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Electron transfer kinetics in CdS/Pt heterojunction photocatalyst during water splitting

Chinese Journal of Catalysis 2022年第10期43卷 2530-2538页

作者： Jianjun Zhang Gaoyuan Yang Bowen He Bei Cheng Youji Li Guijie Liang Linxi Wang Laboratory of Solar Fuel Faculty of Materials Science and ChemistryChina University of GeosciencesWuhan 430074HubeiChina Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices Hubei University of Arts and ScienceXiangyang 441053HubeiChina State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070HubeiChina College of chemistry and Chemical engineering Jishou UniversityJishou 416000HunanChina

Noble metal cocatalysts have shown great potential in boosting the performance of CdS in photocatalytic water ***,the mechanism and kinetics of electron transfer in noble-metal-decorated CdS during practical hydrogen evolution is not clearly ***,Pt-nanoparticle-decorated CdS nanorods(CdS/Pt)are utilized as the model system to analyze the electron transfer kinetics in CdS/Pt *** femtosecond transient absorption spectroscopy,three dominating exciton quenching pathways are observed and assigned to the trapping of photogenerated electrons at shallow states,recombination of free electrons and trapped holes,and radiative recombination of locally photogenerated electron-hole *** introduction of Pt cocatalyst can release the electrons trapped at the shallow states and construct an ultrafast electron transfer tunnel at the CdS/Pt *** CdS/Pt is dispersed in acetonitrile,the lifetime and rate for interfacial electron transfer are respectively calculated to be~5.5 ps and~3.5×10^(10) s^(−1).The CdS/Pt is again dispersed in water to simulate photocatalytic water *** lifetime of the interfacial electron transfer decreases to~5.1 ps and the electron transfer rate increases to~4.9×10^(10) s^(−1),confirming that Pt nanoparticles serve as the main active sites of hydrogen *** work reveals the role of Pt cocatalysts in enhancing the photocatalytic performance of CdS from the perspective of electron transfer kinetics.

关键词： Femtosecond transient absorption spectroscopy Photocatalytic water splitting CdS Electron transfer kinetics Trap state

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Reply to Comments on “Efficient full-path optical calculation of scalar and vector diffraction using the Bluestein method”

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Light(Science & Applications) 2021年第1期10卷 3-4页

作者： Yanlei Hu Zhongyu Wang Xuewen Wang Shengyun Ji Chenchu Zhang Jiawen Li Wulin Zhu Dong Wu Jiaru Chu CAS Key Laboratory of Mechanical Behavior and Design of Materials Key Laboratory of Precision Scientific Instrum entation of Anhui Higher Education InstitutesDepartm ent of Precision Machinery and Precision InstrumentationUniversity of Science and Techno logy of China230026 HefeiChina Departm ent of Mechanical Engineering and Departm ent of Civil and Environm ental Engineering Massachusetts Institute of TechnologyCam bridgeMA 02139USA State Key Laboratory of Advanced Technology for Materials Synthesis and Processing International School of Materials Science and EngineeringWuhan University of Technology430070 WuhanChina Institute of Industry and Equipment Technology Hefei Uniersity of Technology230009 HefeiChina

Dear Editor,In *** present an efficient full-path optical calculation by using the Bluestein method.A real optical apparatus for laser processing,imaging,or optical tweezing normally involves diverse optical lenses with different physical and numerical apertures(NA).In such applications,the optical path is usually tortuous and *** assist in the design,evaluation,and alignment of optical instruments,it is advantageous to retrieve the optical field in an arbitrary position along the entire optical path,which is termed the full-path calculation in our paper,with sufficient accuracy and *** particular,high flexibility is required to accommodate the mismatch between optical apertures of different components in the optical *** present a fullpath optical calculation method by adopting the Bluestein method to address this realistic demand.

关键词： optical calculation method

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Preparation and Investigation of Zro2-Based Thermal Control Coatings Doped with Mgo

SSRN

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SSRN 2023年

作者： Zeng, Xian Wang, Youyuan Wang, Meng Wang, Zheng Long, Ziqiang Li, Bei Cao, Qian Cheng, Xudong School of Materials Science and Engineering Wuhan University of Technology Wuhan430070 China Research Center for Materials Genome Engineering Wuhan University of Technology Wuhan430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan430070 China

In this study, MgO doped ZrO2 thermal control coatings were prepared using atmospheric plasma spraying technology. The phase composition, microstructure, optical properties of the coatings were characterized. The results showed that all the coatings possessed an obvious laminar structure. With the increase of MgO doping content, the chemicals of the coatings showed a trend of transition from monoclinic to cubic phase. Moreover, the solar absorptance (αs) effectively decreased, while the hemispherical emissivity (ΕH) increased. When the doping content reached 20 mol%, the ΕH/αs obtained a minimum value of 0.475, where the αs and ΕH was 0.399and 0.8395 correspondingly. Though the impurity levels introduced by the oxygen vacancies were beneficial to enhancing the intrinsic absorption in the 0.3~0.75 μm wave band, the decrease of free carrier concentration attenuated the free carrier absorption and weakened the emission property in the 0.75~7 μm wave band, resulting in a declining of αs. The enhancement of the hemispherical emissivity ΕH was attributed to the lattice distortion, which strengthen the radiation capability in the 7~25 μm wave band. © 2023, The Authors. All rights reserved.

关键词： Magnesia

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Elemental Distribution and Site Occupancy in a Co-Ni-Al-Ti-Ta-W Superalloy

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SSRN 2024年

作者： Zhang, Jiachen Lu, Wenjie Lu, Fan Na, Qingze Yan, Pan Su, Haijun Zhang, Guojun School of Materials Science and Engineering Xi'an University of Technology Xi’an710048 China State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi’an710072 China State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing100083 China

γ′-precipitate strengthened cobalt-based superalloys show promise for higher temperature-capability over nickel-based superalloys due to higher melting temperatures. This study investigates a multicomponent CoNi-based superalloy with composition 54Co-30Ni-9Al-1Ta-4Ti-2W (at.%) in terms of elemental partitioning and site occupancy. APT reveals preferential partitioning of Ni, Al, Ti, Ta and W to the γ′-precipitate and Co to the γ-matrix. HAADF-STEM and EDS along the [001] zone axis of γ′-precipitate with L12 structure indicate that Co, Ni substitute on A-sites, while Al, Ti, Ta, W prefer the B-sites. DFT calculations further confirm the results of partitioning behaviors and site preferences. Clarifying elemental partitioning and site occupancy provides insights into alloy design principles for advanced CoNi-based superalloys. © 2024, The Authors. All rights reserved.

关键词： Superalloys

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Effect of Y2O3-Al2O3 sintering additive content on the properties of porous Si3N4 ceramics prepared by digital light processing using Polymethyl methacrylate as pore-forming agent

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Ceramics International 2025年

作者： Wu, Ya-Ru Huang, Hai-Lu Tian, Chong Wu, Jia-Min Liu, Chun-Lei Guo, Lin Cai, Wei-Hao Yang, Ling-Hao Liu, Zhi-Wei Zhang, Yang-Ze Luo, Zhi-Cong Su, Sen Shi, Yu-Sheng State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan430074 China Engineering Research Center of Ceramic Materials for Additive Manufacturing Ministry of Education Wuhan430074 China Wenzhou Key Laboratory of Microwave Communication Materials and Devices Wenzhou Advanced Manufacturing Institute of HUST Wenzhou325035 China

Porous Si3N4 ceramics have been widely used in aerospace and military industry due to their excellent mechanical properties. Digital light processing (DLP) technology offers an effective route to prepare porous Si3N4 ceramics. In this paper, porous Si3N4 ceramics were successfully fabricated by DLP technology using Polymethyl methacrylate (PMMA) as pore-forming agent, and the effects of the sintering additive (Y2O3-Al2O3) content on the properties of Si3N4 ceramic slurry, green bodies and sintered parts were systematically studied. With the increase of sintering additive content from 2 wt% to 14 wt%, the viscosity of the Si3N4 slurry decreased and the cure depth of that increased. It was found that Y2O3 in sintering additives could induce the growth of β-Si3N4 grain and the fracture mode of Si3N4 ceramics changed from transgranular fracture to intergranular fracture gradually. Additionally, the porosity of porous Si3N4 ceramics first decreased and then increased, while the bulk density, flexural strength of the sintered samples first increased and then decreased with the increase of the sintering additive content. When the content of Y2O3-Al2O3 sintering additives was 10 wt%, the flexural strength of the Si3N4 ceramics reached the maximum value of 459.38 MPa. This research is of great significance for the mechanical property improvement of porous Si3N4 ceramics prepared by DLP. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Machinability

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Microstructure and mechanical properties of extruded Mg-Sn alloys with a heterogeneous grain structure

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Journal of Magnesium and Alloys 2024年

作者： Tong, Lin Jiang, Jing Bi, Guangli Li, Yuandong Chen, Tijun Zhang, Xiaoru Fang, Daqing State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of Technology Lanzhou730050 China School of Material Science and Engineering Lanzhou University of Technology Lanzhou730050 China State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an710049 China

The high-strength Mg-7Sn alloys (wt.%) with a heterogeneous grain structure were prepared by low-temperature extrusion (230 °C) with the extrusion ratio of 9:1 (9E230) and 17:1 (17E230). The two extruded alloys contained fine dynamic recrystallization (DRX) grains (FG) and coarse unDRX grains (CG). The difference in deformability between CG and FG leads to the formation of heterogeneous grain structure. The average grain size and basal texture intensities increased while the volume fraction of CG decreased with increasing extrusion ratio. Tensile testing results indicated that the extruded 17E230 alloy exhibited higher tensile strengths than 9E230 alloy, whose tensile yield strength (σ0.2), ultimate tensile strengths (σb), and elongation to failure (Εf) were 231.1 MPa, 319.5MPa, and 12.54 % respectively. The high tensile strengths of the extruded alloy mainly originated from grain refinement, texture strengthening, precipitation strengthening from a great number of nano-scale Mg2Sn phases, solid solution strengthening and hetero-deformation induced (HDI) strengthening, while the good ductility of the alloy was also mainly attributed to grain refinement, activation of the non-basal slip systems and HDI hardening. © 2024

关键词： Tensile strength

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Design and Strengthening Mechanism of Silver-Carbon Synergistic Reinforced Al Matrix Composites

SSRN

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SSRN 2023年

作者： Li, Junguo Yang, Xuebin Li, Peibo Zhang, Yang Luo, Guoqiang Shen, Qiang Sun, Yi State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan430070 China Chaozhou Branch of Chemistry and Chemical Engineering Guangdong Laboratory Chaozhou521000 China Hubei Longzhong Laboratory Hubei Xiangyang441000 China

Owing to inadequate interface contact between carbon and aluminum, enhancing the Al/C interface is crucial for the fabrication of high-performance Al matrix composites. This study selected polyvinyl butyral (PVB) with excellent dispersion properties as the carbon source. Simultaneously introducing silver to achieve synergistic reinforcement between silver and carbon in Al matrix composites, offering a novel reinforcement approach for Al matrix composites. The Al-16Ag-C composite is fabricated through the in-situ pyrolysis of PVB followed by hot pressing sintering. Subsequently, the effect of temperature on the microstructural evolution and mechanical properties of the composite is investigated. Microstructural characterization demonstrates the formation of two alloy phases, namely Ag2Al and Al4C3, within the Al-16Ag-C composite. The alloy phases, distributed at the grain boundaries, enhance the material’s strength by impeding dislocation motion, increasing dislocation density within the matrix, and limiting grain growth. The Al-16Ag-C composite, sintered at 630 °C, exhibits a remarkable ultimate tensile strength of 481 MPa and an elongation of 22.25%, representing a significant enhancement compared to pure Al. © 2023, The Authors. All rights reserved.

关键词： Polyvinyl butyral

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Towards intelligent design optimization: Progress and challenge of design optimization theories and technologies for plastic forming

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Chinese Journal of Aeronautics 2021年第2期34卷 104-123页

作者： Heng LI Jingchao YANG Guangyao CHEN Xin LIU Zhao ZHANG Guangjun LI Wenhui LIU State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Poly technical UniversityXi'an 710072China Chengdu Aircraft Industry(Group)Corporation Ltd. Chengdu 610092China High Temperature Wear Resistant Materials and Preparation Technology of Hunan Province National Defence Science and Technology Laboratory Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and ConversionSchool of Materials Science and EngineeringHunan University of Science and TechnologyXiangtan 411201China

Plastic forming is one of enabling and fundamental technologies in advanced manufacturing chains. Design optimization is a critical way to improve the performance of the forming system, exploit the advantages of high productivity, high product quality, low production cost and short time to market and develop precise, accurate, green, and intelligent(smart) plastic forming technology. However, plastic forming is quite complicated, relating to multi-physics field coupling,multi-factor influence, multi-defect constraint, and triple nonlinear, etc., and the design optimization for plastic forming involves multi-objective, multi-parameter, multi-constraint, nonlinear,high-dimensionality, non-continuity, time-varying, and uncertainty, etc. Therefore, how to achieve accurate and efficient design optimization of products, equipment, tools/dies, and processing as well as materials characterization has always been the research frontier and focus in the field of engineering and manufacturing. In recent years, with the rapid development of computing science, data science and internet of things(Io T), the theories and technologies of design optimization have attracted more and more attention, and developed rapidly in forming process. Accordingly, this paper first introduced the framework of design optimization for plastic forming. Then, focusing on the key problems of design optimization, such as numerical model and optimization algorithm,this paper summarized the research progress on the development and application of the theories and technologies about design optimization in forming process, including deterministic and uncertain optimization. Moreover, the applicability of various modeling methods and optimization algorithms was elaborated in solving the design optimization problems of plastic forming. Finally, considering the development trends of forming technology, this paper discusses some challenges of design optimization that may need to be solved and faced in forming pr

关键词： advanced manufacturing Design optimization Deterministic optimization(DOP) Intelligent design optimization(IDO) Plastic forming Uncertain optimization(UOP)

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Self-Adaptive Control System for Additive Manufacturing Using Double Electrode Micro Plasma Arc Welding

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Chinese Journal of Mechanical Engineering 2021年第3期34卷 285-298页

作者： Nan Li Ding Fan Jiankang Huang Shurong Yu Wen Yuan Miaomiao Han School of Materials Science and Engineering Lanzhou University of TechnologyLanzhou 730050China State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of TechnologyLanzhou 730050China School of Mechanical and Electrical Engineering Lanzhou University of TechnologyLanzhou 730050China

Wire arc additive manufacturing(WAAM)has been investigated to deposit large-scale metal parts due to its high deposition efficiency and low material ***,in the process of automatically manufacturing the high-quality metal parts by WAAM,several problems about the heat build-up,the deposit-path optimization,and the stability of the process parameters need to be well *** overcome these issues,a new WAAM method based on the double electrode micro plasma arc welding(DE-MPAW)was *** circuit principles of different metal-transfer models in the DE-MPAW deposition process were analyzed *** effects between the parameters,wire feed rate and torch stand-off distance,in the process of WAAM were investigated *** addition,a real-time DE-MPAW control system was developed to optimize and stabilize the deposition process by self-adaptively changing the wire feed rate and torch stand-off ***,a series of tests were performed to evaluate the control system’s *** results show that the capability against interferences in the process of WAAM has been enhanced by this self-adaptive adjustment ***,the deposition paths about the metal part’s layer heights in WAAM are ***,the appearance of the WAAM-deposited metal layers is also improved with the use of the control system.

关键词： Double electrode microplasma arc welding Additive manufacturing Wire feed rate Torch stand-off distance Self-adaptive adjustment

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Influence of rotation tool-induced friction regime transformation on heat generation and material flow during friction stir welding: a computational fluid dynamics study

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The International Journal of advanced Manufacturing technology 2025年第1期139卷 519-534页

作者： Qiao, Junnan Shi, Qingyu Chen, Shujun Yang, Chengle Han, Yang Chen, Gaoqiang State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical Engineering Tsinghua University Beijing China Key Laboratory for Advanced Materials Processing Technology Ministry of Education Beijing China CRRC Technology Innovation (Beijing) Co. Ltd Beijing China Engineering Research Center of Advanced Manufacturing Technology for Automotive Components Ministry of Education Beijing University of Technology Beijing China

This study employs computational fluid dynamics (CFD) simulations, incorporating an advanced shear stress boundary condition at the tool-workpiece interface, to investigate the influence of tool rotation speed on the interface friction regime, material flow, and heat generation. Experimental measurements of the temperature cycle curve, the shape of plastic deformation zone, and the deposition position of marking material validate the simulation accuracy. The simulation results indicate a transition in the friction mechanism from sliding to sticking as the tool rotation speed increases. At higher tool rotation speeds, the total heat generation depends on the strength of the material itself. Therefore, tool rotation speeds in a certain range will not significantly affect the heat generation. Regardless of the tool rotation speed, the material flow from the front of the metal through the pin’s influence zone consistently follows a straight-through pattern. However, at higher tool rotation speeds, some materials flowing through the shoulder’s influence zone from the front of the metal rotate around the tool multiple times, exhibiting a multi-turn flow pattern. The deposition position of marking materials also changes from a symmetric to an asymmetric distribution when the friction regime transitions from sliding to sticking.

关键词： Friction regime Friction stir welding Heat generation Material flow Tool rotation speed

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