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Light(Science & Applications) 2024年第6期13卷 1159-1169页

作者： Yufan Kang yongfeng pei Dong He Hang Xu Mingjun Ma Jialu Yan Changzhong Jiang Wenqing Li Xiangheng Xiao School of Physics and Technology Key Lab of Artificial Micro-and Nano-Structures of Ministry of EducationWuhan UniversityWuhanChina

The construction of lateral p-n junctions is very important and challenging in two-dimensional(2D)semiconductor manufacturing *** researches have demonstrated that vertical p-n junction can be prepared simply by vertical stacking of 2D ***,interface pollution and large area scalability are challenges that are difficult to overcome with vertical stacking *** 2D lateral p-n homojunction is an effective strategy to address these *** selective p-type doping of 2D semiconductors is expected to construct lateral p-n *** this work,we have developed a low-energy ion implantation system that reduces the implanted energy to 300 ***-energy implantation can form a shallow implantation depth,which is more suitable for modulating the electrical and optical properties of 2D ***,we utilize low-energy ion implantation to directly dope nitrogen ions into few-layer WS_(2) and successfully realize a precise regulation for WS_(2) with its conductivity type transforming from n-type to bipolar or even p-type ***,the universality of this method is demonstrated by extending it to other 2D semiconductors,including WSe_(2),SnS_(2) and MoS_(2).Based on this method,a lateral WS_(2) p-n homojunction is fabricated,which exhibits significant rectification characteristics.A photodetector based on p-n junction with photovoltaic effect is also prepared,and the open circuit voltage can reach to 0.39 *** work provides an effective way for controllable doping of 2D semiconductors.

关键词： implantation doping Spatial

Lewis acid-doped transition metal dichalcogenides for ultraviolet–visible photodetectors

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Chinese Physics B 2024年第9期33卷 628-635页

作者： Heng Yang Mingjun Ma yongfeng pei Yufan Kang Jialu Yan Dong He Changzhong Jiang Wenqing Li Xiangheng Xiao School of Physics and Technology Key Laboratory of Artificial Micro-and Nano-Structures of Ministry of EducationWuhan UniversityWuhan 430072China Wuhan Research Center for Infectious Diseases and Cancer Chinese Academy of Medical SciencesWuhan 430072China

Ultraviolet photodetectors(UV PDs)are widely used in civilian,scientific,and military fields due to their high sensitivity and low false alarm *** present a temperature-dependent Lewis acid p-type doping method for transition metal dichalcogenides(TMDs),which can effectively be used to extend the optical response *** p-type doping based on surface charge transfer involves the chemical adsorption of the Lewis acid SnCl_(4)as a light absorption layer on the surface of WS_(2),significantly enhancing its UV photodetection *** 365 nm laser irradiation,WS_(2)PDs exhibit response speed of 24 ms/20 ms,responsivity of 660 mA/W,detectivity of 3.3×10^(11)Jones,and external quantum efficiency of 226%.Moreover,we successfully apply this doping method to other TMDs materials(such as MoS_(2),MoSe_(2),and WSe_(2))and fabricate WS_(2) lateral p–n heterojunction PDs.

关键词： two-dimensional (2D) materials p-type doping transition metal dichalcogenides photodetectors

Recent progress about 2D metal dichalcogenides: Synthesis and application in photodetectors

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Nano Research 2021年第6期14卷 1819-1839页

作者： yongfeng pei Rui Chen Hang Xu Dong He Changzhong Jiang Wenqing Li Xiangheng Xiao Department of Physics and Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education Hubei Nuclear Solid Physics Key LaboratoryWuhan UniversityWuhan430072China

In recent years, two-dimensional (2D) layered metal dichalcogenides (MDCs) have received enormous attention on account of their excellent optoelectronic properties. Especially, various MDCs can be constructed into vertical/lateral heterostructures with many novel optical and electrical properties, exhibiting great potential for the application in photodetectors. Therefore, the batch production of 2D MDCs and their heterostructures is crucial for the practical application. Recently, the vapour phase methods have been proved to be dependable for growing large-scale MDCs and related heterostructures with high quality. In this paper, we summarize the latest progress about the synthesis of 2D MDCs and their heterostructures by vapour phase methods. Particular focus is paid to the control of influence factors during the vapour phase growth process. Furthermore, the application of MDCs and their heterostructures in photodetectors with outstanding performance is also outlined. Finally, the challenges and prospects for the future application are presented.

关键词： metal dichalcogenides vertical/lateral heterostructures vapour phase methods photodetectors

Intrinsic defects of nonprecious metal electrocatalysts for energy conversion: Synthesis, advanced characterization, and fundamentals

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ChemPhysMater 2022年第3期1卷 155-182页

作者： Menghua Yang Jiangchao Liu Hang Xu yongfeng pei Changzhong Jiang Dong He Xiangheng Xiao Department of Physics Hubei Nuclear Solid Physics Key LaboratoryWuhan UniversityWuhan 430072China Hubei Yangtze Memory Laboratories Wuhan 430205China

With the depletion of fossil fuels and environmental pollution, energy storage and conversion have become the focus of current research. Water splitting and fuel cell technologies have made outstanding contributions to energy conversion. However, the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) have slow kinetics, which limit the capacity of fuel cells. It is of great significance to develop catalysts for the OER and ORR and continuously improve their catalytic performance. Many studies have shown that intrinsic defects, especially vacancies (anion and cation vacancies), can effectively improve the efficiency of electrochemical energy storage and conversion. The introduction of intrinsic defects can generally expose more active sites, enhance conductivity, adjust the electronic state, and promote ion diffusion, thereby enhancing the catalytic performance. This review comprehensively summarizes the latest developments regarding the effects of intrinsic defects on the performance of non-noble metal electrocatalysts. According to the type of intrinsic defect, this article reviews in detail the regulation mechanism, preparation methods and advanced characterization techniques of intrinsic defects in different materials (oxides, non-oxides, etc.). Then, the current difficulties and future development of intrinsic defect regulation are analyzed and discussed thoroughly. Finally, the prospect of intrinsic defects in the field of electrochemical energy storage is further explored.

关键词： Intrinsic defects Anion vacancies Cation vacancies Transition metal-based materials Electrochemical energy conversion

Analysis on ignition and extinction of n-heptane in homogeneous systems

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Science China(Technological Sciences) 2005年第5期48卷 556-569页

作者： LIU yongfeng1 & pei Pucheng2 1. Mechanical and Electrical Engineering Department, Beijing Institute of Civil Engineering and Architec-ture, Beijing 100044, China 2. State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084, China Mechanical and Electrical Engineering Department Beijing Institute of Civil Engineering and Architecture Beijing 100044 China

To calculate ignition delay times, the governing equations about species and temperature, which are in a closed volume based on the theory of thermal explosion and in a continuously stirred flow reactor, are deducted. The method referred to steady state assumptions is based on the observation that due to very fast chemical processes in combustion problems many chemical species and reactions are in a quasi-steady state or partial equilibrium. When a species is assumed to be in the steady state, the corresponding differential equation can be replaced by an algebraic relation, which reduces the computational costs. The steady state solution of the reactor equations describes the three ignition temperature regimes and get “S-shaped curve”. The reduced simplified 4-step mechanism for n-heptane from 1011 elementary reactions leads with the steady state assumptions to linear differential equations, which is solved. The simulation results of the 4-step reduced mechanism for n-heptane are fitted well with the experiment data. At last, two important parameters are discussed thoroughly and the temperature perturbation is given. It reduces the computational efforts considerably without losing too much accuracy and further supplies numerical methods for turbulent combustion in the diesel engine.

关键词： ignition delay times, thermal runaway, steady state assumptions, continuously stirred flow reactor.

Design of efficient thermoelectric generators

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Science China Materials 2024年第1期67卷 377-378页

作者： Min Liu Yanzhong pei Interdisciplinary Materials Research Center School of Materials Science and EngineeringTongji UniversityShanghai 201804China

Thermoelectricity,which enables direct conversion between heat and electricity,undergoes impressive developments in recent decades,and is particularly promising for recovering low-grade heat of<600 K[1,2].Currently,only Bi2Te3-based thermoelectric devices are commercialized[3].However,the scarcity of tellurium(Te)(Fig.1a)is the main *** leads to numerous recent efforts on the development of efficient nonBi2Te3 thermoelectrics as potential alternatives,and successful examples(Fig.1b)include Mg3Sb2-alloys[2,3]and MgAgSb[1,2].

关键词： enable efficient electricity

Relationship between seismic structures and the diverse rupture processes of the 2023 Türkiye earthquake doublet

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Science China Earth Sciences 2024年第9期67卷 2810-2823页

作者： Zhi WANG Yi FU Shunping pei CAS Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Recent geodetic and seismological observations of two major earthquakes in southeastern Türkiye in February 2023 have revealed complex rupture initiation,propagation,and segmentation along the East Anatolian Fault Zone(EAFZ)and surrounding ***,the role of upper crust structures along the EAFZ in determining the diverse rupture processes of this earthquake doublet remains *** further investigate this,we employed double-difference location and seismic tomography techniques to determine high-resolution seismic velocities(V_(P),V_(S))and Poisson’s ratio(σ)structures using a multiparameter joint tomographic *** dataset includes 100,833 high-quality source-receiver travel-time pairs of P-and *** find that the unique rupture processes of this earthquake doublet were primarily influenced by contrasting crustal seismic structures and localized geological *** M_(w)7.8 mainshock was initiated within a transitional edge zone characterized by a rigid part(asperity)of the seismogenic zone with sharp contrast variations in rock strength ranging from low to high along the *** comparison,the M_(w)7.6 rupture originated in a ductile belt featuring fluid saturation with low-VP,low-VS,and high-σvalues that extended parallel to the Cardak *** pronounced contrast structures observed along the former rupture can be attributed to the oblique collision system between the weakened section of the east Anatolian plateau and the brittle Arabian platform,while the latter rupture was initiated within the ductile structure associated with fluid intrusion caused by the northward subduction of the Cyprus slab and subsequent ***,the occurrence of the first earthquake(E1)serves to alleviate shear stress on the second earthquake(E2)fault,potentially impeding the initiation of an E2 *** the contrary,this event also significantly reduces the normal stress acting on the E2 fault due to a double left-lateral strike-slip system

关键词： 2023 Turkiye earthquake doublet Joint seismic tomography Tomographic transition edge Seismic rupture process Strong fault coupling

Study on 6-DOF active vibration-isolation system of the ultra-precision turning lathe based on GA-BP-PID control for dynamic loads

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Advances in Manufacturing 2024年第1期12卷 33-60页

作者： Bo Wang Zhong Jiang pei-Da Hu Department of Precision Instrument Tsinghua UniversityBeijing100084People’s Republic of China Institute of Machinery Manufacturing Technology China Academy of Engineering PhysicsMianyang621900SichuanPeople’s Republic of China

The vibration disturbance from an external environment affects the machining accuracy of ultra-precision machining *** active vibration-isolation systems(AVIS)have been developed based on static *** a vibration-isolation load changes dynamically during ultra-precision turning lathe machining,the system parameters change,and the efficiency of the active vibration-isolation system based on the traditional control strategy *** solve this problem,this paper proposes a vibration-isolation control strategy based on a genetic algorithm-back propagation neural network-PID control(GA-BP-PID),which can automatically adjust the control parameters according to the machining ***-isolation simulations and experiments based on passive vibration isolation,a PID algorithm,and the GA-BP-PID algorithm under dynamic load machining conditions were *** experimental results demonstrated that the active vibration-isolation control strategy designed in this study could effectively attenuate vibration disturbances in the external environment under dynamic load *** design is reasonable and feasible.

关键词： Ultra-precision diamond turning lathe Active vibration isolation Six degrees of freedom Dynamic load Genetic algorithm-back propagation neural network-PID(GA-BP-PID)control

Performance analysis of a photovoltaic/thermal system with lunar regolith-based thermal storage for the lunar base

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Science China(Technological Sciences) 2024年第4期67卷 1113-1123页

作者： SUN WenGan ZHAO Bin pei Yu SHI LingFeng HU MaoBin LI MuJun REN Xiao pei Gang Deep Space Exploration Laboratory Hefei 230026China Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei 230026China Department of Mechanical and Aerospace Engineering University of California San DiegoLa JollaCA 92093USA Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei 230026China College of New Energy China University of Petroleum(East China)Qingdao 266000China

Powering a moon base,especially keeping it warm during the long lunar night,is a big *** paper introduces a photovoltaic/thermal(PV/T)system incorporating regolith thermal storage to solve the challenge of power and heat provision for the lunar base *** vacuum of space around the moon helps this system by reducing heat *** the moon's daytime,the system not only generates electricity but also captures *** stored heat in the regolith is then used at night,reducing the amount of equipment we need to send from *** spectrally selective PV/T panels are designed to absorb a wide range of sunlight(0.3–2.5μm)while minimizing heat loss in the infrared range(3–30μm).Simulation results of the hybrid solar energy system indicate the average value of the overall efficiency is 45.9%,which relatively elevates 56.1%compared to the PV *** launch mass of the proposed PV/T system is only 8.4%of a traditional photovoltaic-lithium battery system with the same amount of energy *** the total specific energy of the proposed system is 7.3 kWh kg^(-1),while that of the photovoltaic-lithium battery system is about 0.3 kWh kg^(-1).In summary,this study proposes an alternative combined heat and electricity supply system for the lunar base,which can greatly reduce the launch mass and free up load for other scientific research equipment.

关键词： in-situ resource utilization(IRSU) regolith thermal storage photovoltaic/thermal(PV/T) spectral selectivity

Numerical study of submerged bending vegetation under unidirectional flow

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Water Science and Engineering 2024年第1期17卷 92-100页

作者： pei-pei Zhang Yi-qing Gong Ken Vui Chua Jie Dai Jing-qiao Mao College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China Institute of Water Science and Technology Hohai UniversityNanjing 210098China School of Engineering Cardiff UniversityCardiff CF243AAUK

Submerged vegetation commonly grows and plays a vital role in aquatic ecosystems,but it is also regarded as a barrier to the passing *** simulations of flow through and over submerged vegetation were carried out to investigate the effect of vegetation density on flow *** simulations were computationally set up to replicate flume experiments,in which vegetation was mimicked with flexible plastic *** fluid-structure interaction between flow and flexible vegetation was solved by coupling the two modules of the COMSOL *** cases with different vegetation densities were simulated,and the results were successfully validated against the experimental *** contours of the simulated time-averaged streamwise velocity and Reynolds stress were extracted to highlight the differences in mean and turbulent flow *** turbulence intensity was found to be more sensitive to vegetation density than the time-averaged *** developing length increased with the spacing between *** snapshots of the bending vegetation under instantaneous velocity and vorticity revealed that flexible vegetation responded to the effects of eddies in the shear layer by swaying *** first two rows of vegetation suffered stronger approaching flow and were prone to more streamlined *** addition,the origin of tip vortices was investigated via the distribution of *** results reveal the variation of flow properties with bending submerged vegetation and provide useful reference for optimizationofrestorationprojects.

关键词： Computational fluid dynamics Fluid-structure interaction Turbulence Flexible and submerged vegetation