We report on the formation of two-dimensional monolayer AgTe crystal on Ag(111)substrates.The samples are prepared in ultrahigh vacuum by deposition of Te on Ag(111)followed by annealing.Using a scanning tunneling mic...We report on the formation of two-dimensional monolayer AgTe crystal on Ag(111)substrates.The samples are prepared in ultrahigh vacuum by deposition of Te on Ag(111)followed by annealing.Using a scanning tunneling microscope(STM)and low electron energy diffraction(LEED),we investigate the atomic structure of the samples.The STM images and the LEED pattern show that monolayer AgTe crystal is formed on Ag(111).Four kinds of atomic structures of AgTe and Ag(111)are observed:(i)flat honeycomb structure,(ii)bulked honeycomb,(iii)stripe structure,(iv)hexagonal structure.The structural analysis indicates that the formation of the different atomic structures is due to the lattice mismatch and relief of the intrinsic strain in the AgTe layer.Our results provide a simple and convenient method to produce monolayer AgTe atomic crystal on Ag(111)and a template for study of novel physical properties and for future quantum devices.展开更多
Crystal structure prediction(CSP)is a foundational computational technique for determining the atomic arrangements of crystalline materials,especially under high-pressure conditions.While CSP plays a critical role in ...Crystal structure prediction(CSP)is a foundational computational technique for determining the atomic arrangements of crystalline materials,especially under high-pressure conditions.While CSP plays a critical role in materials science,traditional approaches often encounter significant challenges related to computational efficiency and scalability,particularly when applied to complex systems.Recent advances in machine learning(ML)have shown tremendous promise in addressing these limitations,enabling the rapid and accurate prediction of crystal structures across a wide range of chemical compositions and external conditions.This review provides a concise overview of recent progress in ML-assisted CSP methodologies,with a particular focus on machine learning potentials and generative models.By critically analyzing these advances,we highlight the transformative impact of ML in accelerating materials discovery,enhancing computational efficiency,and broadening the applicability of CSP.Additionally,we discuss emerging opportunities and challenges in this rapidly evolving field.展开更多
Facing the growing data storage and computing demands, a high accessing speed memory with low power and non- volatile character is urgently needed. Resistive access random memory with 4F2 cell size, switching in sub-n...Facing the growing data storage and computing demands, a high accessing speed memory with low power and non- volatile character is urgently needed. Resistive access random memory with 4F2 cell size, switching in sub-nanosecond, cycling endurances of over 1012 cycles, and information retention exceeding 10 years, is considered as promising next- generation non-volatile memory. However, the energy per bit is still too high to compete against static random access memory and dynamic random access memory. The sneak leakage path and metal film sheet resistance issues hinder the further scaling down. The variation of resistance between different devices and even various cycles in the same device, hold resistive access random memory back from commercialization. The emerging of atomic crystals, possessing fine interface without dangling bonds in low dimension, can provide atomic level solutions for the obsessional issues. Moreover, the unique properties of atomic crystals also enable new type resistive switching memories, which provide a brand-new direction for the resistive access random memory.展开更多
Since their emergence,Two-Dimensional(2D)materials have garnered significant attention due to their unique crystal structures and electronic properties,which offer distinct advantages for various applications.As a res...Since their emergence,Two-Dimensional(2D)materials have garnered significant attention due to their unique crystal structures and electronic properties,which offer distinct advantages for various applications.As a result,the study of 2D materials has become a crucial area within materials science.This paper introduces four representative 2D materials:graphene,hexagonal boron nitride,two-dimensional transition metal dichalcogenides,and phosphorene.It also briefly discusses their applications in electronic and optoelectronic devices,batteries,supercapacitors,and photocatalytic reactions,analyzing the advantages they hold over traditional materials.展开更多
Organometallic nanosheets are a versatile platform for design of efficient electrocatalyst materials due to their high surface area and uniform dispersion of metal active sites.In this paper,we systematically investig...Organometallic nanosheets are a versatile platform for design of efficient electrocatalyst materials due to their high surface area and uniform dispersion of metal active sites.In this paper,we systematically investigate the electrocatalytic performance of the first transition metal series TM3–C12S12 monolayers on CO_(2)using spin-polarized density functional theory.The calculations show that M3–C12S12 exhibits excellent catalytic activity and selectivity in the catalytic reduction in CO_(2).The main reduction products of Sc,Ti,and Cr are CH4.V,Mn,Fe and Zn mainly produce HCOOH,and Co produces HCHO,while CO is the main product for Ni and Cu.For Sc,Ti,and Cr,the overpotentials are>0.7 V,while for V,Mn,Fe,Co,Ni,Cu,Zn,the overpotentials are very low and range from 0.27 to 0.47 V.Therefore,our results indicate that many of the M3–C12S12 monolayers are expected to be excellent and efficient CO_(2)reduction catalysts.展开更多
Surface-sensitive measurements are crucial to many types of researches in condensed matter physics.However,it is difficult to obtain atomically flat surfaces of many single crystals by the commonly used mechanical cle...Surface-sensitive measurements are crucial to many types of researches in condensed matter physics.However,it is difficult to obtain atomically flat surfaces of many single crystals by the commonly used mechanical cleavage.We demonstrate that the grind-polish-sputter-anneal method can be used to obtain atomically flat surfaces on topological materials.Three types of surface-sensitive measurements are performed on CoSi(001)surface with dramatically improved quality of data.This method extends the research area of surface-sensitive measurements to hard-to-cleave alloys,and can be applied to irregular single crystals with selective crystalline planes.It may become a routine process of preparing atomically flat surfaces for surface-sensitive technologies.展开更多
The object is to investigate the wear of an atomic force microscope (AFM) diamond tip when conducting micro/nano machining on single crystal silicon surface. The experimental research and theoretical analysis were car...The object is to investigate the wear of an atomic force microscope (AFM) diamond tip when conducting micro/nano machining on single crystal silicon surface. The experimental research and theoretical analysis were carried out on the worn tip in terms of wear rate, wear mechanism and the effect of the tip wear on micro machining process. The wear rate was calculated as 1.7(10～10mm 3/(N·m) by using a theoretical model combined with the experimental results. Through an integration of an AFM observation on the worn tip features with the FEM simulation of the stress distribution, in addition to the unit cutting force calculation on the AFM diamond tip, the wear mechanism of the AFM diamond tip was concluded as mainly chemical wear, and the wear process was also elaborated as well.展开更多
Scanning probe microscopy(SPM)allows the spatial imaging,measurement,and manipulation of nano and atomic scale surfaces in real space.In the last two decades,numerous advanced and functional SPM methods,particularly a...Scanning probe microscopy(SPM)allows the spatial imaging,measurement,and manipulation of nano and atomic scale surfaces in real space.In the last two decades,numerous advanced and functional SPM methods,particularly atomic force microscopy(AFM),have been developed and applied in various research fields,from mapping sample morphology to measuring physical properties.Herein,we review the recent progress in functional AFM methods and their applications in studies of two-dimensional(2D)materials,particularly their interfacial physical properties on the substrates.This review can inspire more exciting application works using advanced AFM modes in the 2D and functional materials fields.展开更多
Self-template transformations are widely used for preparation of lanthanide(Ln^(3+))based nanoparticles with tunable porosity and composition,considering of their outstanding performance in optical,drug delivery and b...Self-template transformations are widely used for preparation of lanthanide(Ln^(3+))based nanoparticles with tunable porosity and composition,considering of their outstanding performance in optical,drug delivery and bioimaging.However,it is still a major challenge to characterize the crystallization process,morphology and composition changes of these nanostructures in atomic scale and three-dimensional(3D).In this paper,we investigate the transformation of amorphous precursor to porous Y_(2)O_(3):Eu^(3+)nanocrystals with advanced microscopy techniques.The morphology changes and compositions under different temperatures are identified through in-situ microscopy.The porous structures in 3D is clearly studied via electron tomography.Insights from this research are of broader interest for the class of transformation reactions,which will definitely shed light on the synthesis of complex nanostructures.展开更多
It is the nature of crystals to exist in different polymorphs. The recent emergence of two-dimensional(2 D) materials has evoked the discovery of a number of new crystal phases that are different from their bulk struc...It is the nature of crystals to exist in different polymorphs. The recent emergence of two-dimensional(2 D) materials has evoked the discovery of a number of new crystal phases that are different from their bulk structures at ambient conditions, and revealed novel structure-dependent properties, which deserve in-depth understanding and further exploration. In this contribution, we review the recent development of crystal phase control in 2 D materials, including group V and VI. transition metal dichalcogenides(TMDs), group IVA metal chalcogenides and noble metals. For each group of materials, we begin with introducing the various existing crystal phases and their structure-related properties, followed by a detailed discussion on factors that influence these crystal structures and thus the possible strategies for phase control. Finally, after summarizing the whole paper, we present the challenges and opportunities in this research direction.展开更多
We use laser-scanning nonlinear imaging microscopy in atomically thin transition metal dichalcogenides(TMDs)to reveal information on the crystalline orientation distribution,within the 2D lattice.In particular,we perf...We use laser-scanning nonlinear imaging microscopy in atomically thin transition metal dichalcogenides(TMDs)to reveal information on the crystalline orientation distribution,within the 2D lattice.In particular,we perform polarization-resolved second-harmonic generation(PSHG)imaging in a stationary,raster-scanned chemical vapor deposition(CVD)-grown WS2 flake,in order to obtain with high precision a spatially resolved map of the orientation of its main crystallographic axis(armchair orientation).By fitting the experimental PSHG images of sub-micron resolution into a generalized nonlinear model,we are able to determine the armchair orientation for every pixel of the image of the 2D material,with further improved resolution.This pixel-wise mapping of the armchair orientation of 2D WS2 allows us to distinguish between different domains,reveal fine structure,and estimate the crystal orientation variability,which can be used as a unique crystal quality marker over large areas.The necessity and superiority of a polarization-resolved analysis over intensity-only measurements is experimentally demonstrated,while the advantages of PSHG over other techniques are analysed and discussed.展开更多
Ammonia borane(NH_(3)BH_(3),AB)has been considered to be a promising chemical hydrogen storage material.Based on density functional theory,a series of transition metal atoms supported P_(3)C(P_(3)C_O)sheet is systemat...Ammonia borane(NH_(3)BH_(3),AB)has been considered to be a promising chemical hydrogen storage material.Based on density functional theory,a series of transition metal atoms supported P_(3)C(P_(3)C_O)sheet is systematically investigated to screen out the most promising catalyst for dehydrogenation of AB.The results indicate that the Os/P_(3)C and Os/P_(3)C_O could be an efficient single atom catalyst(SACs)and the stepwise reaction pathway with free energy barrier of 2.07 and 1.54 e V respectively.Remarkably,the rate constant further quantitatively confirmed the real situation of the first step of dehydrogenation of AB on the Os/P_(3)C and Os/P_(3)C_O substrates.We found that k_(f1)at 400 K is equivalent to k_(f2)at 800 K,which greatly improves the temperature of the first step of AB dehydrogenation on P_(3)C_O.We hope this work can provide a promising method for the design of catalysts for AB dehydrogenation reactions on the surface of two-dimensional materials(2D).展开更多
Atomically thin two-dimensional(2D)materials exhibit enormous potential in photodetectors because of novel and extraordinary properties,such as passivated surfaces,tunable bandgaps,and high mobility.High-performance p...Atomically thin two-dimensional(2D)materials exhibit enormous potential in photodetectors because of novel and extraordinary properties,such as passivated surfaces,tunable bandgaps,and high mobility.High-performance photodetectors based on 2D materials have been fabricated for broadband,position,polarization-sensitive detection,and large-area array imaging.However,the current performance of 2D material photodetectors is not outstanding enough,including response speed,detectivity,and so forth.The way to further promote the development of 2D material photodetectors and their corresponding practical applications is still a tremendous challenge.In this article,these issues of 2D material photodetectors are analyzed and expected to be solved by combining micro-nano characterization technologies.The inherent physical properties of 2D materials and photodetectors can be accurately characterized by Raman spectroscopy,transmission electron microscopy(TEM),and scattering scanning near-field optical microscope(s-SNOM).In particular,the precise probe of lattice defects,doping concentration,and near-field light absorption characteristics can promote the researches of low-noise and high-responsivity photodetectors.Scanning photocurrent microscope(SPCM)can show the overall spatial distribution of photocurrent and analyze the mechanism of photocurrent.Photoluminescence(PL)spectroscopy and Kelvin probe force microscope(KPFM)can characterize the material bandgap,work function distribution and interlayer coupling characteristics,making it possible to design high-performance photodetectors through energy band engineering.These advanced characterization techniques cover the entire process from material growth,to device preparation,and to performance analysis,and systematically reveal the development status of 2D material photodetectors.Finally,the prospects and challenges are discussed to promote the application of 2D material photodetectors.展开更多
Two-dimensional single-crystalline p-n junctions of organic semiconductors(pn-2 DCOSs) show great potential in organic logic circuits due to their single crystal nature and excellent ambipolar charge transport. Howeve...Two-dimensional single-crystalline p-n junctions of organic semiconductors(pn-2 DCOSs) show great potential in organic logic circuits due to their single crystal nature and excellent ambipolar charge transport. However,there are only few reports on pn-2 DCOSs because it is difficult to obtain such highly ordered structure in p-n junction.Herein, a novel and effective solution processing method of secondary transfer technology based on the facile drop casting is used to fabricate devices of pn-2 DCOSs based on C8-BTBT(p-type) and TFT-CN(n-type) successfully. The high-performance ambipolar field transistors based on such ultrathin pn-2 DCOSs with several molecular layers thickness show wellbalanced ambipolar charge transport behaviors with hole mobility as high as 0.43 cm^2 V^-1 s^-1 and electron mobility up to 0.11 cm^2 V^-1 s(^-1), respectively. This work is essential for studying the intrinsic properties of organic p-n junctions and achieving high performance in organic complementary circuits.展开更多
Among the various two-dimensional(2D)materials,more than 99%of them are noncentrosymmetric.However,since the commonly used substrates are generally centrosymmetric,antiparallel islands are usually inevitable in the gr...Among the various two-dimensional(2D)materials,more than 99%of them are noncentrosymmetric.However,since the commonly used substrates are generally centrosymmetric,antiparallel islands are usually inevitable in the growth of noncentrosymmetric 2D materials because of the energetic equivalency of these two kinds of antiparallel islands on centrosymmetric substrates.Therefore,achieving the growth of noncentrosymmetric 2D single crystals has long been a great challenge compared with the centrosymmetric ones like graphene.In this review,we presented the remarkable efforts and progress in the past decade,through precise chemical processes.We first discussed the great challenge and possible strategies in the growth of noncentrosymmetric 2D single crystals.Then,we focused on the advancements made in producing representative noncentrosymmetric 2D single crystals,including hexagonal boron nitride(hBN),transition metal dichalcogenides(TMDs),and other noncentrosymmetric 2D materials.At last,we summarized and looked forward to future research on the growth of layer-,stacking-,and twist-controlled noncentrosymmetric 2D single crystals and their heterostructures.展开更多
Giant tunneling magnetoresistance(TMR)has always been a pursuit in the research of magnetic tunnel junctions(MTJ).Two-dimensional(2D)magnetic materials have been used to construct lateral MTJ with high TMR.Here we inv...Giant tunneling magnetoresistance(TMR)has always been a pursuit in the research of magnetic tunnel junctions(MTJ).Two-dimensional(2D)magnetic materials have been used to construct lateral MTJ with high TMR.Here we investigated the crystal structure and magnetic property of CrSI monolayer,and found that it is a ferromagnetic semiconductor with a Curie temperature of about 180 K.The CrSI monolayer with Li adsorption(Li-CrSI)show ferromagnetic half-metallic with a high Curie temperature of 300 K.Further we designed a lateral Li CrSI/CrSI/Li-CrSI monolayer MTJ.The TMR of the MTJs along b transport direction is 3 orders of magnitude times larger than that of the a transport direction,which should result from the different spin filtering ability along the two directions.The TMR of b transport direction in the MTJ is 7.67×10^(14),which is significantly higher than that of any reported lateral MTJs based on 2D materials.Our results provide a promising avenue for designing lateral MTJs with giant TMR and high Curie temperature.展开更多
It is suggested that there is a kind of probability wave of the atomic configuration p(R)in crystals that can be deduced from the eigenequation of the ionic interaction Hamiltonian,and it has definite physical meaning...It is suggested that there is a kind of probability wave of the atomic configuration p(R)in crystals that can be deduced from the eigenequation of the ionic interaction Hamiltonian,and it has definite physical meaning. By use of the probability wave of the atomic con-figuration, the occupation probabilities of different kinds of atoms at lattice sites in multi-component solutions can be studied, and the crystal structures of multi-component solutionscan be predicted.展开更多
Atomically precise coordination nanoclusters(NCs)constitute a pivotal and rapidly advancing domain in the realms of materials science and chemistry owing to their distinctive crystal structures and exceptional attribu...Atomically precise coordination nanoclusters(NCs)constitute a pivotal and rapidly advancing domain in the realms of materials science and chemistry owing to their distinctive crystal structures and exceptional attributes encompassing molecular magnetism[1],photoluminescence[2],and catalysis[3].Organic ligands play a crucial role in effectively shielding these NCs,serving two primary functions:firstly,vital in preventing NC aggregation,particularly for the formation of robust single-crystal structures;secondly,acting as either bridging or peripheral structural components of NCs[4].This characterization of organic-inorganic hybridization offers unique advantages for unraveling the intricate relationships between structure and properties[5].展开更多
基金Supported by the National Key Research&Development Projects of China under Grant Nos 2016YFA0202300 and 2018FYA0305800the National Natural Science Foundation of China under Grant Nos 61390501,61474141 and 11604373+1 种基金the CAS Pioneer Hundred Talents Programthe Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDB28000000
文摘We report on the formation of two-dimensional monolayer AgTe crystal on Ag(111)substrates.The samples are prepared in ultrahigh vacuum by deposition of Te on Ag(111)followed by annealing.Using a scanning tunneling microscope(STM)and low electron energy diffraction(LEED),we investigate the atomic structure of the samples.The STM images and the LEED pattern show that monolayer AgTe crystal is formed on Ag(111).Four kinds of atomic structures of AgTe and Ag(111)are observed:(i)flat honeycomb structure,(ii)bulked honeycomb,(iii)stripe structure,(iv)hexagonal structure.The structural analysis indicates that the formation of the different atomic structures is due to the lattice mismatch and relief of the intrinsic strain in the AgTe layer.Our results provide a simple and convenient method to produce monolayer AgTe atomic crystal on Ag(111)and a template for study of novel physical properties and for future quantum devices.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1402304)the National Natural Science Foundation of China(Grant Nos.12034009,12374005,52288102,52090024,and T2225013)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Program for JLU Science and Technology Innovative Research Team.
文摘Crystal structure prediction(CSP)is a foundational computational technique for determining the atomic arrangements of crystalline materials,especially under high-pressure conditions.While CSP plays a critical role in materials science,traditional approaches often encounter significant challenges related to computational efficiency and scalability,particularly when applied to complex systems.Recent advances in machine learning(ML)have shown tremendous promise in addressing these limitations,enabling the rapid and accurate prediction of crystal structures across a wide range of chemical compositions and external conditions.This review provides a concise overview of recent progress in ML-assisted CSP methodologies,with a particular focus on machine learning potentials and generative models.By critically analyzing these advances,we highlight the transformative impact of ML in accelerating materials discovery,enhancing computational efficiency,and broadening the applicability of CSP.Additionally,we discuss emerging opportunities and challenges in this rapidly evolving field.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61376093 and 61622401)the National Key Research and Development Program of China(Grant No.2016YFA0203900)
文摘Facing the growing data storage and computing demands, a high accessing speed memory with low power and non- volatile character is urgently needed. Resistive access random memory with 4F2 cell size, switching in sub-nanosecond, cycling endurances of over 1012 cycles, and information retention exceeding 10 years, is considered as promising next- generation non-volatile memory. However, the energy per bit is still too high to compete against static random access memory and dynamic random access memory. The sneak leakage path and metal film sheet resistance issues hinder the further scaling down. The variation of resistance between different devices and even various cycles in the same device, hold resistive access random memory back from commercialization. The emerging of atomic crystals, possessing fine interface without dangling bonds in low dimension, can provide atomic level solutions for the obsessional issues. Moreover, the unique properties of atomic crystals also enable new type resistive switching memories, which provide a brand-new direction for the resistive access random memory.
文摘Since their emergence,Two-Dimensional(2D)materials have garnered significant attention due to their unique crystal structures and electronic properties,which offer distinct advantages for various applications.As a result,the study of 2D materials has become a crucial area within materials science.This paper introduces four representative 2D materials:graphene,hexagonal boron nitride,two-dimensional transition metal dichalcogenides,and phosphorene.It also briefly discusses their applications in electronic and optoelectronic devices,batteries,supercapacitors,and photocatalytic reactions,analyzing the advantages they hold over traditional materials.
基金support from the National Natural Science Foundation of China(21673087 and 21873032)startup fund(2006013118 and 3004013105)from Huazhong University of Science and Technologythe Fundamental Research Funds for the Central Universities(2019kfy R CPY116)
文摘Organometallic nanosheets are a versatile platform for design of efficient electrocatalyst materials due to their high surface area and uniform dispersion of metal active sites.In this paper,we systematically investigate the electrocatalytic performance of the first transition metal series TM3–C12S12 monolayers on CO_(2)using spin-polarized density functional theory.The calculations show that M3–C12S12 exhibits excellent catalytic activity and selectivity in the catalytic reduction in CO_(2).The main reduction products of Sc,Ti,and Cr are CH4.V,Mn,Fe and Zn mainly produce HCOOH,and Co produces HCHO,while CO is the main product for Ni and Cu.For Sc,Ti,and Cr,the overpotentials are>0.7 V,while for V,Mn,Fe,Co,Ni,Cu,Zn,the overpotentials are very low and range from 0.27 to 0.47 V.Therefore,our results indicate that many of the M3–C12S12 monolayers are expected to be excellent and efficient CO_(2)reduction catalysts.
基金Project supported by the Science Fund from the Ministry of Science and Technology of China(Grant Nos.2016YFA0401000,2016YFA0300600,2016YFA0302400,2016YFA0300504,and 2017YFA0302901)the National Natural Science Foundation of China(Grant Nos.11622435,U1832202,11474340,11822412,11574371,11674369,11574394,11774423,and 11774399)+4 种基金the Fund from the Chinese Academy of Sciences(Grant Nos.QYZDB-SSW-SLH043,XDB07000000,and XDB28000000)the Science Challenge Project,China(Grant No.TZ2016004)the K C Wong Education Foundation,China(Grant No.GJTD-2018-01)the Beijing Natural Science Foundation,China(Grant No.Z180008),the Fund from the Beijing Municipal Science and Technology Commission,China(Grant Nos.Z171100002017018,Z181100004218005,and Z181100004218001)the Fundamental Research Funds for the Central Universities,China,and the Research Funds of Renmin University of China(Grant Nos.15XNLQ07,18XNLG14,and 19XNLG17).
文摘Surface-sensitive measurements are crucial to many types of researches in condensed matter physics.However,it is difficult to obtain atomically flat surfaces of many single crystals by the commonly used mechanical cleavage.We demonstrate that the grind-polish-sputter-anneal method can be used to obtain atomically flat surfaces on topological materials.Three types of surface-sensitive measurements are performed on CoSi(001)surface with dramatically improved quality of data.This method extends the research area of surface-sensitive measurements to hard-to-cleave alloys,and can be applied to irregular single crystals with selective crystalline planes.It may become a routine process of preparing atomically flat surfaces for surface-sensitive technologies.
文摘The object is to investigate the wear of an atomic force microscope (AFM) diamond tip when conducting micro/nano machining on single crystal silicon surface. The experimental research and theoretical analysis were carried out on the worn tip in terms of wear rate, wear mechanism and the effect of the tip wear on micro machining process. The wear rate was calculated as 1.7(10～10mm 3/(N·m) by using a theoretical model combined with the experimental results. Through an integration of an AFM observation on the worn tip features with the FEM simulation of the stress distribution, in addition to the unit cutting force calculation on the AFM diamond tip, the wear mechanism of the AFM diamond tip was concluded as mainly chemical wear, and the wear process was also elaborated as well.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61911540074,61674045,11604063,11622437,11974422,and 12172047)the Ministry of Science and Technology(MOST)of China(Nos.2016YFA0200700 and 2018YFE0202700)+1 种基金the support of the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(No.XDB30000000)Z H C and W J received Fundamental Research Funds for the Central Universities and Research Funds of Renmin University of China(Nos.21XNLG27 and 19XNQ025).
文摘Scanning probe microscopy(SPM)allows the spatial imaging,measurement,and manipulation of nano and atomic scale surfaces in real space.In the last two decades,numerous advanced and functional SPM methods,particularly atomic force microscopy(AFM),have been developed and applied in various research fields,from mapping sample morphology to measuring physical properties.Herein,we review the recent progress in functional AFM methods and their applications in studies of two-dimensional(2D)materials,particularly their interfacial physical properties on the substrates.This review can inspire more exciting application works using advanced AFM modes in the 2D and functional materials fields.
基金financially supported by the National Natural Science Foundation of China(No.52002357)
文摘Self-template transformations are widely used for preparation of lanthanide(Ln^(3+))based nanoparticles with tunable porosity and composition,considering of their outstanding performance in optical,drug delivery and bioimaging.However,it is still a major challenge to characterize the crystallization process,morphology and composition changes of these nanostructures in atomic scale and three-dimensional(3D).In this paper,we investigate the transformation of amorphous precursor to porous Y_(2)O_(3):Eu^(3+)nanocrystals with advanced microscopy techniques.The morphology changes and compositions under different temperatures are identified through in-situ microscopy.The porous structures in 3D is clearly studied via electron tomography.Insights from this research are of broader interest for the class of transformation reactions,which will definitely shed light on the synthesis of complex nanostructures.
基金supported by the Joint Research Fund for Overseas Chinese, Hong Kong and Macao Scholars (51528201)the MOE under AcRF Tier 2 (ARC 19/15, MOE2014-T2-2-093, MOE2015-T22-057, MOE2016-T2-2-103, MOE2017-T2-1-162)+1 种基金AcRF Tier 1 (2016-T1001-147, 2016-T1-002-051, 2017-T1-001-150, 2017-T1-002-119)NTU under Start-Up Grant (M4081296.070.500000) in Singapore
文摘It is the nature of crystals to exist in different polymorphs. The recent emergence of two-dimensional(2 D) materials has evoked the discovery of a number of new crystal phases that are different from their bulk structures at ambient conditions, and revealed novel structure-dependent properties, which deserve in-depth understanding and further exploration. In this contribution, we review the recent development of crystal phase control in 2 D materials, including group V and VI. transition metal dichalcogenides(TMDs), group IVA metal chalcogenides and noble metals. For each group of materials, we begin with introducing the various existing crystal phases and their structure-related properties, followed by a detailed discussion on factors that influence these crystal structures and thus the possible strategies for phase control. Finally, after summarizing the whole paper, we present the challenges and opportunities in this research direction.
文摘We use laser-scanning nonlinear imaging microscopy in atomically thin transition metal dichalcogenides(TMDs)to reveal information on the crystalline orientation distribution,within the 2D lattice.In particular,we perform polarization-resolved second-harmonic generation(PSHG)imaging in a stationary,raster-scanned chemical vapor deposition(CVD)-grown WS2 flake,in order to obtain with high precision a spatially resolved map of the orientation of its main crystallographic axis(armchair orientation).By fitting the experimental PSHG images of sub-micron resolution into a generalized nonlinear model,we are able to determine the armchair orientation for every pixel of the image of the 2D material,with further improved resolution.This pixel-wise mapping of the armchair orientation of 2D WS2 allows us to distinguish between different domains,reveal fine structure,and estimate the crystal orientation variability,which can be used as a unique crystal quality marker over large areas.The necessity and superiority of a polarization-resolved analysis over intensity-only measurements is experimentally demonstrated,while the advantages of PSHG over other techniques are analysed and discussed.
基金funded by the National Natural Science Foundation of China (No. 21603109)the Henan Joint Fund of the National Natural Science Foundation of China (No. U1404216)+2 种基金the Special Fund of Tianshui Normal University, China (No. CXJ2020-08)the Scientific Research Program Funded by Shaanxi Provincial Education Department (No. 20JK0676)partially supported by the postgraduate research opportunities program of HZWTECH (HZWTECH-PROP).
文摘Ammonia borane(NH_(3)BH_(3),AB)has been considered to be a promising chemical hydrogen storage material.Based on density functional theory,a series of transition metal atoms supported P_(3)C(P_(3)C_O)sheet is systematically investigated to screen out the most promising catalyst for dehydrogenation of AB.The results indicate that the Os/P_(3)C and Os/P_(3)C_O could be an efficient single atom catalyst(SACs)and the stepwise reaction pathway with free energy barrier of 2.07 and 1.54 e V respectively.Remarkably,the rate constant further quantitatively confirmed the real situation of the first step of dehydrogenation of AB on the Os/P_(3)C and Os/P_(3)C_O substrates.We found that k_(f1)at 400 K is equivalent to k_(f2)at 800 K,which greatly improves the temperature of the first step of AB dehydrogenation on P_(3)C_O.We hope this work can provide a promising method for the design of catalysts for AB dehydrogenation reactions on the surface of two-dimensional materials(2D).
基金the National Natural Science Foundation of China(Nos.31900748,61905266,61975224,62004207,amd 62005303)Fund of Shanghai Natural Science Foundation(Nos.19YF1454600,18ZR1445800).
文摘Atomically thin two-dimensional(2D)materials exhibit enormous potential in photodetectors because of novel and extraordinary properties,such as passivated surfaces,tunable bandgaps,and high mobility.High-performance photodetectors based on 2D materials have been fabricated for broadband,position,polarization-sensitive detection,and large-area array imaging.However,the current performance of 2D material photodetectors is not outstanding enough,including response speed,detectivity,and so forth.The way to further promote the development of 2D material photodetectors and their corresponding practical applications is still a tremendous challenge.In this article,these issues of 2D material photodetectors are analyzed and expected to be solved by combining micro-nano characterization technologies.The inherent physical properties of 2D materials and photodetectors can be accurately characterized by Raman spectroscopy,transmission electron microscopy(TEM),and scattering scanning near-field optical microscope(s-SNOM).In particular,the precise probe of lattice defects,doping concentration,and near-field light absorption characteristics can promote the researches of low-noise and high-responsivity photodetectors.Scanning photocurrent microscope(SPCM)can show the overall spatial distribution of photocurrent and analyze the mechanism of photocurrent.Photoluminescence(PL)spectroscopy and Kelvin probe force microscope(KPFM)can characterize the material bandgap,work function distribution and interlayer coupling characteristics,making it possible to design high-performance photodetectors through energy band engineering.These advanced characterization techniques cover the entire process from material growth,to device preparation,and to performance analysis,and systematically reveal the development status of 2D material photodetectors.Finally,the prospects and challenges are discussed to promote the application of 2D material photodetectors.
基金financially supported by the Ministry of Science and Technology of China (2016YFB0401100 and 2017YFA0204503)the National Natural Science Foundation of China (51633006, 51725304, 51733004 and 51703159)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB12030300)
文摘Two-dimensional single-crystalline p-n junctions of organic semiconductors(pn-2 DCOSs) show great potential in organic logic circuits due to their single crystal nature and excellent ambipolar charge transport. However,there are only few reports on pn-2 DCOSs because it is difficult to obtain such highly ordered structure in p-n junction.Herein, a novel and effective solution processing method of secondary transfer technology based on the facile drop casting is used to fabricate devices of pn-2 DCOSs based on C8-BTBT(p-type) and TFT-CN(n-type) successfully. The high-performance ambipolar field transistors based on such ultrathin pn-2 DCOSs with several molecular layers thickness show wellbalanced ambipolar charge transport behaviors with hole mobility as high as 0.43 cm^2 V^-1 s^-1 and electron mobility up to 0.11 cm^2 V^-1 s(^-1), respectively. This work is essential for studying the intrinsic properties of organic p-n junctions and achieving high performance in organic complementary circuits.
基金This work was supported by Guangdong Major Project of Basic and Applied Basic Research(2021B030103000)the National Natural Science Foundation of China(12322406,52102043,52025023,51991342,52021006 and 61905215)+5 种基金the Key R&D Program of Guangdong Province(2020B010189001,2019B010931001,2018B010109009 and 2018B030327001)the Pearl River Talent Recruitment Program of Guangdong Province(2019ZT08C321)the Key Project of Science and Technology of Guangzhou(202201010383)the Natural Science Foundation o f Guangdong Provinces(2023A1515012743)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB3300000)the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘Among the various two-dimensional(2D)materials,more than 99%of them are noncentrosymmetric.However,since the commonly used substrates are generally centrosymmetric,antiparallel islands are usually inevitable in the growth of noncentrosymmetric 2D materials because of the energetic equivalency of these two kinds of antiparallel islands on centrosymmetric substrates.Therefore,achieving the growth of noncentrosymmetric 2D single crystals has long been a great challenge compared with the centrosymmetric ones like graphene.In this review,we presented the remarkable efforts and progress in the past decade,through precise chemical processes.We first discussed the great challenge and possible strategies in the growth of noncentrosymmetric 2D single crystals.Then,we focused on the advancements made in producing representative noncentrosymmetric 2D single crystals,including hexagonal boron nitride(hBN),transition metal dichalcogenides(TMDs),and other noncentrosymmetric 2D materials.At last,we summarized and looked forward to future research on the growth of layer-,stacking-,and twist-controlled noncentrosymmetric 2D single crystals and their heterostructures.
基金This work was supported by the National Natural Science Foundation of China(Nos.62322406,62174051,and 62122084)the National Key Research and Development Program of the Ministry of Science and Technology(Nos.2024YFA1208401 and 2022YFB4400100)+2 种基金the Natural Science Foundation of Hunan Province(No.2024JJ6115)the Shenzhen Basic Research Project(No.JCYJ20210324142012035)Natural Science Foundation of Chongqing,China(No.cstc2021jcyj-msxmX0126)。
文摘Giant tunneling magnetoresistance(TMR)has always been a pursuit in the research of magnetic tunnel junctions(MTJ).Two-dimensional(2D)magnetic materials have been used to construct lateral MTJ with high TMR.Here we investigated the crystal structure and magnetic property of CrSI monolayer,and found that it is a ferromagnetic semiconductor with a Curie temperature of about 180 K.The CrSI monolayer with Li adsorption(Li-CrSI)show ferromagnetic half-metallic with a high Curie temperature of 300 K.Further we designed a lateral Li CrSI/CrSI/Li-CrSI monolayer MTJ.The TMR of the MTJs along b transport direction is 3 orders of magnitude times larger than that of the a transport direction,which should result from the different spin filtering ability along the two directions.The TMR of b transport direction in the MTJ is 7.67×10^(14),which is significantly higher than that of any reported lateral MTJs based on 2D materials.Our results provide a promising avenue for designing lateral MTJs with giant TMR and high Curie temperature.
文摘It is suggested that there is a kind of probability wave of the atomic configuration p(R)in crystals that can be deduced from the eigenequation of the ionic interaction Hamiltonian,and it has definite physical meaning. By use of the probability wave of the atomic con-figuration, the occupation probabilities of different kinds of atoms at lattice sites in multi-component solutions can be studied, and the crystal structures of multi-component solutionscan be predicted.
基金financial support from the National Natural Science Foundation of China(Nos.22171094,21925104,92261204,and 22431005)Hubei Provincial Science and Technology Innovation Team Project[2022]The National Key R&D Program of China(No.2022YFB3807700)。
文摘Atomically precise coordination nanoclusters(NCs)constitute a pivotal and rapidly advancing domain in the realms of materials science and chemistry owing to their distinctive crystal structures and exceptional attributes encompassing molecular magnetism[1],photoluminescence[2],and catalysis[3].Organic ligands play a crucial role in effectively shielding these NCs,serving two primary functions:firstly,vital in preventing NC aggregation,particularly for the formation of robust single-crystal structures;secondly,acting as either bridging or peripheral structural components of NCs[4].This characterization of organic-inorganic hybridization offers unique advantages for unraveling the intricate relationships between structure and properties[5].
