A heterostructure photodetector composed of few-layer NiPS_(3)/WS_(2)is made by using mechanical exfoliation and micro-nano fabrication techniques.The photodetector exhibits a broad-band response wavelengths of rangin...A heterostructure photodetector composed of few-layer NiPS_(3)/WS_(2)is made by using mechanical exfoliation and micro-nano fabrication techniques.The photodetector exhibits a broad-band response wavelengths of ranging of 405 nm and 800 nm.Under the light illumination of 405-nm wavelength and a bias voltage of-2V,the photoresponsivity is 62.6 m A/W and the specific detectivity is 8.59×10^(10)Jones.In addition,the device demonstrates a relatively fast response with rise and fall times of 70 ms and 120 ms.Theoretical calculation suggest that this excellent performance can be ascribed to the type-Ⅱband alignment at the NiPS_3/WS_2 heterostructure interface.展开更多
WS_(2),a two-dimensional layered material,is promising as sodium-ion batteries(SIBs)anode due to its large lnterlamellar spacing and high sodium storage capacity.However,its low electronic conductivity and high Na^(+)...WS_(2),a two-dimensional layered material,is promising as sodium-ion batteries(SIBs)anode due to its large lnterlamellar spacing and high sodium storage capacity.However,its low electronic conductivity and high Na^(+)adsorption energy hinder reaction kinetics.Here we demonstrate that substituting Se for part of the S in WS_(2)reduces interlayer Na^(+)adsorption and increases electronic conductivity.Based on this finding,lamellar WSSe,grown in situ on peanut shell-derived carbon(PSDC/WSSe),is elaborately designed as a highly stable SIB anode with a fast kinetic.PSDC/WSSe with carbon matrix and Se substitution simultaneously provides fast electron transport channels and lowered Na^(+)transport barriers(0.22 eV).The PSDC/WSSe anode offers a considerable reversible sodium storage capacity(288.0 mAh g^(-1)after 1000 cycles at 1.0 A g^(-1))and a fast kinetic reaction.A SIB full-cell using a PSDC/WSSe anode and Na_(3)V_(2)(PO_(4))_(3)cathode achieves a 215.4 Wh kg^(-1)high energy density,and successfully powers LEDs.This work offers new strategies to lower sodium ion transportation barrier in two-dimensional layered materials.展开更多
Despite significant progress has been achieved regarding the shuttle-effect of lithium polysulfides,the suppressed specific capacity and retarded redox kinetics under high sulfur loading still threat the actual energy...Despite significant progress has been achieved regarding the shuttle-effect of lithium polysulfides,the suppressed specific capacity and retarded redox kinetics under high sulfur loading still threat the actual energy density and power density of lithium-sulfur batteries.In this study,a graham condenser-inspired carbon@WS_(2)host with coil-in-tube structure was designed and synthesized using anodic aluminum oxide(AAO)membrane with vertically aligned nanopores as template.The vertical array of carbon nanotubes with internal carbon coils not only leads to efficient charge transfer across through the thickness of the cathode,but also provides significant confinement to polysulfide diffusion towards both the lateral and longitudinal directions.Few-layer WS_(2)in the carbon coils perform a synergistic role in suppressing the shuttle-effect as well as boosting the cathodic kinetics.As a result,high specific capacity(1180 m Ah/g at 0.1 C)and long-cycling stability at 0.5 C for 500 cycles has been achieved at 3 mgS/cm^(2).Impressive areal capacity of 7.4 m Ah/cm^(2)has been demonstrated when the sulfur loading reaches 8.4 mg/cm^(2).The unique coil-in-tube structure developed in this work provides a new solution for high sulfur loading cathode towards practical lithium-sulfur batteries.展开更多
Insight into exciton dynamics of two-dimensional(2D)transition metal dichalcogenides(TMDs)is critical for the optimization of their performance in photonic and optoelectronic devices.Although current researches have p...Insight into exciton dynamics of two-dimensional(2D)transition metal dichalcogenides(TMDs)is critical for the optimization of their performance in photonic and optoelectronic devices.Although current researches have primarily concentrated on the near-resonant excitation scenario in 2D TMDs,the case of excitation energies resonating with highenergy excitons or higher energies has yet to be fully elucidated.Here,a comparative analysis is conducted between highenergy excitation(360 nm)and near-resonant excitation(515 nm)utilizing transient absorption spectroscopy to achieve a comprehensive understanding of the exciton dynamics within monolayer WS_(2).It is observed that the high-energy C-exciton can be generated via an up-conversion process under 515 nm excitation,even the energy of which is less than that of the C-exciton.Furthermore,the capacity to efficiently occupy band-edge A-exciton states leads to longer lifetimes for both the C-excitons and the A-excitons under conditions of near-resonant excitation,accompanied by an augmented rate of radiative recombination.This study provides a paradigm for optimizing the performance of 2D TMDs-based devices by offering valuable insights into their exciton dynamics.展开更多
Silicon nitride photonics has emerged as a promising integrated optical platform due to its broad transparency window,low optical loss,and mature fabrication technology.However,the inherent centrosymmetric crystal str...Silicon nitride photonics has emerged as a promising integrated optical platform due to its broad transparency window,low optical loss,and mature fabrication technology.However,the inherent centrosymmetric crystal structure of silicon nitride fundamentally restricts its applications in second-order nonlinear optical processes.Monolayer transition metal dichalcogenides,particularly tungsten disulfide(WS_(2)),exhibit strong second-order nonlinear responses,making them ideal candidates for nonlinear photonic applications.Herein,we demonstrate a heterogeneously integrated platform combining silicon nitride waveguides with chemical vapor deposition(CVD)-grown monolayer WS_(2),enabling second harmonic generation.A specially designed silica cladding featuring gentle-slope profile on silicon nitride strip waveguides facilitates the integration of centimeter-scale WS_(2)film with photonic circuits.This approach provides a robust solution for incorporating second-order nonlinearity into silicon nitride photonic systems.The demonstrated platform holds significant potential for advancing quantum networks,visible-light lasers,and integrated optical modulation/detection systems.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFE0109200)the National Natural Science Foundation of China(Grant Nos.12074013 and 62175210)。
文摘A heterostructure photodetector composed of few-layer NiPS_(3)/WS_(2)is made by using mechanical exfoliation and micro-nano fabrication techniques.The photodetector exhibits a broad-band response wavelengths of ranging of 405 nm and 800 nm.Under the light illumination of 405-nm wavelength and a bias voltage of-2V,the photoresponsivity is 62.6 m A/W and the specific detectivity is 8.59×10^(10)Jones.In addition,the device demonstrates a relatively fast response with rise and fall times of 70 ms and 120 ms.Theoretical calculation suggest that this excellent performance can be ascribed to the type-Ⅱband alignment at the NiPS_3/WS_2 heterostructure interface.
基金financially supported by the Key R&D Plan of Shaanxi Province(Grant No.2023-YBGY-492)financial support from the Australian Research Councilthe QUT Capacity Building Professor Program。
文摘WS_(2),a two-dimensional layered material,is promising as sodium-ion batteries(SIBs)anode due to its large lnterlamellar spacing and high sodium storage capacity.However,its low electronic conductivity and high Na^(+)adsorption energy hinder reaction kinetics.Here we demonstrate that substituting Se for part of the S in WS_(2)reduces interlayer Na^(+)adsorption and increases electronic conductivity.Based on this finding,lamellar WSSe,grown in situ on peanut shell-derived carbon(PSDC/WSSe),is elaborately designed as a highly stable SIB anode with a fast kinetic.PSDC/WSSe with carbon matrix and Se substitution simultaneously provides fast electron transport channels and lowered Na^(+)transport barriers(0.22 eV).The PSDC/WSSe anode offers a considerable reversible sodium storage capacity(288.0 mAh g^(-1)after 1000 cycles at 1.0 A g^(-1))and a fast kinetic reaction.A SIB full-cell using a PSDC/WSSe anode and Na_(3)V_(2)(PO_(4))_(3)cathode achieves a 215.4 Wh kg^(-1)high energy density,and successfully powers LEDs.This work offers new strategies to lower sodium ion transportation barrier in two-dimensional layered materials.
基金the National Natural Science Foundation of China(Nos.22075027,52003030)Starting Grant from Beijing Institute of Technology and financial support from the State Key Laboratory of Explosion Science and Safety Protection(Nos.YBKT2106,YBKT23-05)Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘Despite significant progress has been achieved regarding the shuttle-effect of lithium polysulfides,the suppressed specific capacity and retarded redox kinetics under high sulfur loading still threat the actual energy density and power density of lithium-sulfur batteries.In this study,a graham condenser-inspired carbon@WS_(2)host with coil-in-tube structure was designed and synthesized using anodic aluminum oxide(AAO)membrane with vertically aligned nanopores as template.The vertical array of carbon nanotubes with internal carbon coils not only leads to efficient charge transfer across through the thickness of the cathode,but also provides significant confinement to polysulfide diffusion towards both the lateral and longitudinal directions.Few-layer WS_(2)in the carbon coils perform a synergistic role in suppressing the shuttle-effect as well as boosting the cathodic kinetics.As a result,high specific capacity(1180 m Ah/g at 0.1 C)and long-cycling stability at 0.5 C for 500 cycles has been achieved at 3 mgS/cm^(2).Impressive areal capacity of 7.4 m Ah/cm^(2)has been demonstrated when the sulfur loading reaches 8.4 mg/cm^(2).The unique coil-in-tube structure developed in this work provides a new solution for high sulfur loading cathode towards practical lithium-sulfur batteries.
基金supported by the National Natural Science Foundation of China(Grant Nos.12474421 and 12104066)the Fund from Education Department of Jilin Province(Grant Nos.JJKH20250473KJ and JJKH20241413KJ)the Fund from Department of Science and Technology of Jilin Province(Grant No.YDZJ202101ZYTS041)。
文摘Insight into exciton dynamics of two-dimensional(2D)transition metal dichalcogenides(TMDs)is critical for the optimization of their performance in photonic and optoelectronic devices.Although current researches have primarily concentrated on the near-resonant excitation scenario in 2D TMDs,the case of excitation energies resonating with highenergy excitons or higher energies has yet to be fully elucidated.Here,a comparative analysis is conducted between highenergy excitation(360 nm)and near-resonant excitation(515 nm)utilizing transient absorption spectroscopy to achieve a comprehensive understanding of the exciton dynamics within monolayer WS_(2).It is observed that the high-energy C-exciton can be generated via an up-conversion process under 515 nm excitation,even the energy of which is less than that of the C-exciton.Furthermore,the capacity to efficiently occupy band-edge A-exciton states leads to longer lifetimes for both the C-excitons and the A-excitons under conditions of near-resonant excitation,accompanied by an augmented rate of radiative recombination.This study provides a paradigm for optimizing the performance of 2D TMDs-based devices by offering valuable insights into their exciton dynamics.
基金Project supported by the National Innovative Training Program for College Students of China(Grant No.2023069)the University Research and Innovation Project of the National University of Defense Technology。
文摘Silicon nitride photonics has emerged as a promising integrated optical platform due to its broad transparency window,low optical loss,and mature fabrication technology.However,the inherent centrosymmetric crystal structure of silicon nitride fundamentally restricts its applications in second-order nonlinear optical processes.Monolayer transition metal dichalcogenides,particularly tungsten disulfide(WS_(2)),exhibit strong second-order nonlinear responses,making them ideal candidates for nonlinear photonic applications.Herein,we demonstrate a heterogeneously integrated platform combining silicon nitride waveguides with chemical vapor deposition(CVD)-grown monolayer WS_(2),enabling second harmonic generation.A specially designed silica cladding featuring gentle-slope profile on silicon nitride strip waveguides facilitates the integration of centimeter-scale WS_(2)film with photonic circuits.This approach provides a robust solution for incorporating second-order nonlinearity into silicon nitride photonic systems.The demonstrated platform holds significant potential for advancing quantum networks,visible-light lasers,and integrated optical modulation/detection systems.
