velocities. Then, compression simulations are performed by setting different porosities and random distribution of pores size and location in ceramic materials. Crack extensions and failure modes are observed to describe the dynamic mechanical behavior.

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synthesis and Characterization of Red Emissive Carbon Quantum Dots for Mb Degradation

SSRN

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SSRN 2024年

作者： Khojiev, Shokir Khojieva, Gulmira Chen, Dan Chen, Jun Mohamed, Hemdan S.H. Liu, Jing Li, Yu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology 122 Luoshi Road Hubei Wuhan430070 China School of International Education Wuhan University of Technology Wuhan430070 China Center for Advanced Technology under Agency for Innovative Development of the Republic of Uzbekistan The Ministry of Higher Education Science and Innovation University Street 3A Tashkent100174 Uzbekistan Department of Physical Chemistry Faculty of Chemistry National University of Uzbekistan University Street 4 Tashkent100174 Uzbekistan Physics Department Faculty of Science Fayoum University El Gomhoria Street Fayoum63514 Egypt

The one-step solvothermal method for the synthesis of R-CQDs by using 1,3-naphthalenediol was used. R-CQDs have an average particle size of 5nm with the functional groups, the presence of both D and G bands signifies successful construction of CQDs with sp2 core and sp3 hybridised matrix. R-CQDs exhibit a wide absorption peak at 512nm, while the emission intensity is highest at 610nm. R-CQDs show high photocatalytic performance for the photodegradation efficiency of 96% in 180 min. Its photocatalytic degradation rate constant was as 0.0167 min−1. R-CQDs demonstrated uniformly performance, making them superior photocatalyst in a variety of pH media. © 2024, The Authors. All rights reserved.

关键词： Degradation

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The Application of Ti/Al2O3 Composite in W-Mo-Al System Wave Impedance Graded Flier-plate

引用

Journal of Physics: Conference Series 2013年第1期419卷

作者： Z Wang S Feng G P Shi Q Shen L M Zhang School of Materials Science and Engineering University of Jinan Jinan 250022 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Ti/Al2O3 composite of different components were prepared by Spark Plasma Sintering technique, mechanical and acoustical properties of Ti/Al2O3 composite were analyzed, weldability of Ti/Al2O3 composite with Mo and Al was also studied. The results indicate that 38.5vol%Ti/Al2O3 composite has good mechanical performance with relative density >99.20%, bending strength 897MPa, fracture toughness 17.38 MPam1/2 and micro-hardness 17.13GPa. The wave impedance of the composite was between which of Mo and Al, and the 38.5vol% Ti/Al2O3 welded well with Mo and Ti. These demonstrate that 38.5vol%Ti/Al2O3 composite could serve as one of interlayer materials in W-Mo-Al system graded flier-plate.

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Numerical simulation of two-dimensional photonic crystal with FDTD method

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2008年第3期30卷 5-7页

作者： Zhou, Jian Jiang, Hong-Zhou Zhang, Lin Wang, Lin Zeng, Chun-Nian Chen, Ji State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China School of Information Engineering Wuhan University of Technology Wuhan 430070 China School of Automotive Engineering Wuhan University of Technology Wuhan 430070 China Department of Electrical and Computer Engineering University of Houston Houston United States

Based on the theory of photonic crystal and its characteristic, which was known as photonic band gap (PBG), the finite-difference time-domain (FDTD) method, including absorbing boundary condition and periodic boundary condition, was used to simulate transmission characteristic of two-dimensional photonic crystal, which has periodic Al2O3 cylinder array structure. Incident wave was presumed as s-polarized wave. In two incident angles which were 0° and 30°, electric field, phase and transmissivity in the range of 1-30 μm were calculated. Numerical simulation results showed that PBG of photonic crystal existed in the range 12-18 μm (infrared waveband), and it may be used to develop infrared wave-guide.

关键词： FDTD Periodic structure Photonic band gap Photonic crystal

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