High-sensitivity room-temperature multi-dimensional infrared(IR)detection is crucial for military and civilian purposes.Recently,the gapless electronic structures and unique optoelectrical properties have made the two...High-sensitivity room-temperature multi-dimensional infrared(IR)detection is crucial for military and civilian purposes.Recently,the gapless electronic structures and unique optoelectrical properties have made the two-dimensional(2D)topological semimetals promising candidates for the realization of multifunctional optoelectronic devices.Here,we demonstrated the in-situ construction of high-performance 1T’-MoTe_(2)/Ge Schottky junction device by inserting an ultrathin AlOx passivation layer.The good detection performance with an ultra-broadband detection wavelength range of up to 10.6 micron,an ultrafast response time of~160 ns,and a large specific detectivity of over 109 Jones in mid-infrared(MIR)range surpasses that of most 2D materials-based IR sensors,approaching the performance of commercial IR photodiodes.The on-chip integrated device arrays with 64 functional detectors feature high-resolution imaging capability at room temperature.All these outstanding detection features have enabled the demonstration of position-sensitive detection applications.It demonstrates an exceptional position sensitivity of 14.9 mV/mm,an outstanding nonlinearity of 6.44%,and commendable trajectory tracking and optoelectronic demodulation capabilities.This study not only offers a promising route towards room-temperature MIR optoelectronic applications,but also demonstrates a great potential for application in optical sensing systems.展开更多
Two-dimensional(2D)transition metal dichalcogenides have been extensively studied due to their fascinating physical properties for constructing high-performance photodetectors.However,their relatively low responsiviti...Two-dimensional(2D)transition metal dichalcogenides have been extensively studied due to their fascinating physical properties for constructing high-performance photodetectors.However,their relatively low responsivities,current on/off ratios and response speeds have hindered their widespread application.Herein,we fabricated a high-performance photodetector based on few-layer MoTe_(2) and CdS_(0.42)Se_(0.58) flake heterojunctions.The photodetector exhibited a high responsivity of 7221 A/W,a large current on/off ratio of 1.73×10^(4),a fast response speed of 90/120μs,external quantum efficiency(EQE)reaching up to 1.52×10^(6)%and detectivity(D*)reaching up to 1.67×10^(15) Jones.The excellent performance of the heterojunction photodetector was analyzed by a photocurrent mapping test and first-principle calculations.Notably,the visible light imaging function was successfully attained on the MoTe_(2)/CdS_(0.42)Se_(0.58) photodetectors,indicating that the device had practical imaging application prospects.Our findings provide a reference for the design of ultrahighperformance MoTe_(2)-based photodetectors.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 interlayer friction behavior of two-dimensional transition metal dichalcogenides(TMDCs)as crucial solid lubricants has attracted extensive attention in the field of tribology.In this study,the interlayer friction ...The interlayer friction behavior of two-dimensional transition metal dichalcogenides(TMDCs)as crucial solid lubricants has attracted extensive attention in the field of tribology.In this study,the interlayer friction is measured by laterally pushing the MoTe_(2)powder on the MoTe_(2)substrate with the atomic force microscope(AFM)tip,and density functional theory(DFT)simulations are used to rationalize the experimental results.The experimental results indicate that the friction coefficient of the 1T'-MoTe_(2)/1T'-MoTe_(2)interface is 2.025×10^(−4),which is lower than that of the 2H-MoTe_(2)/2H-MoTe_(2)interface(3.086×10^(−4)),while the friction coefficient of the 1T'-MoTe_(2)/2H-MoTe_(2)interface is the lowest at 6.875×10^(−5).The lower interfacial friction of 1T'-MoTe_(2)/1T'-MoTe_(2)compared to 2H-MoTe_(2)/2H-MoTe_(2)interface can be explained by considering the relative magnitudes of the ideal average shear strengths and maximum shear strengths based on the interlayer potential energy.Additionally,the smallest interlayer friction observed at the 1T'-MoTe_(2)/2H-MoTe_(2)heterojunction is attributed to the weak interlayer electrostatic interaction and reduction in potential energy corrugation caused by the incommensurate contact.This work suggests that MoTe_(2)has comparable interlayer friction properties to MoS_(2)and is expected to reduce interlayer friction in the future by inducing the 2H-1T'phase transition.展开更多
Activating basal plane inert sites will endow MoTe_(2) with prominent hydrogen evolution reaction(HER)catalytic capability and arouse a new family of HER catalysts.Herein,we fabricated single MoTe_(2) sheet electrocat...Activating basal plane inert sites will endow MoTe_(2) with prominent hydrogen evolution reaction(HER)catalytic capability and arouse a new family of HER catalysts.Herein,we fabricated single MoTe_(2) sheet electrocatalytic microdevice for in situ revealing the activated basal plane sites by vacancies introducing.Through the extraction of electrical parameters of single MoTe_(2) sheet,the in-plane and interlayer conductivities were optimized effectively by Te vacancies due to the defect levels.More deeply,Te vacancies can induce the delocalization of electrons around Mo atoms and shift the d-band center,as a consequence,facilitate the adsorption of H from the catalyst surface for HER catalysis.Benefiting by the coordinated regulation of band structure and local charge density,the overpotential at−10 mA·cm^(−2)was reduced to 0.32 V after Te vacancies compared to 0.41 V for the basal plane sites of same MoTe_(2) nanosheet.Meanwhile,the insights gained from single nanosheet electrocatalytic microdevice can be applied to the improved HER of the commercial MoTe_(2) power.That the in situ testing of the atomic structure-electrical behavior-electrochemical properties of a single nanosheet before/after vacancies introducing provides reliable insight to structure-activity relationships.展开更多
Metastable 1T’MoTe_(2) has attracted much attention as a cost-effective electrocatalyst for hydrogen evolution reaction(HER)in recent years.However,few studies were done over common stable 2 H phase because it often ...Metastable 1T’MoTe_(2) has attracted much attention as a cost-effective electrocatalyst for hydrogen evolution reaction(HER)in recent years.However,few studies were done over common stable 2 H phase because it often exhibits inferior performance.Herein,stable 2H MoTe_(2) with S-doped Te vacancies has been synthesized by one-step telluride conversion of 1T MoS_(2) at 700℃under Ar/H_(2) atmosphere.It is demonstrated that the synergistic effect of S-doping and Te vacancies changes the electronic structures of the catalyst.Density functional theory(DFT)studies show that plentiful electrons accumulate on the surface S atoms in S-doped Te vacancies of 2H MoTe_(2) catalyst,which may be as active sites to promote HER.Moreover,the as-synthesized catalyst can be directly used as working electrode,and realizes current density of 100 mA cm^(-2) at overpotential of 217 mV with Tafel slope of 94 mV dec^(-1).This work stimulates intensive studies on the activation of inert phase of other nanocatalysts towards various reactions.展开更多
Spin orbit torques(SOTs)in ferromagnet/heavy-metal heterostructures have provided great opportunities for efficient manipulation of spintronic devices.However,deterministically field-free switching of perpendicular ma...Spin orbit torques(SOTs)in ferromagnet/heavy-metal heterostructures have provided great opportunities for efficient manipulation of spintronic devices.However,deterministically field-free switching of perpendicular magnetization with SOTs is forbidden because of the global two-fold rotational symmetry in conventional heavy-metal such as Pt.Here,we engineer the interface of Pt/Ni heterostructures by inserting a monolayer MoTe_(2)with low crystal symmetry.It is demonstrated that the spin orbit efficiency,as well as the out-of-plane magnetic anisotropy and the Gilbert damping of Ni are enhanced,due to the effect of orbital hybridization and the increased spin scatting at the interface induced by MoTe_(2).Particularly,an out-of-plane damping-like torque is observed when the current is applied perpendicular to the mirror plane of the MoTe_(2)crystal,which is attributed to the interfacial inversion symmetry breaking of the system.Our work provides an effective route for engineering the SOT in Pt-based heterostructures,and offers potential opportunities for van der Waals interfaces in spintronic devices.展开更多
The solar-to-hydrogen conversion using the photoelectrochemical(PEC)method is a practical approach to producing clean energy.However,it relies on the availability of photocatalyst materials.In this work,a novel photoc...The solar-to-hydrogen conversion using the photoelectrochemical(PEC)method is a practical approach to producing clean energy.However,it relies on the availability of photocatalyst materials.In this work,a novel photocatalyst comprising molybdenum telluride quantum dots(MoTe_(2) QDs)-modified titanium dioxide nanorods(TiO_(2) NRs)was prepared for the enhancement of the PEC water splitting performance after combination with a Al_(2)O_(3) layer using the atomic layer deposition(ALD)technique.MoTe_(2) QDs were initially prepared,and then they were loaded onto TiO_(2) NRs using a warm water bath-based heating method.After a layer of Al_(2)O_(3) was deposited onto resulted TiO_(2) NRs/MoTe_(2) QDs,the composite TiO_(2) NRs/MoTe_(2) QDs/Al_(2)O_(3) was finally obtained.Under simulated sunlight(100 mW·cm^(-2)),such a composite exhibited a maximum photocurrent density of 2.25 mA·cm^(-2) at 1.23 V(versus RHE)and an incident photon-to-electron conversion efficiency of 69.88%at 380 nm,which are 4.33 and 6.66 times those of pure TiO_(2) NRs,respectively.Therefore,the composite photocatalyst fabricated in this work may have promising application in the field of PEC water splitting,solarcells andotherphotocatalyticdevices.展开更多
Two-dimensional(2D)transition metal dichalcogenides(TMDCs)have layered structures with excellent tribological properties.Since the energy difference between hexagonal-molybdenum ditelluride(2H-MoTe_(2))and distorted o...Two-dimensional(2D)transition metal dichalcogenides(TMDCs)have layered structures with excellent tribological properties.Since the energy difference between hexagonal-molybdenum ditelluride(2H-MoTe_(2))and distorted octahedral-molybdenum ditelluride(1T′-MoTe_(2))is very small among the transition metal dichalcogenides(TMDCs),MoTe_(2) becomes one of the most promising candidates for phase engineering.In our experiment,we found that the friction force and friction coefficient(COF)of 2H-MoTe_(2) were an order of magnitude smaller than those of 1T′-MoTe_(2) by the atomic force microscope(AFM)experiments.The friction difference between 1T′-MoTe_(2) and 2H-MoTe_(2) was further verified in molecular dynamics(MD)simulations.The density functional theory(DFT)calculations suggest that the friction contrast is related to the difference in sliding energy barrier of the potential energy surface(PES)for a tip sliding across the surface.The PES obtained from the DFT calculation indicates that the maximum energy barrier and the minimum energy path(MEP)energy barrier of 2H-MoTe_(2) are both smaller than those of 1T′-MoTe_(2),which means that less energy needs to be dissipated during the sliding process.The difference in energy barrier of the PES could be ascribed to its larger interlayer spacing and weaker Mo–Te interatomic interactions within the layers of 2H-MoTe_(2) than those of 1T′-MoTe_(2).The obvious friction difference between 1T′-MoTe_(2) and 2H-MoTe_(2) not only provides a new non-destructive means to detect the phase transition by the AFM,but also provides a possibility to tune friction by controlling the phase transition,which has the potential to be applied in extreme environments such as space lubrication.展开更多
Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs wit...Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs with preferred crystal phases is crucial for their applications.Here,we demonstrate the epitaxial growth of 1T'-MoTe_(2) on Au(111)and graphitized silicon carbide(Gr/SiC)by molecular beam epitaxy(MBE).We investigate the morphology of the grown1T'-MoTe_(2) at the atomic level by scanning tunnelling microscopy(STM)and reveal the corresponding microscopic growth mechanism.It is found that the unique ordered Te structures preferentially deposited on Au(111)regulate the growth of monolayer single crystal 1T'-MoTe_(2),while the Mo clusters were preferentially deposited on the Gr/SiC substrate,which impedes the ordered growth of monolayer MoTe_(2).We confirm that the size of single crystal 1T'-MoTe_(2) grown on Au(111)is nearly two orders of magnitude larger than that on Gr/SiC.By scanning tunnelling spectroscopy(STS),we observe that the STS spectrum of the monolayer 1T'-MoTe_(2) nano-island at the edge is different from that at the interior,which exhibits enhanced conductivity.展开更多
Ultrathin transition metal dichalcogenides(TMDs)are of particular interest as low-cost alternatives to highly active electrocatalysts because of their high surface activation energy.However,their striking structural c...Ultrathin transition metal dichalcogenides(TMDs)are of particular interest as low-cost alternatives to highly active electrocatalysts because of their high surface activation energy.However,their striking structural characteristics cause chemical instability and undergo oxidation easily.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
基金the National Natural Science Foundation of China(Nos.U22A20138,62374149,and 62375279)the Collaborative Innovation Center of Suzhou Nano Science&Technology.The authors are grateful for the technical support from the Nano-X from Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences(SINANO).
文摘High-sensitivity room-temperature multi-dimensional infrared(IR)detection is crucial for military and civilian purposes.Recently,the gapless electronic structures and unique optoelectrical properties have made the two-dimensional(2D)topological semimetals promising candidates for the realization of multifunctional optoelectronic devices.Here,we demonstrated the in-situ construction of high-performance 1T’-MoTe_(2)/Ge Schottky junction device by inserting an ultrathin AlOx passivation layer.The good detection performance with an ultra-broadband detection wavelength range of up to 10.6 micron,an ultrafast response time of~160 ns,and a large specific detectivity of over 109 Jones in mid-infrared(MIR)range surpasses that of most 2D materials-based IR sensors,approaching the performance of commercial IR photodiodes.The on-chip integrated device arrays with 64 functional detectors feature high-resolution imaging capability at room temperature.All these outstanding detection features have enabled the demonstration of position-sensitive detection applications.It demonstrates an exceptional position sensitivity of 14.9 mV/mm,an outstanding nonlinearity of 6.44%,and commendable trajectory tracking and optoelectronic demodulation capabilities.This study not only offers a promising route towards room-temperature MIR optoelectronic applications,but also demonstrates a great potential for application in optical sensing systems.
基金This work was supported by the National Natural Science Foundation of China(Nos.11864046 and 11764046)the Basic Research Program of Yunnan Province(Nos.202001AT070064 and 202101AT070124)+1 种基金the Spring City Plan(Highlevel Talent Promotion and Training Project of Kunming)(No.2022SCP005)Yunnan Expert Workstation(No.202205AF150008).
文摘Two-dimensional(2D)transition metal dichalcogenides have been extensively studied due to their fascinating physical properties for constructing high-performance photodetectors.However,their relatively low responsivities,current on/off ratios and response speeds have hindered their widespread application.Herein,we fabricated a high-performance photodetector based on few-layer MoTe_(2) and CdS_(0.42)Se_(0.58) flake heterojunctions.The photodetector exhibited a high responsivity of 7221 A/W,a large current on/off ratio of 1.73×10^(4),a fast response speed of 90/120μs,external quantum efficiency(EQE)reaching up to 1.52×10^(6)%and detectivity(D*)reaching up to 1.67×10^(15) Jones.The excellent performance of the heterojunction photodetector was analyzed by a photocurrent mapping test and first-principle calculations.Notably,the visible light imaging function was successfully attained on the MoTe_(2)/CdS_(0.42)Se_(0.58) photodetectors,indicating that the device had practical imaging application prospects.Our findings provide a reference for the design of ultrahighperformance MoTe_(2)-based photodetectors.
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.
基金supported by the National Natural Science Foundation of China(No.52175175).
文摘The interlayer friction behavior of two-dimensional transition metal dichalcogenides(TMDCs)as crucial solid lubricants has attracted extensive attention in the field of tribology.In this study,the interlayer friction is measured by laterally pushing the MoTe_(2)powder on the MoTe_(2)substrate with the atomic force microscope(AFM)tip,and density functional theory(DFT)simulations are used to rationalize the experimental results.The experimental results indicate that the friction coefficient of the 1T'-MoTe_(2)/1T'-MoTe_(2)interface is 2.025×10^(−4),which is lower than that of the 2H-MoTe_(2)/2H-MoTe_(2)interface(3.086×10^(−4)),while the friction coefficient of the 1T'-MoTe_(2)/2H-MoTe_(2)interface is the lowest at 6.875×10^(−5).The lower interfacial friction of 1T'-MoTe_(2)/1T'-MoTe_(2)compared to 2H-MoTe_(2)/2H-MoTe_(2)interface can be explained by considering the relative magnitudes of the ideal average shear strengths and maximum shear strengths based on the interlayer potential energy.Additionally,the smallest interlayer friction observed at the 1T'-MoTe_(2)/2H-MoTe_(2)heterojunction is attributed to the weak interlayer electrostatic interaction and reduction in potential energy corrugation caused by the incommensurate contact.This work suggests that MoTe_(2)has comparable interlayer friction properties to MoS_(2)and is expected to reduce interlayer friction in the future by inducing the 2H-1T'phase transition.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21805102,22071069,and 21825103)the Hubei Provincial Natural Science Foundation of China(No.2019CFA002)the Foundation of Basic and Applied Basic Research of Guangdong Province(No.2019B1515120087)。
文摘Activating basal plane inert sites will endow MoTe_(2) with prominent hydrogen evolution reaction(HER)catalytic capability and arouse a new family of HER catalysts.Herein,we fabricated single MoTe_(2) sheet electrocatalytic microdevice for in situ revealing the activated basal plane sites by vacancies introducing.Through the extraction of electrical parameters of single MoTe_(2) sheet,the in-plane and interlayer conductivities were optimized effectively by Te vacancies due to the defect levels.More deeply,Te vacancies can induce the delocalization of electrons around Mo atoms and shift the d-band center,as a consequence,facilitate the adsorption of H from the catalyst surface for HER catalysis.Benefiting by the coordinated regulation of band structure and local charge density,the overpotential at−10 mA·cm^(−2)was reduced to 0.32 V after Te vacancies compared to 0.41 V for the basal plane sites of same MoTe_(2) nanosheet.Meanwhile,the insights gained from single nanosheet electrocatalytic microdevice can be applied to the improved HER of the commercial MoTe_(2) power.That the in situ testing of the atomic structure-electrical behavior-electrochemical properties of a single nanosheet before/after vacancies introducing provides reliable insight to structure-activity relationships.
基金supported by the National Natural Science Foundation of China(21771137)。
文摘Metastable 1T’MoTe_(2) has attracted much attention as a cost-effective electrocatalyst for hydrogen evolution reaction(HER)in recent years.However,few studies were done over common stable 2 H phase because it often exhibits inferior performance.Herein,stable 2H MoTe_(2) with S-doped Te vacancies has been synthesized by one-step telluride conversion of 1T MoS_(2) at 700℃under Ar/H_(2) atmosphere.It is demonstrated that the synergistic effect of S-doping and Te vacancies changes the electronic structures of the catalyst.Density functional theory(DFT)studies show that plentiful electrons accumulate on the surface S atoms in S-doped Te vacancies of 2H MoTe_(2) catalyst,which may be as active sites to promote HER.Moreover,the as-synthesized catalyst can be directly used as working electrode,and realizes current density of 100 mA cm^(-2) at overpotential of 217 mV with Tafel slope of 94 mV dec^(-1).This work stimulates intensive studies on the activation of inert phase of other nanocatalysts towards various reactions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51732010,51802341,and 12004415)the China Postdoctoral Science Foundation(Grant Nos.2020M671592,2019M661965)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20200255).
文摘Spin orbit torques(SOTs)in ferromagnet/heavy-metal heterostructures have provided great opportunities for efficient manipulation of spintronic devices.However,deterministically field-free switching of perpendicular magnetization with SOTs is forbidden because of the global two-fold rotational symmetry in conventional heavy-metal such as Pt.Here,we engineer the interface of Pt/Ni heterostructures by inserting a monolayer MoTe_(2)with low crystal symmetry.It is demonstrated that the spin orbit efficiency,as well as the out-of-plane magnetic anisotropy and the Gilbert damping of Ni are enhanced,due to the effect of orbital hybridization and the increased spin scatting at the interface induced by MoTe_(2).Particularly,an out-of-plane damping-like torque is observed when the current is applied perpendicular to the mirror plane of the MoTe_(2)crystal,which is attributed to the interfacial inversion symmetry breaking of the system.Our work provides an effective route for engineering the SOT in Pt-based heterostructures,and offers potential opportunities for van der Waals interfaces in spintronic devices.
基金supported by the National Natural Science Foundation of China(11904108)the“Pearl River Talent Recruitment Program”(2019ZT08X639)Guangdong Basic and Applied Basic Research Foundation(2024A1515030107).
基金The authors thank the National Natural Science Foundation of China(Grant Nos.52205230 and U21A2046)the Key Research and Development Program in Shandong Province(No.SYS202203)+4 种基金the Program for Taishan Scholars of Shandong Province(No.TS20190965)the Key Research Program of the Chinese Academy of Sciences(Grant No.ZDBS-ZRKJZ-TLCO10)the Western Light Project of CAS(xbzg-zdsys-202118)the Major Science and Technology Projects in Gansu Province(No.22ZD6GA002)the Major Program of the Lanzhou Institute of Chemical Physics,CAS(No.ZYFZFX-5)for providing financial support.
文摘The solar-to-hydrogen conversion using the photoelectrochemical(PEC)method is a practical approach to producing clean energy.However,it relies on the availability of photocatalyst materials.In this work,a novel photocatalyst comprising molybdenum telluride quantum dots(MoTe_(2) QDs)-modified titanium dioxide nanorods(TiO_(2) NRs)was prepared for the enhancement of the PEC water splitting performance after combination with a Al_(2)O_(3) layer using the atomic layer deposition(ALD)technique.MoTe_(2) QDs were initially prepared,and then they were loaded onto TiO_(2) NRs using a warm water bath-based heating method.After a layer of Al_(2)O_(3) was deposited onto resulted TiO_(2) NRs/MoTe_(2) QDs,the composite TiO_(2) NRs/MoTe_(2) QDs/Al_(2)O_(3) was finally obtained.Under simulated sunlight(100 mW·cm^(-2)),such a composite exhibited a maximum photocurrent density of 2.25 mA·cm^(-2) at 1.23 V(versus RHE)and an incident photon-to-electron conversion efficiency of 69.88%at 380 nm,which are 4.33 and 6.66 times those of pure TiO_(2) NRs,respectively.Therefore,the composite photocatalyst fabricated in this work may have promising application in the field of PEC water splitting,solarcells andotherphotocatalyticdevices.
基金supported by the National Natural Science Foundation of China(Grant No.52175175)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDC04000000).
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDCs)have layered structures with excellent tribological properties.Since the energy difference between hexagonal-molybdenum ditelluride(2H-MoTe_(2))and distorted octahedral-molybdenum ditelluride(1T′-MoTe_(2))is very small among the transition metal dichalcogenides(TMDCs),MoTe_(2) becomes one of the most promising candidates for phase engineering.In our experiment,we found that the friction force and friction coefficient(COF)of 2H-MoTe_(2) were an order of magnitude smaller than those of 1T′-MoTe_(2) by the atomic force microscope(AFM)experiments.The friction difference between 1T′-MoTe_(2) and 2H-MoTe_(2) was further verified in molecular dynamics(MD)simulations.The density functional theory(DFT)calculations suggest that the friction contrast is related to the difference in sliding energy barrier of the potential energy surface(PES)for a tip sliding across the surface.The PES obtained from the DFT calculation indicates that the maximum energy barrier and the minimum energy path(MEP)energy barrier of 2H-MoTe_(2) are both smaller than those of 1T′-MoTe_(2),which means that less energy needs to be dissipated during the sliding process.The difference in energy barrier of the PES could be ascribed to its larger interlayer spacing and weaker Mo–Te interatomic interactions within the layers of 2H-MoTe_(2) than those of 1T′-MoTe_(2).The obvious friction difference between 1T′-MoTe_(2) and 2H-MoTe_(2) not only provides a new non-destructive means to detect the phase transition by the AFM,but also provides a possibility to tune friction by controlling the phase transition,which has the potential to be applied in extreme environments such as space lubrication.
基金Project supported by the National Key R&D Program of China (Grant No.2022YFA1204302)the National Natural Science Foundation of China (Grant Nos.52022029,52221001,92263107,U23A20570,62090035,U19A2090,and 12174098)+1 种基金the Hunan Provincial Natural Science Foundation of China (Grant Nos.2022JJ30142 and 2019XK2001)in part supported by the State Key Laboratory of Powder Metallurgy,Central South University。
文摘Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs with preferred crystal phases is crucial for their applications.Here,we demonstrate the epitaxial growth of 1T'-MoTe_(2) on Au(111)and graphitized silicon carbide(Gr/SiC)by molecular beam epitaxy(MBE).We investigate the morphology of the grown1T'-MoTe_(2) at the atomic level by scanning tunnelling microscopy(STM)and reveal the corresponding microscopic growth mechanism.It is found that the unique ordered Te structures preferentially deposited on Au(111)regulate the growth of monolayer single crystal 1T'-MoTe_(2),while the Mo clusters were preferentially deposited on the Gr/SiC substrate,which impedes the ordered growth of monolayer MoTe_(2).We confirm that the size of single crystal 1T'-MoTe_(2) grown on Au(111)is nearly two orders of magnitude larger than that on Gr/SiC.By scanning tunnelling spectroscopy(STS),we observe that the STS spectrum of the monolayer 1T'-MoTe_(2) nano-island at the edge is different from that at the interior,which exhibits enhanced conductivity.
基金This work was supported financially by the National Natural Science Foundation of China(21805102,21825103,and 51727809)the National Basic Research Program of China(973 Program,2015CB932600).
文摘Ultrathin transition metal dichalcogenides(TMDs)are of particular interest as low-cost alternatives to highly active electrocatalysts because of their high surface activation energy.However,their striking structural characteristics cause chemical instability and undergo oxidation easily.
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).
