油浸式变压器中的微量水分严重影响着变压器的油纸绝缘性能,实现变压器中微量水分的在线监测至关重要。文中以水分子(H_(2)O)在NiO掺杂MoTe_(2)单层上的吸附结构、吸附能(E_(a))、电荷转移量(ΔQ)、态密度(DOS)、最高占据及最低未占据...油浸式变压器中的微量水分严重影响着变压器的油纸绝缘性能,实现变压器中微量水分的在线监测至关重要。文中以水分子(H_(2)O)在NiO掺杂MoTe_(2)单层上的吸附结构、吸附能(E_(a))、电荷转移量(ΔQ)、态密度(DOS)、最高占据及最低未占据分子轨道(HOMO⁃LUMO)、功函数(WF)和差分电荷密度(DCD)为计算对象,基于泛函密度函数理论(density function theory,DFT)计算研究了过渡金属氧化物(NiO)掺杂对单层MoTe_(2)吸附参数和电子性质的影响。结果表明:与本征单层MoTe_(2)相比,过渡金属氧化物(NiO)掺杂单层MoTe_(2)的化学活性明显增强。此外,NiO掺杂的单层MoTe_(2)对H_(2)O分子均表现出优异的吸附及解吸附能力。因此,基于NiO掺杂的单层MoTe_(2)气敏材料可进一步用于在油浸式变压器微量水分的在线监测领域。展开更多
The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising c...The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising candidates due to their built-in electric fields,ultrafast photocarrier separation,and tunable bandgaps,defect states limit their performance.Therefore,the modulation of the optoelectronic properties in such heterostructures is imperative.Surface charge transfer doping(SCTD)has emerged as a promising strategy for non-destructive modulation of electronic and optoelectronic characteristics in two-dimensional materials.In this work,we demonstrate the construction of high-performance p-i-n vertical heterojunction photodetectors through SCTD of MoTe_(2)/ReS_(2)heterostructure using p-type F_(4)-TCNQ.Systematic characterization reveals that the interfacial doping process effectively amplifies the built-in electric field,enhancing photogenerated carrier separation efficiency.Compared to the pristine heterojunction device,the doped photodetector exhibits remarkable visible to nearinfrared(635-1064 nm)performance.Particularly under 1064 nm illumination at zero bias,the device achieves a responsivity of 2.86 A/W and specific detectivity of 1.41×10^(12)Jones.Notably,the external quantum efficiency reaches an exceptional value of 334%compared to the initial 11.5%,while maintaining ultrafast response characteristics with rise/fall times of 11.6/15.6μs.This work provides new insights into interface engineering through molecular doping for developing high-performance vd W optoelectronic devices.展开更多
The two-dimensional(2D)material-based thermal switch is attracting attention due to its novel applications,such as energy conversion and thermal management,in nanoscale devices.In this paper,we observed that the rever...The two-dimensional(2D)material-based thermal switch is attracting attention due to its novel applications,such as energy conversion and thermal management,in nanoscale devices.In this paper,we observed that the reversible 2H–1T′phase transition in MoTe_(2)is associated with about a fourfold/tenfold change in thermal conductivity along the X/Y direction by using first-principles calculations.This phenomenon can be profoundly understood by comparing the Mo–Te bonding strength between the two phases.The 2H-MoTe_(2)has one stronger bonding type,while 1T′-MoTe_(2)has three weaker types of bonds,suggesting bonding inhomogeneity in 1T′-MoTe_(2).Meanwhile,the bonding inhomogeneity can induce more scattering of vibration modes.The weaker bonding indicates a softer structure,resulting in lower phonon group velocity,a shorter phonon relaxation lifetime and larger Gr¨uneisen constants.The impact caused by the 2H to 1T′phase transition in MoTe_(2)hinders the propagation of phonons,thereby reducing thermal conductivity.Our study describes the possibility for the provision of the MoTe_(2)-based controllable and reversible thermal switch device.展开更多
The direct synthesis of hydrogen peroxide(H_(2)O_(2))via a two‐electron oxygen reduction reaction(2e‐ORR)in acidic media has emerged as a green process for the production of this valuable chemical.However,such an ap...The direct synthesis of hydrogen peroxide(H_(2)O_(2))via a two‐electron oxygen reduction reaction(2e‐ORR)in acidic media has emerged as a green process for the production of this valuable chemical.However,such an approach employs expensive noble‐metal‐based electrocatalysts,which severely undermines its feasibility when implemented on an industrial scale.Herein,based on density functional theory computations and microkinetic modeling,we demonstrate that a novel two‐dimensional(2D)material,namely a 1T′‐MoTe_(2)monolayer,can serve as an efficient non‐precious electrocatalyst to facilitate the 2e‐ORR.The 1T′‐MoTe_(2)monolayer is a stable 2D crystal that can be easily produced through exfoliation techniques.The surface‐exposed Te sites of the 1T′‐MoTe_(2)monolayer exhibit a favorable OOH*binding energy of 4.24 eV,resulting in a rather high basal plane activity toward the 2e‐ORR.Importantly,kinetic computations indicate that the 1T'‐MoTe_(2)monolayer preferentially promotes the formation of H_(2)O_(2)over the competing four‐electron ORR step.These desirable characteristics render 1T′‐MoTe_(2)a promising candidate for catalyzing the electrochemical reduction of O_(2)to H_(2)O_(2).展开更多
MoTe_(2) has emerged as a promising candidate in the field of integrated circuits,memristive devices,and catalysts,owing to its polymorphic nature across different phases.Experimentally,strain engineering has been dem...MoTe_(2) has emerged as a promising candidate in the field of integrated circuits,memristive devices,and catalysts,owing to its polymorphic nature across different phases.Experimentally,strain engineering has been demonstrated as an effective approach for manipulating the phase transition of MoTe_(2),but the mechanism remains unclear.The strain-dependent phase transition and its micro-mechanisms have been investigated based on first principle calculations.As demonstrated,critical strain and phase transition path from H→T'phases are strongly governed by the applied strain's orientation,magnitude,and triaxiality.At the atomic level,nonzero movements of Te atoms within the phase transition domain with mechanical unloading have been clarified,together with an advanced understanding on the impact of strain on Te-vacancies migration.These insights advanced the knowledge of MoTe_(2) phase transition behavior and demonstrated the large space to explore potential applications through strain,defect,and phase engineering.展开更多
Two-dimensional(2D)MoTe_(2) shows great potential for future semiconductor devices,but the lab-to-fab transition is still in its preliminary stage due to the constraints in the crystal growth level.Currently,the chemi...Two-dimensional(2D)MoTe_(2) shows great potential for future semiconductor devices,but the lab-to-fab transition is still in its preliminary stage due to the constraints in the crystal growth level.Currently,the chemical vapor deposition growth of 2D MoTe_(2) primarily relies on the tellurization process of Mo-source precursor(MSP).However,the target product 2H-MoTe_(2) from Mo precursor suffers from long growth time and suboptimal crystal quality,and MoO_(x) precursor confronts the dilemma of unclear growth mechanism and inconsistent growth products.Here,we developed magnetron-sputtered MoO_(3) film for fast and high-mobility 2H-MoTe_(2) growth.The solid-to-solid phase transition growth mechanism of 2D MoTe_(2) from Mo and MoO_(x) precursor was first experimentally unified,and the effect mechanism of MSPs on 2D MoTe_(2) growth was systematically elucidated.Compared with Mo and MoO2,the MoO_(3) precursor has the least Mo-unit lattice deformation and exhibits the optimal crystal quality of growth products.Meanwhile,the lowest Gibbs free energy change of the chemical reaction results in an impressive 2HMoTe_(2) growth rate of 8.07 mm/min.The constructed 2H-MoTe_(2) field-effect transistor array from MoO_(3) precursor showcases record-high hole mobility of 85 cm^(2)·V^(-1)·s^(-1),competitive on-off ratio of 3×10^(4),and outstanding uniformity.This scalable method not only offers efficiency but also aligns with industry standards,making it a promising guideline for diverse 2D material preparation towards real-world applications.展开更多
Two-dimensional(2D)semiconductor-based junction field-effect transistors(JFETs)have emerged as vital architectures for next-generation low-power electronics due to their gate-dielectric-free structure and near-ideal s...Two-dimensional(2D)semiconductor-based junction field-effect transistors(JFETs)have emerged as vital architectures for next-generation low-power electronics due to their gate-dielectric-free structure and near-ideal subthreshold swing(SS)potential.Although doping strategies,such as defect engineering and chemical modification,can further enhance the performance of JFETs,complex techniques and uniformly-doping hinder their further applications.Here,we propose a lowpower MoS_(2)/MoTe_(2) JFET utilizing a pre-deposited Au film to dope the gate layer of MoTe_(2),which can uniformly increase the work function of MoTe_(2) and thus elevate heterostructure barrier heights.This method offers strong repeatability,avoids localized states on channel material,and is compatible with integrated circuit manufacturing.The JFETs achieve a near-ideal SS of 62.5 mV dec−1,mobility of 350 cm2 V−1 s−1,high current on/off ratio of 107,low gate leakage of 10−12 A,and low pinch-off voltage of−0.1 V.This strategy provides a universal and simple strategy for low-power circuits.展开更多
文摘油浸式变压器中的微量水分严重影响着变压器的油纸绝缘性能,实现变压器中微量水分的在线监测至关重要。文中以水分子(H_(2)O)在NiO掺杂MoTe_(2)单层上的吸附结构、吸附能(E_(a))、电荷转移量(ΔQ)、态密度(DOS)、最高占据及最低未占据分子轨道(HOMO⁃LUMO)、功函数(WF)和差分电荷密度(DCD)为计算对象,基于泛函密度函数理论(density function theory,DFT)计算研究了过渡金属氧化物(NiO)掺杂对单层MoTe_(2)吸附参数和电子性质的影响。结果表明:与本征单层MoTe_(2)相比,过渡金属氧化物(NiO)掺杂单层MoTe_(2)的化学活性明显增强。此外,NiO掺杂的单层MoTe_(2)对H_(2)O分子均表现出优异的吸附及解吸附能力。因此,基于NiO掺杂的单层MoTe_(2)气敏材料可进一步用于在油浸式变压器微量水分的在线监测领域。
基金financial support from 2024 Domestic Visiting Scholar Program for Teachers'Professional Development in Universities(Grant No.FX2024022)National Natural Science Foundation of China(Grant No.61904043)。
文摘The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising candidates due to their built-in electric fields,ultrafast photocarrier separation,and tunable bandgaps,defect states limit their performance.Therefore,the modulation of the optoelectronic properties in such heterostructures is imperative.Surface charge transfer doping(SCTD)has emerged as a promising strategy for non-destructive modulation of electronic and optoelectronic characteristics in two-dimensional materials.In this work,we demonstrate the construction of high-performance p-i-n vertical heterojunction photodetectors through SCTD of MoTe_(2)/ReS_(2)heterostructure using p-type F_(4)-TCNQ.Systematic characterization reveals that the interfacial doping process effectively amplifies the built-in electric field,enhancing photogenerated carrier separation efficiency.Compared to the pristine heterojunction device,the doped photodetector exhibits remarkable visible to nearinfrared(635-1064 nm)performance.Particularly under 1064 nm illumination at zero bias,the device achieves a responsivity of 2.86 A/W and specific detectivity of 1.41×10^(12)Jones.Notably,the external quantum efficiency reaches an exceptional value of 334%compared to the initial 11.5%,while maintaining ultrafast response characteristics with rise/fall times of 11.6/15.6μs.This work provides new insights into interface engineering through molecular doping for developing high-performance vd W optoelectronic devices.
基金the China Scholarship Council(Grant No.202107000030)RIE2020 Advanced Manufacturing and Engineering(AME)Programmatic(Grant No.A1898b0043)A*STAR Aerospace Programme(Grant No.M2115a0092)。
文摘The two-dimensional(2D)material-based thermal switch is attracting attention due to its novel applications,such as energy conversion and thermal management,in nanoscale devices.In this paper,we observed that the reversible 2H–1T′phase transition in MoTe_(2)is associated with about a fourfold/tenfold change in thermal conductivity along the X/Y direction by using first-principles calculations.This phenomenon can be profoundly understood by comparing the Mo–Te bonding strength between the two phases.The 2H-MoTe_(2)has one stronger bonding type,while 1T′-MoTe_(2)has three weaker types of bonds,suggesting bonding inhomogeneity in 1T′-MoTe_(2).Meanwhile,the bonding inhomogeneity can induce more scattering of vibration modes.The weaker bonding indicates a softer structure,resulting in lower phonon group velocity,a shorter phonon relaxation lifetime and larger Gr¨uneisen constants.The impact caused by the 2H to 1T′phase transition in MoTe_(2)hinders the propagation of phonons,thereby reducing thermal conductivity.Our study describes the possibility for the provision of the MoTe_(2)-based controllable and reversible thermal switch device.
文摘The direct synthesis of hydrogen peroxide(H_(2)O_(2))via a two‐electron oxygen reduction reaction(2e‐ORR)in acidic media has emerged as a green process for the production of this valuable chemical.However,such an approach employs expensive noble‐metal‐based electrocatalysts,which severely undermines its feasibility when implemented on an industrial scale.Herein,based on density functional theory computations and microkinetic modeling,we demonstrate that a novel two‐dimensional(2D)material,namely a 1T′‐MoTe_(2)monolayer,can serve as an efficient non‐precious electrocatalyst to facilitate the 2e‐ORR.The 1T′‐MoTe_(2)monolayer is a stable 2D crystal that can be easily produced through exfoliation techniques.The surface‐exposed Te sites of the 1T′‐MoTe_(2)monolayer exhibit a favorable OOH*binding energy of 4.24 eV,resulting in a rather high basal plane activity toward the 2e‐ORR.Importantly,kinetic computations indicate that the 1T'‐MoTe_(2)monolayer preferentially promotes the formation of H_(2)O_(2)over the competing four‐electron ORR step.These desirable characteristics render 1T′‐MoTe_(2)a promising candidate for catalyzing the electrochemical reduction of O_(2)to H_(2)O_(2).
基金supported by NSFC Grants(Nos.12032004,11872114,and 11502150)Natural Science Foundation of Hebei Province of China(No.A2016210060)+1 种基金The Higher Education Youth Talents Program of Hebei Province of China(No.BJ2017052)Science and Technology Project of Hebei Education Department(No.QN2020204)。
文摘MoTe_(2) has emerged as a promising candidate in the field of integrated circuits,memristive devices,and catalysts,owing to its polymorphic nature across different phases.Experimentally,strain engineering has been demonstrated as an effective approach for manipulating the phase transition of MoTe_(2),but the mechanism remains unclear.The strain-dependent phase transition and its micro-mechanisms have been investigated based on first principle calculations.As demonstrated,critical strain and phase transition path from H→T'phases are strongly governed by the applied strain's orientation,magnitude,and triaxiality.At the atomic level,nonzero movements of Te atoms within the phase transition domain with mechanical unloading have been clarified,together with an advanced understanding on the impact of strain on Te-vacancies migration.These insights advanced the knowledge of MoTe_(2) phase transition behavior and demonstrated the large space to explore potential applications through strain,defect,and phase engineering.
基金supported by the National Natural Science Foundation of China(Grant Nos.51991340,51991342,52225206,92163205,52188101,62322402,52350301,62204012,52250398,52303362,62304019)the National Key Research and Development Program of China(Grant No.2022YFA1203800,2022YFA1203803,2018YFA0703503,2023YFF1500400,2023YFF1500401)+7 种基金the Overseas Expertise Introduction Projects for Discipline Innovation(Grant No.B14003)the Frontier Cross Research Project of the Department of Chinese Academy of Sciences(Grant No.XK2023JSA001)the Beijing Nova Program(Grant No.20220484145,20230484478)the Young Elite Scientists sponsorship program by CAST(Grant No.2022QNRC001)the Fundamental Research Funds for the Central Universities(Grant No.FRF-06500207,FRF-TP-22-004C2,FRF-06500207,FRF-TP-22-004A1,FRF-IDRY-22-016)the State Key Lab for Advanced Metals andMaterials (No. 2023-Z05)Postdoctoral Fellowship Program of CPSF(GZC20230233)the Special support from the PostdoctoralScience Foundation (2023TQ0007).
文摘Two-dimensional(2D)MoTe_(2) shows great potential for future semiconductor devices,but the lab-to-fab transition is still in its preliminary stage due to the constraints in the crystal growth level.Currently,the chemical vapor deposition growth of 2D MoTe_(2) primarily relies on the tellurization process of Mo-source precursor(MSP).However,the target product 2H-MoTe_(2) from Mo precursor suffers from long growth time and suboptimal crystal quality,and MoO_(x) precursor confronts the dilemma of unclear growth mechanism and inconsistent growth products.Here,we developed magnetron-sputtered MoO_(3) film for fast and high-mobility 2H-MoTe_(2) growth.The solid-to-solid phase transition growth mechanism of 2D MoTe_(2) from Mo and MoO_(x) precursor was first experimentally unified,and the effect mechanism of MSPs on 2D MoTe_(2) growth was systematically elucidated.Compared with Mo and MoO2,the MoO_(3) precursor has the least Mo-unit lattice deformation and exhibits the optimal crystal quality of growth products.Meanwhile,the lowest Gibbs free energy change of the chemical reaction results in an impressive 2HMoTe_(2) growth rate of 8.07 mm/min.The constructed 2H-MoTe_(2) field-effect transistor array from MoO_(3) precursor showcases record-high hole mobility of 85 cm^(2)·V^(-1)·s^(-1),competitive on-off ratio of 3×10^(4),and outstanding uniformity.This scalable method not only offers efficiency but also aligns with industry standards,making it a promising guideline for diverse 2D material preparation towards real-world applications.
基金supported by the National Natural Science Foundation of China(52350301,52250398,92463308,62322402,52188101,52225206,92163205,62204012,52303362,62304019,52302162 and 52402169)the National Key Research and Development Program of China(2022YFA1203803,2024YFA1212600 and 2023YFF1500401)+5 种基金the Beijing Nova Program(20220484145 and 20230484478)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(2022QNRC001)the Fundamental Research Funds for the Central Universities(FRF-TP-22-004C2,FRF-06500207,FRF-TP-22-004A1,FRF-IDRY-22-016 and FRF-IDRY-23-038)the State Key Lab for Advanced Metals and Materials(2023-Z05)the Postdoctoral Fellowship Program of the China Postdoctoral Science Foudation(GZC20230233)the special support from the Postdoctoral Science Foundation(2023TQ0007).
文摘Two-dimensional(2D)semiconductor-based junction field-effect transistors(JFETs)have emerged as vital architectures for next-generation low-power electronics due to their gate-dielectric-free structure and near-ideal subthreshold swing(SS)potential.Although doping strategies,such as defect engineering and chemical modification,can further enhance the performance of JFETs,complex techniques and uniformly-doping hinder their further applications.Here,we propose a lowpower MoS_(2)/MoTe_(2) JFET utilizing a pre-deposited Au film to dope the gate layer of MoTe_(2),which can uniformly increase the work function of MoTe_(2) and thus elevate heterostructure barrier heights.This method offers strong repeatability,avoids localized states on channel material,and is compatible with integrated circuit manufacturing.The JFETs achieve a near-ideal SS of 62.5 mV dec−1,mobility of 350 cm2 V−1 s−1,high current on/off ratio of 107,low gate leakage of 10−12 A,and low pinch-off voltage of−0.1 V.This strategy provides a universal and simple strategy for low-power circuits.
