With the rapid advancement of science and technology,along with an increasing global focus on space exploration,there is a growing concern for addressing friction and wear issues in surface coatings for components ope...With the rapid advancement of science and technology,along with an increasing global focus on space exploration,there is a growing concern for addressing friction and wear issues in surface coatings for components operating in high-temperature environments within the aerospace sector.However,typical high-temperature coatings currently face challenges in effectively integrating excellent oxidation resistance,wear resistance,and lubrication properties in high-temperature settings.Studies have demonstrated the significant potential of Transition Metal Dichalcogenides(TMDCs)as lubricant additives in high-temperature lubrication,attributable to their distinctive crystal structures.Thus,this review concentrates on the compositional design of individual MX_(2)-type(M=W,Mo,Nb,Ta;X=S,Se)TMDCs(molybdenum disulfide(MoS_(2)),tungsten disulfide(WS2),niobium diselenide(NbSe_(2)),molybdenum diselenide(MoSe_(2)),tungsten diselenide(WSe_(2)))and their composites,including inorganic oxygen-containing sulfides,and explores the utilization of TMDCs in self-lubricating coatings.Furthermore,conventional preparation methods(mechanical exfoliation,liquid-phase ultrasonic exfoliation,chemical vapour deposition)for synthesizing TMDCs are outlined.Finally,an analysis of the lubrication mechanism of MX_(2)-type TMDCs is provided,along with future directions for enhancing the high-temperature lubrication performance of composite coatings.展开更多
单层过渡金属二卤代化合物(Transition Metal Dichalcogenides,TMDC)因其独特的光电性能在光电领域备受瞩目,但其在集成光电器件中的应用前景受到低量子产率的限制。镜上纳米粒子(nanoparticle-onmirror,NPoM)等离激元纳米腔与单层TMDC...单层过渡金属二卤代化合物(Transition Metal Dichalcogenides,TMDC)因其独特的光电性能在光电领域备受瞩目,但其在集成光电器件中的应用前景受到低量子产率的限制。镜上纳米粒子(nanoparticle-onmirror,NPoM)等离激元纳米腔与单层TMDC集成,可以调节光和物质间的相互作用,增强荧光发射。这种纳米腔的光学质量深受作为镜面基底的沉积金属膜粗糙度引起的光学损耗影响,因此本文以自制的超光滑单晶金微米片作为镜面基底,设计了一种低损耗的NPo M纳米腔实现对单层二硒化钨(WSe_(2))荧光的增强。使用原子力显微镜与共聚焦显微镜相结合的实验系统,对纳米腔进行原位荧光探测。实验结果显示,制备的纳米腔可以高效调制WSe_(2)的荧光特性,在室温下单层WSe_(2)-NPoM混合体系中观察到高达1189倍的荧光增强,且实现了45%的高偏振发射。通过时域有限差分法理论模拟,证实腔体能有效提高单层WSe2的光激发速率、量子产率和荧光收集效率。我们的研究结果为实现低成本、高效率的非线性光子器件提供了可行的方案。展开更多
Two-dimensional(2D)transition metal dichalcogenide(TMDC)monolayers,a class of ultrathin materials with a direct bandgap and high exciton binding energies,provide an ideal platform to study the photoluminescence(PL)of ...Two-dimensional(2D)transition metal dichalcogenide(TMDC)monolayers,a class of ultrathin materials with a direct bandgap and high exciton binding energies,provide an ideal platform to study the photoluminescence(PL)of light-emitting devices.Atomically thin TMDCs usually contain various defects,which enrich the lattice structure and give rise to many intriguing properties.As the influences of defects can be either detrimental or beneficial,a comprehensive understanding of the internal mechanisms underlying defect behaviour is required for PL tailoring.Herein,recent advances in the defect influences on PL emission are summarized and discussed.Fundamental mechanisms are the focus of this review,such as radiative/nonradiative recombination kinetics and band structure modification.Both challenges and opportunities are present in the field of defect manipulation,and the exploration of mechanisms is expected tofacilitate the applications of 2D TMDCs in the future.展开更多
Transition metal dichalcogenides(TMDCs)have suitable and adjustable band gaps,high carrier mobility and yield.Layered TMDCs have attracted great attention due to the structure diversity,stable existence in normal temp...Transition metal dichalcogenides(TMDCs)have suitable and adjustable band gaps,high carrier mobility and yield.Layered TMDCs have attracted great attention due to the structure diversity,stable existence in normal temperature environment and the band gap corresponding to wavelength between infrared and visible region.The ultra-thin,flat,almost defect-free surface,excellent mechanical flexibility and chemical stability provide convenient conditions for the construction of different types of TMDCs heterojunctions.The optoelectric properties of heterojunctions based on TMDCs materials are summarized in this review.Special electronic band structures of TMDCs heterojunctions lead to excellent optoelectric properties.The emitter,p-n diodes,photodetectors and photosensitive devices based on TMDCs heterojunction materials show excellent performance.These devices provide a prototype for the design and development of future high-performance optoelectric devices.展开更多
This paper uses an innovative improved artificial bee colony(IABC)algorithm to aid in the fabrication of a highly responsive phasemodulation surface plasmon resonance(SPR)biosensor.In this biosensor’s sensing structu...This paper uses an innovative improved artificial bee colony(IABC)algorithm to aid in the fabrication of a highly responsive phasemodulation surface plasmon resonance(SPR)biosensor.In this biosensor’s sensing structure,a double-layer Ag-Au metal film is combined with a blue phosphorene/transition metal dichalcogenide(BlueP/TMDC)hybrid structure and graphene.In the optimization function of the IABC method,the reflectivity at resonance angle is incorporated as a constraint to achieve high phase sensitivity.The performance of the Ag-Au-BlueP/TMDC-graphene heterostructure as optimized by the IABC method is compared with that of a similar structure optimized using the traditional ABC algorithm.The results indicate that optimization using the IABC method gives significantly more phase sensitivity,together with lower reflectivity,than can be achieved with the traditional ABC method.The highest phase sensitivity of 3.662×10^(6) °/RIU is achieved with a bilayer of BlueP/WS2 and three layers of graphene.Moreover,analysis of the electric field distribution demonstrates that the optimal arrangement can be utilized for enhanced detection of small biomolecules.Thus,given the exceptional sensitivity achieved,the proposed method based on the IABC algorithm has great promise for use in the design of high-performance SPR biosensors with a variety of multilayer structures.展开更多
Transition metal dichalcogenide(TMDC)monolayers provide an ideal platform for exciton and valley-spintronics exploration due to their unique properties.Integrating TMDC monolayers with conventional semiconductors allo...Transition metal dichalcogenide(TMDC)monolayers provide an ideal platform for exciton and valley-spintronics exploration due to their unique properties.Integrating TMDC monolayers with conventional semiconductors allows for harnessing the unique properties of both materials.This strategy holds great promise for the development of advanced optoelectronics and spintronic devices.In this work,we investigated exciton and valley dynamics in WSe_(2)/Ga As heterostructure by employing the femtosecond pump-probe ultrafast spectroscopy.Facilitated by the charge transfer within the heterostructure,it was found that the exciton of WSe_(2)exhibited much longer lifetime of nanosecond than that of the WSe_(2)monolayer counterpart.Especially,a significantly long valley lifetime up to~2.7 ns was observed for trions of WSe_(2)in the heterostructure even under the off-resonant excitation,which is found to be associated with the resident electrons accumulated at the interface resulting from the charge transfer and resultant interfacial electric field.Our results provide fundamental references for conventional semiconductor-integrated TMDC heterostructures that have great potential for designing novel optoelectronic and spintronic devices.展开更多
Water electrolysis for green hydrogen production is important for the global carbon neutrality.The industrialization of this technology requires efficient and durable electrocatalysts under high-current-density(HCD)op...Water electrolysis for green hydrogen production is important for the global carbon neutrality.The industrialization of this technology requires efficient and durable electrocatalysts under high-current-density(HCD)operations.However,the insufficient mass and charge transfer at the various interfaces lead to unsatisfactory HCD activity and durability.Interface engineering is important for designing efficient HCD electrocatalysts.In this perspective,we analyze the processes taking place at three interfaces including the catalyst-substrate,catalyst-electrolyte,and catalyst-gas interfaces,and reveal the correlations between interface interactions and the challenges for HCD electrolysis.We then highlight the development of HCD electrocatalysts that focus on interface engineering using the example of transition metal dichalcogenide based catalysts,which have attracted widespread interests in recent years.Finally,we give an outlook on the development of interface engineering for the industrialization of water electrolysis technology.展开更多
Electrocatalytic water splitting for hydrogen production is an appealing strategy to reduce carbon emissions and generate renewable fuels.This promising process,however,is limited by its sluggish reaction kinetics and...Electrocatalytic water splitting for hydrogen production is an appealing strategy to reduce carbon emissions and generate renewable fuels.This promising process,however,is limited by its sluggish reaction kinetics and high-cost catalysts.The two-dimensional(2D)transition metal dichalcogenides(TMDCs)have presented great potential as electrocatalytic materials due to their tunable bandgaps,abundant defective active sites,and good chemical stability.Consequently,phase engineering,defect engineering and interface engineering have been adopted to manipulate the electronic structure of TMDCs for boosting their exceptional catalytic performance.Particularly,it is essential to clarify the local structure of catalytically active sites of TMDCs and their structural evolution in catalytic reactions using atomic resolution electron microscopy and the booming in situ technologies,which is beneficial for exploring the underlying reaction mechanism.In this review,the growth regulation,characterization,particularly atomic configurations of active sites in TMDCs are summarized.The significant role of electron microscopy in the understanding of the growth mechanism,the controlled synthesis and functional optimization of 2D TMDCs are discussed.This review will shed light on the design and synthesis of novel electrocatalysts with high performance,as well as prompt the application of advanced electron microscopy in the research of materials science.展开更多
Spintronics,exploiting the spin degree of electrons as the information vector,is an attractive field for implementing the beyond Complemetary metal-oxide-semiconductor(CMOS)devices.Recently,two-dimensional(2D)material...Spintronics,exploiting the spin degree of electrons as the information vector,is an attractive field for implementing the beyond Complemetary metal-oxide-semiconductor(CMOS)devices.Recently,two-dimensional(2D)materials have been drawing tremendous attention in spintronics owing to their distinctive spin-dependent properties,such as the ultralong spin relaxation time of graphene and the spin-valley locking of transition metal dichalcogenides.Moreover,the related heterostructures provide an unprecedented probability of combining the di erent characteristics via proximity e ect,which could remedy the limitation of individual 2D materials.Hence,the proximity engineering has been growing extremely fast and has made significant achievements in the spin injection and manipulation.Nevertheless,there are still challenges toward practical application;for example,the mechanism of spin relaxation in 2D materials is unclear,and the high-effciency spin gating is not yet achieved.In this review,we focus on 2D materials and related heterostructures to systematically summarize the progress of the spin injection,transport,manipulation,and application for information storage and processing.We also highlight the current challenges and future perspectives on the studies of spintronic devices based on 2D materials.展开更多
Two-dimensional(2D)transition metal dichalcogenides(TMDCs)have attracted growing interest regarding their potential applications in next-generation electronic and optoelectronic devices.Owing to their atomic thickness...Two-dimensional(2D)transition metal dichalcogenides(TMDCs)have attracted growing interest regarding their potential applications in next-generation electronic and optoelectronic devices.Owing to their atomic thickness and tunable bandgap,they exhibit unique mechanical,electrical,and optical properties.As a specific member of the TMDC family,rhenium disulfide(ReS_(2))has stimulated intensive interest due to its anisotropic crystal structure,weak inter-layer coupling,and anisotropic electrical and optical properties.In this review,we summarize the distinct crystal structure and intrinsic anisotropic properties of ReS_(2),followed by an introduction to its synthesis methods.The current applications of ReS_(2)and its heterojunctions are presented based on its anisotropic properties.This review not only provides a timely summary of the current applications of ReS_(2)and its heterojunctions,but also inspires new approaches to develop other innovative devices based on 2D materials with a low lattice symmetry.展开更多
Monolayer transition-metal dichacolgenides (TMDCs) present a direct optical bandgap at the Brillouin zones, socalled valleys. Those energetically degenerate valleys (K and K’) present different valley pseudospins, em...Monolayer transition-metal dichacolgenides (TMDCs) present a direct optical bandgap at the Brillouin zones, socalled valleys. Those energetically degenerate valleys (K and K’) present different valley pseudospins, emitting the valley photons with opposite spin angular momentums due to nonlinear optical selection rules. Furthermore, although atomically thin, two-dimensional (2D) TMDCs have giant nonlinearity, which can be enhanced by the valley-excitons.展开更多
Atomically thin transition metal dichalcogenide films with distorted trigonal(1T') phase have been predicted to be candidates for realizing quantum spin Hall effect. Growth of 1T' film and experimental investi...Atomically thin transition metal dichalcogenide films with distorted trigonal(1T') phase have been predicted to be candidates for realizing quantum spin Hall effect. Growth of 1T' film and experimental investigation of its electronic structure are critical. Here we report the electronic structure of 1T'-MoTe2 films grown by molecular beam epitaxy(MBE).Growth of the 1T'-MoTe2 film depends critically on the substrate temperature, and successful growth of the film is indicated by streaky stripes in the reflection high energy electron diffraction(RHEED) and sharp diffraction spots in the low energy electron diffraction(LEED). Angle-resolved photoemission spectroscopy(ARPES) measurements reveal a metallic behavior in the as-grown film with an overlap between the conduction and valence bands. First principles calculation suggests that a suitable tensile strain along the a-axis direction is needed to induce a gap to make it an insulator. Our work not only reports the electronic structure of MBE grown 1T'-MoTe2 films, but also provides insights for strain engineering to make it possible for quantum spin Hall effect.展开更多
Monolayer transition-metal dichalcogenides possess rich excitonic physics and unique valley-contrasting optical selection rule,and offer a great platform for long spin/valley lifetime engineering and the associated sp...Monolayer transition-metal dichalcogenides possess rich excitonic physics and unique valley-contrasting optical selection rule,and offer a great platform for long spin/valley lifetime engineering and the associated spin/valleytronics exploration.Using two-color time-resolved Kerr rotation and time-resolved reflectivity spectroscopy,we investigate the spin/valley dynamics of different excitonic states in monolayer WSe_(2)grown by molecular beam epitaxy.With fine tuning of the photon energy of both pump and probe beams,the valley relaxation process for the neutral excitons and trions is found to be remarkably different-their characteristic spin/valley lifetimes vary from picoseconds to nanoseconds,respectively.The observed long trion spin lifetime of>2.0 ns is discussed to be associated with the dark trion states,which is evidenced by the photon-energy dependent valley polarization relaxation.Our results also reveal that valley depolarization for these different excitonic states is intimately connected with the strong Coulomb interaction when the optical excitation energy is above the exciton resonance.展开更多
Two-dimensional(2D) materials have attracted extensive interest due to their excellent electrical, thermal,mechanical, and optical properties. Graphene has been one of the most explored 2D materials. However, its zero...Two-dimensional(2D) materials have attracted extensive interest due to their excellent electrical, thermal,mechanical, and optical properties. Graphene has been one of the most explored 2D materials. However, its zero band gap has limited its applications in electronic devices. Transition metal dichalcogenide(TMDC), another kind of 2D material,has a nonzero direct band gap(same charge carrier momentum in valence and conduction band) at monolayer state,promising for the efficient switching devices(e.g., field-effect transistors). This review mainly focuses on the recent advances in charge carrier mobility and the challenges to achieve high mobility in the electronic devices based on 2DTMDC materials and also includes an introduction of 2D materials along with the synthesis techniques. Finally, this review describes the possible methodology and future prospective to enhance the charge carrier mobility for electronic devices.展开更多
文摘With the rapid advancement of science and technology,along with an increasing global focus on space exploration,there is a growing concern for addressing friction and wear issues in surface coatings for components operating in high-temperature environments within the aerospace sector.However,typical high-temperature coatings currently face challenges in effectively integrating excellent oxidation resistance,wear resistance,and lubrication properties in high-temperature settings.Studies have demonstrated the significant potential of Transition Metal Dichalcogenides(TMDCs)as lubricant additives in high-temperature lubrication,attributable to their distinctive crystal structures.Thus,this review concentrates on the compositional design of individual MX_(2)-type(M=W,Mo,Nb,Ta;X=S,Se)TMDCs(molybdenum disulfide(MoS_(2)),tungsten disulfide(WS2),niobium diselenide(NbSe_(2)),molybdenum diselenide(MoSe_(2)),tungsten diselenide(WSe_(2)))and their composites,including inorganic oxygen-containing sulfides,and explores the utilization of TMDCs in self-lubricating coatings.Furthermore,conventional preparation methods(mechanical exfoliation,liquid-phase ultrasonic exfoliation,chemical vapour deposition)for synthesizing TMDCs are outlined.Finally,an analysis of the lubrication mechanism of MX_(2)-type TMDCs is provided,along with future directions for enhancing the high-temperature lubrication performance of composite coatings.
文摘单层过渡金属二卤代化合物(Transition Metal Dichalcogenides,TMDC)因其独特的光电性能在光电领域备受瞩目,但其在集成光电器件中的应用前景受到低量子产率的限制。镜上纳米粒子(nanoparticle-onmirror,NPoM)等离激元纳米腔与单层TMDC集成,可以调节光和物质间的相互作用,增强荧光发射。这种纳米腔的光学质量深受作为镜面基底的沉积金属膜粗糙度引起的光学损耗影响,因此本文以自制的超光滑单晶金微米片作为镜面基底,设计了一种低损耗的NPo M纳米腔实现对单层二硒化钨(WSe_(2))荧光的增强。使用原子力显微镜与共聚焦显微镜相结合的实验系统,对纳米腔进行原位荧光探测。实验结果显示,制备的纳米腔可以高效调制WSe_(2)的荧光特性,在室温下单层WSe_(2)-NPoM混合体系中观察到高达1189倍的荧光增强,且实现了45%的高偏振发射。通过时域有限差分法理论模拟,证实腔体能有效提高单层WSe2的光激发速率、量子产率和荧光收集效率。我们的研究结果为实现低成本、高效率的非线性光子器件提供了可行的方案。
基金the National Key R&D Program of China(Nos.2017YFA 0205700,2019YFA 0308000)the National Natural Science Foundation of China(NSFC)(Nos.61774034,91963130,11704068,61705106)Jiangsu Natural Science Foundation(No.BK20170694).The project is supported by"the Fundamental Research Funds for the Central Universities"。
文摘Two-dimensional(2D)transition metal dichalcogenide(TMDC)monolayers,a class of ultrathin materials with a direct bandgap and high exciton binding energies,provide an ideal platform to study the photoluminescence(PL)of light-emitting devices.Atomically thin TMDCs usually contain various defects,which enrich the lattice structure and give rise to many intriguing properties.As the influences of defects can be either detrimental or beneficial,a comprehensive understanding of the internal mechanisms underlying defect behaviour is required for PL tailoring.Herein,recent advances in the defect influences on PL emission are summarized and discussed.Fundamental mechanisms are the focus of this review,such as radiative/nonradiative recombination kinetics and band structure modification.Both challenges and opportunities are present in the field of defect manipulation,and the exploration of mechanisms is expected tofacilitate the applications of 2D TMDCs in the future.
基金supported by the National Natural Science Foundation of China(Grant Nos.91436102 and 11374353)and the Fundamental Research Funds for the Central Universities(Grant No.06500067).
文摘Transition metal dichalcogenides(TMDCs)have suitable and adjustable band gaps,high carrier mobility and yield.Layered TMDCs have attracted great attention due to the structure diversity,stable existence in normal temperature environment and the band gap corresponding to wavelength between infrared and visible region.The ultra-thin,flat,almost defect-free surface,excellent mechanical flexibility and chemical stability provide convenient conditions for the construction of different types of TMDCs heterojunctions.The optoelectric properties of heterojunctions based on TMDCs materials are summarized in this review.Special electronic band structures of TMDCs heterojunctions lead to excellent optoelectric properties.The emitter,p-n diodes,photodetectors and photosensitive devices based on TMDCs heterojunction materials show excellent performance.These devices provide a prototype for the design and development of future high-performance optoelectric devices.
基金funded by the National Natural Science Foundation of China(Grant No.52375547)the Natural Science Foundation of Chongqing,China(Grant Nos.CSTB2022NSCQ-BHX0736 and CSTB2022NSCQ-MSX1523)the Chongqing Scientific Institution Incentive Performance Guiding Special Projects(Grant No.CSTB2024JXJL-YFX0034).
文摘This paper uses an innovative improved artificial bee colony(IABC)algorithm to aid in the fabrication of a highly responsive phasemodulation surface plasmon resonance(SPR)biosensor.In this biosensor’s sensing structure,a double-layer Ag-Au metal film is combined with a blue phosphorene/transition metal dichalcogenide(BlueP/TMDC)hybrid structure and graphene.In the optimization function of the IABC method,the reflectivity at resonance angle is incorporated as a constraint to achieve high phase sensitivity.The performance of the Ag-Au-BlueP/TMDC-graphene heterostructure as optimized by the IABC method is compared with that of a similar structure optimized using the traditional ABC algorithm.The results indicate that optimization using the IABC method gives significantly more phase sensitivity,together with lower reflectivity,than can be achieved with the traditional ABC method.The highest phase sensitivity of 3.662×10^(6) °/RIU is achieved with a bilayer of BlueP/WS2 and three layers of graphene.Moreover,analysis of the electric field distribution demonstrates that the optimal arrangement can be utilized for enhanced detection of small biomolecules.Thus,given the exceptional sensitivity achieved,the proposed method based on the IABC algorithm has great promise for use in the design of high-performance SPR biosensors with a variety of multilayer structures.
基金funded by the National Key Research and Development Program of China(Grant No.2022YFA1405100)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB43000000)。
文摘Transition metal dichalcogenide(TMDC)monolayers provide an ideal platform for exciton and valley-spintronics exploration due to their unique properties.Integrating TMDC monolayers with conventional semiconductors allows for harnessing the unique properties of both materials.This strategy holds great promise for the development of advanced optoelectronics and spintronic devices.In this work,we investigated exciton and valley dynamics in WSe_(2)/Ga As heterostructure by employing the femtosecond pump-probe ultrafast spectroscopy.Facilitated by the charge transfer within the heterostructure,it was found that the exciton of WSe_(2)exhibited much longer lifetime of nanosecond than that of the WSe_(2)monolayer counterpart.Especially,a significantly long valley lifetime up to~2.7 ns was observed for trions of WSe_(2)in the heterostructure even under the off-resonant excitation,which is found to be associated with the resident electrons accumulated at the interface resulting from the charge transfer and resultant interfacial electric field.Our results provide fundamental references for conventional semiconductor-integrated TMDC heterostructures that have great potential for designing novel optoelectronic and spintronic devices.
文摘Water electrolysis for green hydrogen production is important for the global carbon neutrality.The industrialization of this technology requires efficient and durable electrocatalysts under high-current-density(HCD)operations.However,the insufficient mass and charge transfer at the various interfaces lead to unsatisfactory HCD activity and durability.Interface engineering is important for designing efficient HCD electrocatalysts.In this perspective,we analyze the processes taking place at three interfaces including the catalyst-substrate,catalyst-electrolyte,and catalyst-gas interfaces,and reveal the correlations between interface interactions and the challenges for HCD electrolysis.We then highlight the development of HCD electrocatalysts that focus on interface engineering using the example of transition metal dichalcogenide based catalysts,which have attracted widespread interests in recent years.Finally,we give an outlook on the development of interface engineering for the industrialization of water electrolysis technology.
基金the National Natural Science Foundation of China(Grant Nos.U21A20174 and 52001222)the Science and Technology Innovation Talent Team Project of Shanxi Province(Grant No.202304051001010)+3 种基金the Key National Scientific and Technological Co-operation Projects of Shanxi Province(Grant No.202104041101008)the Natural Science Foundation of Shanxi Province(Grant No.202303021221045)the Program for the Innovative Talents of Higher Education Institutions of Shanxi(PTIT)and the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(STIP)(Grant No.2022L036).
文摘Electrocatalytic water splitting for hydrogen production is an appealing strategy to reduce carbon emissions and generate renewable fuels.This promising process,however,is limited by its sluggish reaction kinetics and high-cost catalysts.The two-dimensional(2D)transition metal dichalcogenides(TMDCs)have presented great potential as electrocatalytic materials due to their tunable bandgaps,abundant defective active sites,and good chemical stability.Consequently,phase engineering,defect engineering and interface engineering have been adopted to manipulate the electronic structure of TMDCs for boosting their exceptional catalytic performance.Particularly,it is essential to clarify the local structure of catalytically active sites of TMDCs and their structural evolution in catalytic reactions using atomic resolution electron microscopy and the booming in situ technologies,which is beneficial for exploring the underlying reaction mechanism.In this review,the growth regulation,characterization,particularly atomic configurations of active sites in TMDCs are summarized.The significant role of electron microscopy in the understanding of the growth mechanism,the controlled synthesis and functional optimization of 2D TMDCs are discussed.This review will shed light on the design and synthesis of novel electrocatalysts with high performance,as well as prompt the application of advanced electron microscopy in the research of materials science.
基金partially supported by the National Natural Science Foundation of China(Grant No.61775241)the Youth Innovation Team(Grant No:2019012)of CSU+3 种基金the Hunan province key research and development project(Grant No:2019GK2233)Hunan Province Graduate Research and Innovation Project(Grant No:CX20190177)the Science and Technology Innovation Basic Research Project of Shenzhen(Grant No.JCYJ20180307151237242)the funding support from the Australian Research Council(ARC Discovery Project,DP180102976).
文摘Spintronics,exploiting the spin degree of electrons as the information vector,is an attractive field for implementing the beyond Complemetary metal-oxide-semiconductor(CMOS)devices.Recently,two-dimensional(2D)materials have been drawing tremendous attention in spintronics owing to their distinctive spin-dependent properties,such as the ultralong spin relaxation time of graphene and the spin-valley locking of transition metal dichalcogenides.Moreover,the related heterostructures provide an unprecedented probability of combining the di erent characteristics via proximity e ect,which could remedy the limitation of individual 2D materials.Hence,the proximity engineering has been growing extremely fast and has made significant achievements in the spin injection and manipulation.Nevertheless,there are still challenges toward practical application;for example,the mechanism of spin relaxation in 2D materials is unclear,and the high-effciency spin gating is not yet achieved.In this review,we focus on 2D materials and related heterostructures to systematically summarize the progress of the spin injection,transport,manipulation,and application for information storage and processing.We also highlight the current challenges and future perspectives on the studies of spintronic devices based on 2D materials.
基金financially supported by the National Natural Science Foundation of China(Nos.11974041 and12034002)the Fundamental Research Funds for the Central Universities(No.FRF-IDRY-19-007)。
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDCs)have attracted growing interest regarding their potential applications in next-generation electronic and optoelectronic devices.Owing to their atomic thickness and tunable bandgap,they exhibit unique mechanical,electrical,and optical properties.As a specific member of the TMDC family,rhenium disulfide(ReS_(2))has stimulated intensive interest due to its anisotropic crystal structure,weak inter-layer coupling,and anisotropic electrical and optical properties.In this review,we summarize the distinct crystal structure and intrinsic anisotropic properties of ReS_(2),followed by an introduction to its synthesis methods.The current applications of ReS_(2)and its heterojunctions are presented based on its anisotropic properties.This review not only provides a timely summary of the current applications of ReS_(2)and its heterojunctions,but also inspires new approaches to develop other innovative devices based on 2D materials with a low lattice symmetry.
文摘Monolayer transition-metal dichacolgenides (TMDCs) present a direct optical bandgap at the Brillouin zones, socalled valleys. Those energetically degenerate valleys (K and K’) present different valley pseudospins, emitting the valley photons with opposite spin angular momentums due to nonlinear optical selection rules. Furthermore, although atomically thin, two-dimensional (2D) TMDCs have giant nonlinearity, which can be enhanced by the valley-excitons.
基金Project supported by the National Basic Research Program of China(Grant Nos.2016YFA0301004 and 2015CB921001)the National Natural Science Foundation of China(Grant Nos.11334006,11725418,and 11674188)
文摘Atomically thin transition metal dichalcogenide films with distorted trigonal(1T') phase have been predicted to be candidates for realizing quantum spin Hall effect. Growth of 1T' film and experimental investigation of its electronic structure are critical. Here we report the electronic structure of 1T'-MoTe2 films grown by molecular beam epitaxy(MBE).Growth of the 1T'-MoTe2 film depends critically on the substrate temperature, and successful growth of the film is indicated by streaky stripes in the reflection high energy electron diffraction(RHEED) and sharp diffraction spots in the low energy electron diffraction(LEED). Angle-resolved photoemission spectroscopy(ARPES) measurements reveal a metallic behavior in the as-grown film with an overlap between the conduction and valence bands. First principles calculation suggests that a suitable tensile strain along the a-axis direction is needed to induce a gap to make it an insulator. Our work not only reports the electronic structure of MBE grown 1T'-MoTe2 films, but also provides insights for strain engineering to make it possible for quantum spin Hall effect.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB43000000).
文摘Monolayer transition-metal dichalcogenides possess rich excitonic physics and unique valley-contrasting optical selection rule,and offer a great platform for long spin/valley lifetime engineering and the associated spin/valleytronics exploration.Using two-color time-resolved Kerr rotation and time-resolved reflectivity spectroscopy,we investigate the spin/valley dynamics of different excitonic states in monolayer WSe_(2)grown by molecular beam epitaxy.With fine tuning of the photon energy of both pump and probe beams,the valley relaxation process for the neutral excitons and trions is found to be remarkably different-their characteristic spin/valley lifetimes vary from picoseconds to nanoseconds,respectively.The observed long trion spin lifetime of>2.0 ns is discussed to be associated with the dark trion states,which is evidenced by the photon-energy dependent valley polarization relaxation.Our results also reveal that valley depolarization for these different excitonic states is intimately connected with the strong Coulomb interaction when the optical excitation energy is above the exciton resonance.
基金funded by Australian Research Council discovery project DP140103041Future Fellowship FT160100205
文摘Two-dimensional(2D) materials have attracted extensive interest due to their excellent electrical, thermal,mechanical, and optical properties. Graphene has been one of the most explored 2D materials. However, its zero band gap has limited its applications in electronic devices. Transition metal dichalcogenide(TMDC), another kind of 2D material,has a nonzero direct band gap(same charge carrier momentum in valence and conduction band) at monolayer state,promising for the efficient switching devices(e.g., field-effect transistors). This review mainly focuses on the recent advances in charge carrier mobility and the challenges to achieve high mobility in the electronic devices based on 2DTMDC materials and also includes an introduction of 2D materials along with the synthesis techniques. Finally, this review describes the possible methodology and future prospective to enhance the charge carrier mobility for electronic devices.
