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Dynamic surface restructuring of nanoporous Cu_(2-x)Se for efficient CO_(2) electroreduction into methanol

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Journal of Energy Chemistry 2022年第8期31卷 514-520,I0014页

作者： Xin Lin Xunlin Liu Yang Zhao Jiao Lan Kang Jiang Zhixiao Liu Feng Xie Yongwen Tan College of Materials Science and Engineering State Key Laboratory of Advanced Design and Manufacturing for Vehicle BodyHunan UniversityChangsha 410082HunanChina College of Materials Science and Engineering Hunan UniversityChangsha 410082HunanChina

The nanoporous Cu_(2-x)Se with Cu(Se-5%)surface catalysts were prepared through in situ dynamic restructuring strategy during the electrochemical process,which achieves highly selective electrochemical CO_(2) reduction to *** situ and quasi-operando spectroscopic results provide a deep insight into the catalytic active centres of reconstructed heterogeneous catalysts for CO_(2) electroreduction.

关键词： Surface restructuring Nanoporous Cu_(2-x)Se Carbon dioxide reduction Methanol

Analysis and optimization of performance parameters of the^(220)Rn chamber in flow-field mode using computational fluid dynamics method

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Nuclear Science and Techniques 2024年第10期35卷 70-85页

作者： Shao-Hua Hu Yong-Jun Ye Zheng-Zhong He De-Tao Xiao Xiang-Yu Xu Jian-Kai Wang Qing-Zhi Zhou School of Nuclear Science and Technology University of South ChinaHengyang 421001China School of Resources Environment and Safety Engineering University of South ChinaHengyang 421001China

The impact of the radiation dose produced by^(222)Rn/^(220)Rn and its progeny on human health has garnered increasing interest in the nuclear research *** establishment of robust,regulatory,and competent^(220)Rn chambers is crucial for accurately measuring radioactivity ***,studying the uniformity of the^(220)Rn progeny through experimental methods is challenging,because measuring the concentration of^(220)Rn and its progeny in multiple spatial locations simultaneously and in real time using experimental methods is ***,achieving precise control of the concentration of^(220)Rn and its progeny as well as the reliable sampling of the progeny pose significant *** solve this problem,this study uses computational fluid dynamics to obtain the flow-field data of the^(220)Rn chamber under different wind speeds and progenyreplenishment *** analysis of the concentration distribution of the progeny and quantitative analysis of the progeny concentration and uniformity of the progeny concentration are *** research findings indicated that the progeny concentration level is primarily influenced by wind speed and the progeny-complement *** speed also plays a crucial role in determining progeny concentration uniformity,whereas the progeny-complement rate has minimal impact on *** ensure the accuracy of^(220)Rn progeny concentration sampling,we propose a methodology for selecting an appropriate sampling area based on varying progeny *** study holds immense importance for enhancing the regulation and measurement standards of^(220)Rn and its progeny.

关键词： Thoron Progeny Regulatory CFD simulation

Weakening behavior of waterproof performance in joints of shield tunnels under adjacent constructions

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Frontiers of Structural and Civil Engineering 2023年第6期17卷 884-900页

作者： Huai-Na WU Lei LIU Yuan LIU Ren-Peng CHEN Hai-Lin WANG Shi-Qiang RUAN Meng FAN Research Center of Underground Space Advanced Technology Hunan UniversityChangsha410082China Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education Hunan UniversityChangsha410082China Department of Civil Engineering Hunan UniversityChangsha410082China hunan Provincial Communications Planning Survey&Design Institute Co.Ltd.Changsha410082China

Groundwater leakage in shield tunnels poses a threat to the safety and durability of tunnel structures. Disturbance of adjacent constructions during the operation of shield tunnels frequently occurs in china, leading to deformation of tunnel lining and leakage in joints. Understanding the impact of adjacent constructions on the waterproofing performance of the lining is critical for the protection of shield tunnels. In this study, the weakening behavior of waterproof performance was investigated in the joints of shield tunnels under transverse deformation induced by adjacent construction. First, the relationship between the joint opening and transverse deformation under three typical adjacent constructions (upper loading, upper excavation, and side excavation) was investigated via elaborate numerical simulations. Subsequently, the evolution of the waterproof performance of a common gasket with a joint opening was examined by establishing a coupled Eulerian-Lagrangian model of joint seepage, and a formula describing the relationship between waterproof performance and joint opening was proposed. Finally, the weakening law of waterproofing performance was investigated based on the results of the aforementioned studies. It was determined that the joints with the greatest decline in waterproof performance were located at the tunnel shoulder in the upper loading case, tunnel crown in the upper excavation case, and tunnel shoulder in the side excavation case. When the waterproof performance of these joints decreased to 50% and 30%, the transverse deformations were 60 and 90 mm under upper loading, 90 and 140 mm under upper excavation, and 45 and 70 mm under side excavation, respectively. The results provide a straightforward reference for setting a controlled deformation standard considering the waterproof performance.

关键词： shield tunnel waterproof performance horizontal transverse deformation joint opening weakenning behavior

Flow softening and dynamic recrystallization behavior of a Mg-Gd-Y-Nd-Zr alloy under elevated temperature compressions

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Journal of Magnesium and Alloys 2023年第8期11卷 2891-2900页

作者： Yiping WU Yuzhen JIA Sha Zhang Yu Liu Hanqing Xiong Gang Chen Department of Mechanical and Electrical Engineering Changsha UniversityChangsha 410003China Bichamp Cutting Technology(hunan)Co. LtdChangsha 410200China College of Material Science and Engineering Hunan UniversityChangsha Hunan 410082China

Flow softening behavior of a homogenized Mg-7Gd-4Y-1Nd-0.5Zr alloy under compression to a final strain of∼1.8 at elevated temperatures of 450∼550℃ and a constant strain rate of 2s^(−1) has been investigated by optical microscopy,scanning electron microscopy,electron back-scattered diffraction and transmission electron *** results show that true stress first rises to the peak point and then drops to the bottom value and increases again with further increasing strain at each *** dynamic recrystallization(DRX)and continuous DRX contribute to the formation of new fine grains at temperatures 450∼475℃ when the restoration is caused by both DRX and texture change due to extension twinning,resulting in the larger softening degrees compared with the softening effects owing to continuous DRX and discontinuous DRX at 500∼550℃ when twinning activation is suppressed.500℃ is the transition temperature denoting a significant decline in the contribution of twinning and TDRX to the strain with increasing *** cuboid-shape phase exists in both homogenized and compressed samples,while the compositions are varied.

关键词： Mg-Gd-Y alloy Elevated temperature compression Flow softening Dynamic recrystallization

Free-standing phosphorous-doped molybdenum nitride in 3D carbon nanosheet towards hydrogen evolution at all pH values

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Journal of Energy Chemistry 2020年第11期29卷 44-51页

作者： Qiyou Wang Yan Zhang Wenpeng Ni Yi Zhang Tian Sun Jiaheng Zhang Junfei Duan Yang Gao Shiguo Zhang College of Materials Science and Engineering Hunan Province Key Laboratory for Advanced Carbon Materials and Applied TechnologyHunan UniversityChangsha 410082HunanChina School of Materials Science and Engineering Harbin Institute of TechnologyShenzhen 518055GuangdongChina School of Materials Science and Engineering Changsha University of Science and TechnologyChangsha 410004HunanChina

Highly efficient electrocatalysts towards hydrogen evolution reaction(HER) with large current density at all-pH values are critical for the sustainable hydrogen production. Herein, we report a free-standing HER electrode, phosphorous-doped molybdenum nitride nanoparticles embedded in 3-dimentional carbon nanosheet matrix(P-Mo2N-CNS) fabricated via one-step carbonization and in-situ formation. The asprepared catalyst shows free-standing architecture with interconnected porous microstructure. P-doped Mo2N nanoparticles with an average diameter of 4.4 nm are well embedded in the 3-dimentional vertical carbon nanosheets matrix. Remarkable electrocatalytic HER performance is observed in alkaline, neutral and acidic media at large current densities. The overpotential of P-Mo2N-CNS to drive a current density of 100 mA cm-2 in 0.5 M H2SO4 and 1.0 M PBS is only 181 and 221 mV, respectively. In particular, the current density reaches up to 1000 mA cm-2 at a low overpotential of 256 mV in 1.0 M KOH, much better than that of the commercial Pt/C catalyst. Density functional theory calculations suggest the optimized H sorption kinetics on Mo2N after P doping, elucidating the superior activity.

关键词： Hydrogen evolution reaction Molybdenum nitride Heteroatoms doping Free-standing catalyst DFT calculations

Inorganic Colloidal Electrolyte for Highly Robust Zinc‑Ion Batteries

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Nano-Micro Letters 2021年第4期13卷 247-258页

作者： Jiawei Gao Xuesong Xie Shuquan Liang Bingan Lu Jiang Zhou School of Materials Science and Engineering Central South UniversityChangsha 410083People’s Republic of China School of Physics and Electronics Hunan UniversityChangsha 410082People’s Republic of China Key Laboratory of Electronic Packaging and Advanced Functional Materials of hunan province Central South UniversityChangsha 410083People’s Republic of China

Zinc-ion batteries(ZIBs)is a promising electrical energy storage candidate due to its eco-friendliness,low cost,and intrinsic safety,but on the cathode the element dissolution and the formation of irreversible products,and on the anode the growth of dendrite as well as irreversible products hinder its practical ***,we propose a new type of the inorganic highly concentrated colloidal electrolytes(HCCE)for ZIBs promoting simultaneous robust protection of both cathode/anode leading to an effective suppression of element dissolution,dendrite,and irreversible products *** new HCCE has high Zn^(2+)ion transference number(0.64)endowed by the limitation of SO4^(2−),the competitive ion conductivity(1.1×10^(–2) S cm^(−1))and Zn2+ion diffusion enabled by the uniform pore distribution(3.6 nm)and the limited free *** Zn/HCCE/α-MnO2 cells exhibit high durability under both high and low current densities,which is almost 100%capacity retention at 200 mA g^(−1) after 400 cycles(290 mAh g^(−1))and 89%capacity retention under 500 mA g^(−1) after 1000 cycles(212 mAh g^(−1)).Considering material sustainability and batteries’high performances,the colloidal electrolyte may provide a feasible substitute beyond the liquid and all-solid-state electrolyte of ZIBs.

关键词： Zn-ion battery Palygorskite Inorganic Colloidal electrolyte Cycle stability

Semi-closed synthesis of nitrogen and oxygen Co-doped mesoporous carbon for selective aqueous oxidation

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Green Energy & Environment 2022年第1期7卷 43-52页

作者： Chen Xing Daihui Yang Yan Zhang Tian Sun Junfei Duan Hussein A.Younus Shiguo Zhang College of Materials Science and Engineering Hunan Province Key Laboratory for Advanced Carbon Materials and Applied TechnologyHunan UniversityChangsha410082China School of Materials Science and Engineering Changsha University of Science and TechnologyChangsha410004China Chemistry Department Faculty of ScienceFayoum UniversityFayoum63514Egypt

Heteroatom-doped meso/micro-porous carbon materials are conventionally produced by harsh carbonization under an inert atmosphere involving specific precursors,hard/soft templates,and heteroatom-containing ***,we report a facile synthesis of N and O co-doped meso/micro-porous carbon(NOMC)by template-free carbonization of a small-molecule precursor in a semi-closed *** semi-closed carbonizaiton process yields hydrophilic NOMCs with large surface area in a high *** porous structure as well as the elemental composition of NOMCs can be modulated by changing the holding time at a particular *** as metal-free heterogeneous catalysts can selectively oxidize benzyl alcohol and its derivatives into aldehydes/ketones with>85%conversion in aqueous solution,which is much higher than that of the control sample obtained in tube furnace(21%conversion),mainly due to their high N content,high percentage of pyridinic N,and large surface *** presence of O-containing moieties also helps to improve the hydrophilicity and dispersion ability of catalysts and thus facilitates the mass transfer process during aqueous *** NOMC catalysts also dispayed excellent activity for a wide range of substrates with a selectivity of>99%.

关键词： Semi-closed carbonization Nitrogen and oxygen doping Mesoporous carbon Metal-free catalyst Selective aqueous oxidation

Relationship among the secretion of extracellular polymeric substances, heat resistance, and bioleaching ability of Metallosphaera sedula

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International Journal of Minerals,Metallurgy and Materials 2019年第12期26卷 1504-1511页

作者： Run-lan Yu Zhen-hua Liu Zhao-jing Yu Xue-ling Wu Li Shen Yuan-dong Liu Jiao-kun Li Wen-qing Qin Guan-zhou Qiu Wei-min Zeng School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Key Laboratory of Biometallurgy of Ministry of Education Central South UniversityChangsha 410083China

This paper describes the investigation of the secretion of extracellular polymeric substances(EPS)by an extremely thermoacidophilic archaea,Metallosphaera sedula(***),during the bioleaching of pyrite under different temperatures and discusses the relationship among the EPS secretion,its heat resistance,and its ability to bioleach *** investigation results indicate that the amount of extracellular proteins is significantly higher than the amount of extracellular polysaccharides in the extracted EPS whether free cells or attached cells;these results are quite different from the behavior of mesophilic Acidithiobacillus *** the growth of *** is inhibited at 80℃,the bioleaching ability of *** is only slightly lower than that at the optimum growth temperature of 72℃ because of the heat resistance mechanism based on EPS *** secretion of more extracellular proteins is an important heat resistance mechanism of ***.

关键词： bioleaching extracellular polymeric substances(EPS) heat resistance Metallosphaera sedula

Ultrathin organic polymer with p-πconjugated structure for simultaneous photocatalytic disulfide bond generation and CO_(2)reduction

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Journal of Energy Chemistry 2023年第1期76卷 639-647,I0016页

作者： Linquan Hou Zhunyun Tang Guojiang Mao Shiheng Yin Bei Long Tao Ouyang Guo-Jun Deng Atif Ali Ting Song Key Laboratory for Green Organic Synthesis and Application of hunan province Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of EducationCollege of ChemistryXiangtan UniversityXiangtan 411105HunanChina hunan Key Laboratory for Micro-Nano Energy Materials and Device School of Physics and OptoelectronicsXiangtan UniversityXiangtan 411105HunanChina School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiang 453007HenanChina Analytical and Testing Center South China University of TechnologyGuangzhou 510640GuangdongChina Department of Chemistry and State Key Laboratory of Synthetic Chemistry The University of Hong KongPokfulam RoadHong Kong 999077China

Combining photocatalytic organic reactions with CO_(2)reduction is an efficient solar energy utilization mode,but it is still limited by the organic species that can be matched and the low ***,ultrathin organic polymer with p-πconjugated structure(TPP)was rationally designed and prepared,and showed a high yield of CO(15.2 mmol g^(-1))and conversion of SAS coupled products(100%),far exceeding the organic polymer with P=O *** enhanced photoredox activity of TPP is ascribed to the orbital interaction between the p-orbital on phosphorus and theπ-orbitals of aromatic,which can accelerate the photoinduced charge carrier separation and improve the CO_(2)adsorption *** can also be used for the dehydrocoupling of various benzyl mercaptans to the corresponding SAS bond *** work provides a new concept for the efficient synthesis of disulfide bonds combined with CO_(2)reduction in a photoreaction system.

关键词： Photocatalytic coupled reaction Disulfide bond CO_(2)reduction High activity Organic polymer