Graphene, with its zero-bandgap electronic structure, is a highly promising ultra-broadband light absorbing material.However, the performance of graphene-based photodetectors is limited by weak absorption efficiency a...Graphene, with its zero-bandgap electronic structure, is a highly promising ultra-broadband light absorbing material.However, the performance of graphene-based photodetectors is limited by weak absorption efficiency and rapid recombination of photoexcited carriers, leading to poor photodetection performance. Here, inspired by the photogating effect, we demonstrated a highly sensitive photodetector based on graphene/WSe_(2) vertical heterostructure where the WSe_(2) layer acts as both the light absorption layer and the localized grating layer. The graphene conductive channel is induced to produce more carriers by capacitive coupling. Due to the strong light absorption and high external quantum efficiency of multilayer WSe_(2), as well as the high carrier mobility of graphene, a high photocurrent is generated in the vertical heterostructure. As a result, the photodetector exhibits ultra-high responsivity of 3.85×10~4A/W and external quantum efficiency of 1.3 × 10~7%.This finding demonstrates that photogating structures can effectively enhance the sensitivity of graphene-based photodetectors and may have great potential applications in future optoelectronic devices.展开更多
Recently,it has been proposed that spin torque oscillators(STOs)and spin torque diodes could be used as artificial neurons and synapses to directly process microwave signals,which could lower latency and power consump...Recently,it has been proposed that spin torque oscillators(STOs)and spin torque diodes could be used as artificial neurons and synapses to directly process microwave signals,which could lower latency and power consumption greatly.However,one critical challenge is to make the microwave emission frequency of the STO stay constant with a varying input current.In this work,we study the microwave emission characteristics of STOs based on magnetic tunnel junction with MgO cap layer.By applying a small magnetic field,we realize the invariability of the microwave emission frequency of the STO,making it qualified to act as artificial neuron.Furthermore,we have simulated an artificial neural network using STO neuron to recognize the handwritten digits in the Mixed National Institute of Standards and Technology database,and obtained a high accuracy of 92.28%.Our work paves the way for the development of radio-frequency-oriented neuromorphic computing systems.展开更多
High-entropy materials,composed of five or more elements in near-equiatomic percentage,have been attracting tremendous interests due to their advantageous properties in a variety of applications.Recently,electrocataly...High-entropy materials,composed of five or more elements in near-equiatomic percentage,have been attracting tremendous interests due to their advantageous properties in a variety of applications.Recently,electrocatalysis on high-entropy alloys(HEAs)and high-entropy compounds(HECs)has emerged as a new and promising material owing to the tailored composition and the disordered con-figuration of HEAs and HECs.Though extensive efforts have been devoted to investigating the catalytic nature of HEAs and HECs,the details related to the active sites and intrinsic activity of such catalysts still remain uncertain due to the complexity of the multicomponent systems.In this review,the recent progress of HEAs and HECs is systematically reviewed in terms of their synthetic strate-gies and electrocatalytic applications.Importantly,the computationally assisted methods(e.g.,density functional theory[DFT])are also presented to discover and design the optimumHEA-andHEC-based catalysts.Subsequently,the appli-cations of HEAs and HECs in electrocatalytic energy conversion reactions will be discussed,including hydrogen evolution reaction,oxygen evolution reaction,oxygen reduction reaction,carbon dioxide reduction reaction,nitrogen reduction reaction,methanol oxidation reaction,and ethanol oxidation reaction(EOR).Moreover,the prospects and future opportunities for this research field are cau-tiously discussed.A series of upcoming challenges and questions are thoroughly proposed from the experimental and theoretical aspects as well as other future applications in electrocatalysis.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.11974379)the National Key Basic Research and Development Program of China (Grant No.2021YFC2203400)Jiangsu Vocational Education Integrated Circuit Technology “Double-Qualified” Famous Teacher Studio (Grant No.2022-13)。
文摘Graphene, with its zero-bandgap electronic structure, is a highly promising ultra-broadband light absorbing material.However, the performance of graphene-based photodetectors is limited by weak absorption efficiency and rapid recombination of photoexcited carriers, leading to poor photodetection performance. Here, inspired by the photogating effect, we demonstrated a highly sensitive photodetector based on graphene/WSe_(2) vertical heterostructure where the WSe_(2) layer acts as both the light absorption layer and the localized grating layer. The graphene conductive channel is induced to produce more carriers by capacitive coupling. Due to the strong light absorption and high external quantum efficiency of multilayer WSe_(2), as well as the high carrier mobility of graphene, a high photocurrent is generated in the vertical heterostructure. As a result, the photodetector exhibits ultra-high responsivity of 3.85×10~4A/W and external quantum efficiency of 1.3 × 10~7%.This finding demonstrates that photogating structures can effectively enhance the sensitivity of graphene-based photodetectors and may have great potential applications in future optoelectronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974379 and 12204357)K.C.Wong Education Foundation(Grant No.GJTD2019-14)+2 种基金Jiangxi Province“Double Thousand Plan”(Grant No.S2019CQKJ2638)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.22KB140017)Wuxi University Research Start-up Fund for Introduced Talents(Grant No.2022r006)。
文摘Recently,it has been proposed that spin torque oscillators(STOs)and spin torque diodes could be used as artificial neurons and synapses to directly process microwave signals,which could lower latency and power consumption greatly.However,one critical challenge is to make the microwave emission frequency of the STO stay constant with a varying input current.In this work,we study the microwave emission characteristics of STOs based on magnetic tunnel junction with MgO cap layer.By applying a small magnetic field,we realize the invariability of the microwave emission frequency of the STO,making it qualified to act as artificial neuron.Furthermore,we have simulated an artificial neural network using STO neuron to recognize the handwritten digits in the Mixed National Institute of Standards and Technology database,and obtained a high accuracy of 92.28%.Our work paves the way for the development of radio-frequency-oriented neuromorphic computing systems.
基金the National Natural Science Foundation of China,Grant/Award Number:51802252Singapore Ministry of Education(MOE)Academic Research Fund,Grant/Award Number:2020-T1-001-031+4 种基金National Research Foundation of Singapore,Grant/Award Number:NRF2016NRF-NRFI001-22Natural Science Foundation of Shaanxi Province,Grant/Award Num-bers:2021JQ-015,2020JM-032Natural Science Foundation of Jiangsu Province,Grant/Award Number:BK20200242Higher Education Discipline Innovation Project of China,Grant/Award Numbers:BP200618008,D18023Postdoctoral Science Foundation of China,Grant/Award Number:2021M692546。
文摘High-entropy materials,composed of five or more elements in near-equiatomic percentage,have been attracting tremendous interests due to their advantageous properties in a variety of applications.Recently,electrocatalysis on high-entropy alloys(HEAs)and high-entropy compounds(HECs)has emerged as a new and promising material owing to the tailored composition and the disordered con-figuration of HEAs and HECs.Though extensive efforts have been devoted to investigating the catalytic nature of HEAs and HECs,the details related to the active sites and intrinsic activity of such catalysts still remain uncertain due to the complexity of the multicomponent systems.In this review,the recent progress of HEAs and HECs is systematically reviewed in terms of their synthetic strate-gies and electrocatalytic applications.Importantly,the computationally assisted methods(e.g.,density functional theory[DFT])are also presented to discover and design the optimumHEA-andHEC-based catalysts.Subsequently,the appli-cations of HEAs and HECs in electrocatalytic energy conversion reactions will be discussed,including hydrogen evolution reaction,oxygen evolution reaction,oxygen reduction reaction,carbon dioxide reduction reaction,nitrogen reduction reaction,methanol oxidation reaction,and ethanol oxidation reaction(EOR).Moreover,the prospects and future opportunities for this research field are cau-tiously discussed.A series of upcoming challenges and questions are thoroughly proposed from the experimental and theoretical aspects as well as other future applications in electrocatalysis.
