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一种高效稳定的大电流密度产氢电催化剂

Science Bulletin 2020年第2期65卷 123-130,87-88页

作者：薛森刘志博马超群成会明任文才 School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of Chin1Shenyang 110016China Tsinghua-Berkeley Shenzhen Institute(TBSI) Tsinghua UniversityShenzhen 518055China

电解水制氢具有工艺简单、原料来源广泛、无污染、氢气纯度高等优点,是最具发展前景的制氢技术之一.然而电解水制氢存在的最大问题是析氢析氧过程能耗过高,需要添加催化剂降低反应能垒.目前,电催化产氢性能最好的材料依然是价格昂贵且... 详细信息

电解水制氢具有工艺简单、原料来源广泛、无污染、氢气纯度高等优点,是最具发展前景的制氢技术之一.然而电解水制氢存在的最大问题是析氢析氧过程能耗过高,需要添加催化剂降低反应能垒.目前,电催化产氢性能最好的材料依然是价格昂贵且储量有限的贵金属铂基催化剂.发展高效稳定的大电流密度制氢非贵金属催化剂,对于氢气的规模化制备和商业化应用意义重大.本工作采用三维导电泡沫镍为自支撑电极材料,引入钼源和硫源构建高活性催化析氢Mo-Ni-S体系.通过水热反应和退火处理,在泡沫镍基底上制备得到了具有高担载量、细长浓密的Mo S2/Ni3S2同轴异质结构纳米线.催化剂结构设计方面,在水热反应过程中创新性地引入表面活性剂(P123),调控催化剂形貌,增加了活性位点数目.在组分调控方面,通过后期退火处理去除低活性物相,增强了催化性能.基于以上结构和组分设计调控,该催化剂在碱性体系下具有优异的大电流密度催化产氢性能,仅需较低过电势便可获得较高的电流密度,同时具有优异的大电流密度产氢稳定性,其电催化产氢性能超过了已报道的众多催化剂.

关键词： MoS2/Ni3S2 nanowire Co-axial heterostructure Large Current density HER Alkaline electrolyte

Nonlinear optics in the electron-hole continuum in 2D semiconductors:two-photon transition, second harmonic generation and valley Current injection

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Science Bulletin 2019年第15期64卷 1036-1043页

作者： Pu Gong Hongyi Yu Yong Wang Wang Yao Department of Physics and Center of Theoretical and Computational Physics The University of Hong KongHong KongChina School of Physics Nankai UniversityTianjin 300350China

We investigate two-photon transitions to the electron-hole scattering continuum in monolayer transition-metal dichalcogenides, and identify two contributions to this nonlinear optical process with opposite circularly polarized valley selection rules. In the non-interacting limit, the competition between the two contributions leads to a crossover of the selection rule with the increase of the two-photon energy. With the strong Coulomb interaction between the electron and hole, the two contributions excite electron-hole scattering states in orthogonal angular momentum channels, while the strength of the transition can be substantially enhanced by the interaction. Based on this picture of the two-photon transition, the second harmonic generation(SHG) in the electron-hole continuum is analyzed, where the Coulomb interaction is shown to greatly alter the relative strength of different cross-circular polarized SHG processes. Valley Current injection by the quantum interference of one-photon and two-photon transition is also investigated in the presence of the strong Coulomb interaction, which significantly enhances the injection rate.

关键词： 2D semiconductors Nonlinear optics Electron-hole continuum Two-photon transition Second-harmonic generation Valley Current injection

Experimental investigation of different brines imbibition influences on co-and counter-Current oil flows in carbonate reservoirs

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Chinese Journal of Chemical Engineering 2021年第5期34卷 17-29页

作者： Pouyan Ahmadi Mohammad Reza Aghajanzadeh Masoud Riazi Mohammad Reza Malayeri Mohammad Sharifi Enhanced Oil Recovery(EOR)Research Centre IOR/EOR Research InstituteShiraz UniversityShirazIran Helmholtz Centre for Environmental Research-UFZ LeipzigGermany Department of Petroleum Engineering Amirkabir University of TechnologyTehranIran Institut für Verfahrenstechnik und Umwelttechnik Technische Universität DresdenGermany

Imbibition of water,as wetting phase in oil-wet fractured carbonate reservoirs,plays a key role in fluid flow between matrix and fracture system.The type of injected seawater and its chemistry would profoundly influence the imbibition process.In this study,the impact of smart water(a brine that its ions have been adjusted to facilitate oil recovery)and low salinity water on co-and counter-Current imbibition processes for oil-wet carbonate cores has been experimentally investigated.The results show an increase of about 10% in oil recovery for co-and counter-Currents for smart seawater imbibition compared to that of low salinity seawater.In addition,as a result of the influence of co-and counter-Current on each other,by co-Current removal from one core face,the counterCurrent in the other face would be intensified by as much as about 75%.A close examination of different lengths(5,7 and 9 cm)of carbonate cores with the same permeability revealed that by decreasing porous medium length,the amount of counter-Current producing oil would be decreased so that in the 5 cm core,counter Current oil production will not happen.For similar core lengths by increasing permeability,the share of counter Current flow would be decreased approximately 18% since the capillary pressure could not overcome non-wetting phase viscous forces.Considering the role of matrix length along with a modified brine(which is designed according to the matrix mixture)strengthen the relevant mechanisms to have more oil production so that the higher thickness of matrix causes the higher amount of co-Current oil producing and consequently more total recovery.

关键词： Smart water Co-Current Counter Current Wettability alteration Oil recovery

Dermoscopy in China: Current status and future prospective

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Chinese Medical Journal 2019年第17期132卷 2096-2104页

作者： Xue Shen Rui-Xing Yu Chang-Bing Shen Cheng-Xu Li Yan Jing Ya-Jie Zheng Zi-Yi Wang Ke Xue Feng Xu Jian-Bin Yu Ru-Song Meng Yong Cui Department of Dermatology Chengdu Second People’s Hospital Chengdu Sichuan 610017 China Department of Dermatology China-Japan Friendship Hospital Beijing 100029 China Graduate School Peking Union Medical College and Chinese Academy of Medical Sciences Beijing 100730 China Department of Dermatology The First Affiliated Hospital of Anhui Medical University Hefei Anhui 230032 China Department of Dermatology Affiliated Chaohu Hospital of Anhui Medical University Hefei Anhui 238001 China Shanghai Wheat Color Intelligent Technology Company LTD Shanghai 200051 China Department of Dermatology The First Affiliated Hospital of Zhengzhou University Zhengzhou Henan 450052 China Department of Dermatology Specialty Medical Center of the Air Force Chinese People’s Liberation Army Beijing 100142 China

Objective: Dermoscopy is a useful technique for improving the diagnostic accuracy of various types of skin disorders. In China, dermoscopy has been widely accepted, and domestic researchers have made tremendous progress in the field of dermoscopy. The main purpose of this review is to summarize the Current status of dermoscopy in China and identify its future directions. Data sources: Articles included in this review were obtained by searching the following databases: Wanfang, China National Knowledge Infrastructure, PubMed, and the Web of Science. We focused on research published before 2019 with keywords including dermoscopy, dermoscopic, dermoscope and trichoscopy. Study selection: A total of 50 studies were selected. Of these studies, 20 studies were in Chinese and 30 in English, research samples of all the studies were collected from Chinese populations. Results: Since 2000, more than 380 articles about dermoscopy have been published in domestic or foreign journals. Dermoscopy can improve the diagnostic accuracy of neoplastic diseases, evaluating the therapeutic effect of treatment, and determining the treatment endpoint, and it can also assist in the differential diagnosis of inflammatory diseases and in the assessment of the severity of the disease. In addition, researches about the applications of dermoscopy during surgical treatment have been published. Training courses aiming to improve the diagnostic ability of dermatologists, either face-to-face or online, have been offered. The Chinese Skin Image Database, launched in 2017 as a work platform for dermatologists, has promoted the development of dermoscopy in China. Computer-aided diagnostic systems based on the Chinese population are ready for use. In the future, cooperation, resource sharing, talent development, image management, and computer-aided diagnosis will be important directions for the development of dermoscopy in China. Conclusion: Dermoscopy has been widely used and developed in China, however, it still needs to address more challenges in t

关键词： Dermoscopy China Current status Future

Optimization of ambipolar Current and analog/RF performance for T-shaped tunnel field-effect transistor with gate dielectric spacer

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Chinese Physics B 2019年第1期28卷 656-662页

作者：韩茹张海潮王党辉李翠 School of Computer Science and Engineering Northwestern Polytechnical University

A new T-shaped tunnel field-effect transistor(TTFET) with gate dielectric spacer(GDS) structure is proposed in this paper. To further studied the effects of GDS structure on the TTFET, detailed device characteristics such as Current-voltage relationships, energy band diagrams, band-to-band tunneling(BTBT) rate and the magnitude of the electric field are investigated by using TCAD simulation. It is found that compared with conventional TTFET and TTFET with gate-drain overlap(GDO) structure, GDS-TTFET not only has the minimum ambipolar Current but also can suppress the ambipolar Current under a more extensive bias range. Furthermore, the analog/RF performances of GDS-TTFET are also investigated in terms of transconductance, gate-source capacitance, gate-drain capacitance, cutoff frequency, and gain bandwidth production. By inserting a low-κ spacer layer between the gate electrode and the gate dielectric, the GDS structure can effectively reduce parasitic capacitances between the gate and the source/drain, which leads to better performance in term of cutoff frequency and gain bandwidth production. Finally, the thickness of the gate dielectric spacer is optimized for better ambipolar Current suppression and improved analog/RF performance.

关键词： tunneling field effect transistor T-shaped tunnel field-effect transistor gate dielectric spacer ambipolar Current analog/RF performance

A new approach for analyzing the effect of non-ideal power supply on a constant Current underwater cabled system

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Frontiers of Information Technology & Electronic Engineering 2020年第4期21卷 604-614页

作者： Yu-jia ZANG Yan-hu CHEN Can-jun YANG De-jun LI Ze-jian CHEN Gul MUHAMMAD The State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China

The effect of a constant Current(CC)power supply on the CC ocean observation system is a problem that once was neglected.The dynamic characteristics of the CC power supply may have great influence on the whole system,especially the voltage behavior in the event of load change.This needs to be examined.In this paper,a method is introduced to check whether the CC power supply can satisfy the dynamic requirements of the CC ocean observation system.An equivalent model to describe the non-ideal CC power supply is presented,through which the dynamic characteristics can be standardized.To verify the feasibility of this model,a minimum system of a single node in the CC ocean observation system is constructed,from which the model is derived.Focusing on the power failure problem,the output voltage responses are performed and the models are validated.Through the model,the dynamic behavior of the CC power supply is checked in a practical design.

关键词： Non-ideal power supply Constant Current input Ocean observation system

Tab engineering-mediated resistance of flexible lithium-ion batteries for high output Current

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Journal of Energy Chemistry 2021年第7期30卷 264-270页

作者： Shi Kui Jia Bin Ze Yang Chao Feng Zhao Zhi Yong Zhang Yan Hong Yin Xian Bin Liu Ying Yan Hu Zi Ping Wu School of Materials Science and Engineering Jiangxi University of Science and TechnologyGanzhou 341000JiangxiChina

Flexible lithium-ion batteries(LIBs) have received tremendous interest because they can provide essential flexible power for the emerging wearable electronics.However,the realization of the flexibility of LIBs is often related to flexible substrates with high electrical resistance,which results in voltage loss of the battery and is unfavorable for their practical applications.In this work,we demonstrated the use of tab engineering to mediate the resistance of flexible batteries for high Current output.The resistance of the obtained pouch cell can be decreased sharply and the output Current can be significantly increased by a continuous tab with desirable power and energy density.The surprising performance of the flexible LIBs allows the tab on the Current collector providing enough channels for electron transfer,thus enabling electrons to be transferred quickly and enhancing the electrochemical reaction kinetics.Such a flexible battery with sufficient output Current could possibly solve some of the most critical problems for their practical applications in wearable electronics.

关键词： Flexible batteries Tabs Current Carbon nanotube Wearable electronics

An innovative method for the microstructural modification of TiAl alloy solidified via direct electric Current application

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Journal of Materials Science & Technology 2019年第1期35卷 23-28页

作者： Zhanxing Chen Hongsheng Ding Ruirun Chen Shiqiu Liu Jingjie Guo Hengzhi Fu National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and Engineering Harbin Institute of Technology

Ti-48Al-2Cr-2Nb alloy solidified with the application of direct electric Current has a refined and homogeneous microstructure without segregation. We observed an initial decrease followed by a subsequent increase in grain size and lamellar spacing, with the increase in Current density. Similar trend can also be obtained by varying the amount of α2-phase(Ti_3Al). Using a directional solidification processing method,the columnar crystal microstructure transforms into an equiaxed crystal microstructure at a Current density of 32–64 m A/mm^2. High dislocation density is also introduced with a minimum cross-sectional grain size of 460 μm at a Current density of 64 mA/mm^2. The application of electric Current alters the free energy of the critical nucleus and temperature via joule heating, causing a transformation from a columnar grain microstructure into an equiaxed grain microstructure. The increase in Current density leads to a rise of the nucleation rate, and a resulting undercooling combined with temperature gradient contribute to growth of the primary phase, which finally results in grain coarsening at a critical Current density of 96 mA/mm^2.The climb and cross-slip of dislocation and the migration of grain boundary ultimately create variable lamellae spacing of TiAl alloy.

关键词： TiAl Solidification Direct electric Current Microstructure

Study on influencing factors of ion Current density measurement in corona discharge of HVDC transmission lines

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Plasma Science and Technology 2020年第4期22卷 1-7页

作者：刘士强李守正姜雨泽姜楠李杰吴彦 School of Electrical Engineering Dalian University of TechnologyDalian 116024People's Republic of China State Grid Shandong Electric Power Research Institute Jinan 250003People's Republic of China

The ground level ion Current density produced by corona discharge in high voltage direct Current(HVDC)transmission lines can reflect the operation status of the lines,but the distorted electric field at the edge of the Wilson plate seriously affects the measurement results of ion Current density.In order to measure the ground level ion Current density accurately and directly,a new reduced scale wire-plate experimental device in which the Wilson plate is flush with the grounding plate is designed.The influence of protective annulus width and the height of the Wilson plate from the grounding plate on ground level ion Current density are studied.In addition,the differences between the micro-Current galvanometer method and the sampling resistance method in the measurement of ion Current density are compared.Finally,the ground level ion Current density distributions of unipolar and bipolar HVDC transmission lines are measured.The results show that the edge effect of the Wilson plate can be neglected when the width of protective annulus is less than 2 mm,and the ion Current density is nonlinear with the height of the Wilson plate from the grounding plate.Moreover,the internal resistance of the digital voltmeter seriously affects the measurement results and it is necessary to correct the results.Finally,at the same applied voltage,the ground level ion Current density in the negative conductor region is higher than that in the positive conductor region.

关键词： HVDC corona discharge reduced scale device Wilson plate ion Current density