Two-dimensional(2D)metal oxides(2DMOs),such as MoO_(2),have made impressive strides in recent years,and their applicability in a number of fields such as electronic devices,optoelectronic devices and lasers has been d...Two-dimensional(2D)metal oxides(2DMOs),such as MoO_(2),have made impressive strides in recent years,and their applicability in a number of fields such as electronic devices,optoelectronic devices and lasers has been demonstrated.However,2DMOs present challenges in their synthesis using conventional methods due to their non-van der Waals nature.We report that KCl acts as a flux to prepare large-area 2DMOs with sub-millimeter scale.We systematically investigate the effects of temperature,homogeneous time and cooling rate on the products in the flux method,demonstrating that in this reaction a saturated homogenous solution is obtained upon the melting of the salt and precursor.Afterward,the cooling rate was adjusted to regulate the thickness of the target crystals,leading to the precipitation of 2D non-layered material from the supersaturated solution;by applying this method,the highly crystalline non-layered 2D MoO_(2)flakes with so far the largest lateral size of up to sub-millimeter scale(~464μm)were yielded.Electrical studies have revealed that the 2D MoO_(2)features metallic properties,with an excellent sheet resistance as low as 99Ω·square^(-1 )at room temperature,and exhibits a property of charge density wave in the measurement of resistivity as a function of temperature.展开更多
Non-layered two-dimensional(2D)materials have sparked much interest recently due to their atomic thickness,large surface area,thickness-and facet-dependent properties.Currently,these materials are mainly grown from we...Non-layered two-dimensional(2D)materials have sparked much interest recently due to their atomic thickness,large surface area,thickness-and facet-dependent properties.Currently,these materials are mainly grown from wet-chemistry methods but suffer from small size,low quality,and multi-facets,which is a major challenge hindering their facet-dependent property studies and applications.Here,we report the facet-engineered growth(FEG)of non-layered 2D manganese chalcogenides(MnX,X=S,Se,Te)based on the chemical vapor deposition method.The as-grown samples exhibit large-area surfaces of single facet,high-crystallinity,and ordered domain orientation.As a proof-of-concept,we show the facet-dependent electrocatalytic property of non-layered 2D MnSe,proving they are ideal candidates for fundamental research.Furthermore,we elucidate the underlying mechanism of FEG during the vapor growth process by the interfacial energy derived nucleation models.The method developed in this work provides new opportunities for regulating and designing the structure of 2D materials.展开更多
Non-layered two-dimensional(2 D)carbon complexes manifest great potential in energy-related applications owing to their exotic electronic structures,large electrochemically active surface,and intriguing synergistic ef...Non-layered two-dimensional(2 D)carbon complexes manifest great potential in energy-related applications owing to their exotic electronic structures,large electrochemically active surface,and intriguing synergistic effects.However,reliable method for mass production and thickness manipulation of 2 D carbon complexes remains great challenges.Here,inspired by blowing chewing gum into bubbles,a“tailored gel expanding"strategy is proposed for high-yield synthesis of non-layered 2 D carbon complexes with tailored thickness from~12 nm to~1 lm,by controllable pyrolysis of metal-polymeric gel with adequate crosslinking degree.The key feature for thickness manipulation is introducing NH4 NO3 in sol-gel process,which tailors the expansion behavior of gel precursor during subsequent pyrolysis.Various of 2 D sheets with intimately coupled N,O-doped carbon(NOC)and Ni Co-based(Ni Co,(Ni Co)S_(2),(Ni Co)Se_(2),Ni Co_(2)O_(4),(Ni Co)(PO_(3))_(2))nanocrystals are obtained on a large scale and without any impurities.Moreover,these 2 D products are branched with in-situ grown CNTs on the surface,accelerating electrons transfer and preventing the nanosheets from stacking.As a demonstration,the 2 D(Ni Co)S_(2)/NOC with optimized thickness manifests excellent lithium storage properties in both half and full cells.This method paves a new path for massive and controlled production of non-layered 2 D materials with tailored thickness and robust structure stability for energy-related applications.展开更多
With the development of Moore's law, the future trend of devices will inevitably be shrinking and integration to further achieve size reduction. The emergence of new two-dimensional non-layered materials(2DNLMs) n...With the development of Moore's law, the future trend of devices will inevitably be shrinking and integration to further achieve size reduction. The emergence of new two-dimensional non-layered materials(2DNLMs) not only enriches the 2D material family to meet future development, but also stimulates the global enthusiasm for basic research and application technologies in the 2D field. Van der Waals(vd W) heterostructures, in which two-dimensional layered materials(2DLMs)are physically stacked layer by layer, can also occur between 2DLMs and 2DNLMs hybrid heterostructures, providing an alternative platform for nanoelectronics and optoelectronic applications. Here, we outline the recent developments of2DLMs/2DNLMs hybrid heterostructures, with particular emphasis on major advances in synthetic methods and applications. And the categories and crystal structures of 2DLMs and 2DNLMs are also shown. We highlight some promising applications of the heterostructures in electronics, optoelectronics, and catalysis. Finally, we provide conclusions and future prospects in the 2D materials field.展开更多
Two-dimensional(2D)transition metal chalcogenides(TMCs)are promising for nanoelectronics and energy applications.Among them,the emerging non-layered TMCs are unique due to their unsaturated dangling bonds on the surfa...Two-dimensional(2D)transition metal chalcogenides(TMCs)are promising for nanoelectronics and energy applications.Among them,the emerging non-layered TMCs are unique due to their unsaturated dangling bonds on the surface and strong intralayer and interlayer bonding.However,the synthesis of non-layered 2D TMCs is challenging and this has made it difficult to study their structures and properties at thin thickness limit.Here,we develop a universal dual-metal precursors method to grow non-layered TMCs in which a mixture of a metal and its chloride serves as the metal source.Taking hexagonal Fe_(1-x)S as an example,the thickness of the Fe_(1-x)S flakes is down to 3 nm with a lateral size of over 100 μm.Importantly,we find ordered cation Fe vacancies in Fe_(1-x)S,which is distinct from layered TMCs like MoS_(2) where anion vacancies are commonly observed.Low-temperature transport measurements and theoretical calculations show that 2D Fe_(1-x)S is a stable semiconductor with a narrow bandgap of60 meV.In addition to Fe_(1-x)S,the method is universal in growing various non-layered 2D TMCs containing ordered cation vacancies,including Fe_(1-x)Se,Co_(1-x)S,Cr_(1-x)S,and V_(1-x)S.This work paves the way to grow and exploit properties of non-layered materials at 2D thickness limit.展开更多
Two-dimensional(2D)non-layered materials,along with their unique surface properties,offer intriguing prospects for sensing applications.Introducing mechanical degrees of freedom is expected to enrich the sensing perfo...Two-dimensional(2D)non-layered materials,along with their unique surface properties,offer intriguing prospects for sensing applications.Introducing mechanical degrees of freedom is expected to enrich the sensing performances of 2D non-layered devices,such as high frequency,high tunability,and large dynamic range,which could lead to new types of high performance nanosensors.Here,we demonstrate 2D non-layered nanomechanical resonant sensors based onβ-In_(2)S_(3),where the devices exhibit robust nanomechanical vibrations up to the very high frequency(VHF)band.We show that such device can operate as pressure sensor with broad range(from 103 Torr to atmospheric pressure),high linearity(with a nonlinearity factor as low as 0.0071),and fast response(with an intrinsic response time less than 1μs).We further unveil the frequency scaling law in theseβ-In_(2)S_(3) nanomechanical sensors and successfully extract both the Young's modulus and pretension for the crystal.Our work paves the way towards future wafer-scale design and integrated sensors based on 2D non-layered materials.展开更多
Two-dimensional(2D)semiconductors with intrinsic ferromagnetism are highly desirable for potential applications in nextgeneration spintronic and optoelectronic devices.However,controllable synthesis of intrinsic 2D ma...Two-dimensional(2D)semiconductors with intrinsic ferromagnetism are highly desirable for potential applications in nextgeneration spintronic and optoelectronic devices.However,controllable synthesis of intrinsic 2D magnetic semiconductor on a substrate is still a challenging task.Herein,large-area 2D non-layered rock salt(α-phase)MnSe nanosheets were grown on mica substrates,with the thickness changing from 54.2 to 0.9 nm(one unit cell),by chemical vapour deposition.The X-ray diffraction,Raman spectroscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy measurements confirmed that the resulting 2Dα-MnSe nanosheets were obtained as high-quality single crystals.The magnetic hysteresis loops and synchrotron X-ray measurements directly indicated the anomalous magnetic properties inα-MnSe nanosheets.Comprehensive analysis of the reasons for magnetic property revealed that the low-temperature phase transition,small number of stacking differences in crystals,and surface weak oxidation in(111)-orientedα-MnSe were the main mechanisms.Furthermore,α-MnSe nanosheets exhibited broadband photoresponse from 457 to 671 nm with an outstanding detectivity and responsivity behaviours.This study presents the detailed growth process of ultrathin 2D magnetic semiconductorα-MnSe,and its outstanding magnetic properties and broadband photodetection,which provide an excellent platform for magneto-optical and magneto-optoelectronic research.展开更多
Non-layered two-dimensional(2D) lead-free all-inorganic perovskites nanoplates have recently attracted considerable attention in photodetectors;however, the indepth investigation of thickness on photodetection perform...Non-layered two-dimensional(2D) lead-free all-inorganic perovskites nanoplates have recently attracted considerable attention in photodetectors;however, the indepth investigation of thickness on photodetection performance is still lacking. In this work, by constructing the famous metal-semiconductor-metal photodetectors, the photodetection behaviors of thickness-controlled CsSnBr;nanoplates are investigated systematically. Ni electrodes are adopted for ensuring the good ohmic contact behaviors of as-fabricated photodetectors. With the increase in thickness, the photodetection performances improve accordingly, such as photocurrent increases from 0.22 to 19.40 nA, responsivity increases from 72.9 to 4893.7 mA·W^(-1), rise/decay time decreases from 11/35 to 3/10 ms, respectively. Notability, the dark current also increases with the increase in thickness, making the further investigation on the reduction in dark current meaningful.All of the as-fabricated photodetectors are stable, suggesting the careful thickness selection in next-generation high-performance lead-free all-inorganic perovskites photodetectors.展开更多
Two-dimensional(2D)magnet/superconductor heterostructures can promote the design of artificial materials for exploring 2D physics and device applications by exotic proximity effects.However,plagued by the low Curie te...Two-dimensional(2D)magnet/superconductor heterostructures can promote the design of artificial materials for exploring 2D physics and device applications by exotic proximity effects.However,plagued by the low Curie temperature and instability in air,it is hard to realize practical applications for the reported layered magnetic materials at present.In this paper,we developed a space-confined chemical vapor deposition method to synthesize ultrathin air-stable ε-Fe_(2)O_(3) nanosheets with Curie temperature above 350 K.The ε-Fe_(2)O_(3)/NbSe_(2) heterojunction was constructed to study the magnetic proximity effect on the superconductivity of the NbSe_(2) multilayer.The electrical transport results show that the subtle proximity effect can modulate the interfacial spin–orbit interaction while undegrading the superconducting critical parameters.Our work paves the way to construct 2D heterojunctions with ultrathin nonlayered materials and layered van der Waals(vdW)materials for exploring new physical phenomena.展开更多
Considerable progress has been made in synthesizing two-dimensional(2D)materials by exfoliating layered solids.However;for tremendous non-layered inorganic materials;especially magnet solids;usually with closely packe...Considerable progress has been made in synthesizing two-dimensional(2D)materials by exfoliating layered solids.However;for tremendous non-layered inorganic materials;especially magnet solids;usually with closely packed bulk phases by strong chemical bonds;it is challenging to obtain their high-quality 2D sheets.Herein;we highlighted a new structure of free-standing ferromagnetic nanosheets featuring(111)facets.For magnet;Fe_(3)O_(4);its inversed spinel crystalline has limited abilities to exfoliate into 2D forms and rarely exists as free-standing nanosheets owing to aggregation induced by magnetic force.We realized a breakthrough in achieving free-standing ferromagnetic nanosheets with dramatically surpassing size limitations via topotactic conversion from layered counterparts.Our Fe_(3)O_(4) nanosheets exhibited a maximum width of 60μm while onl y~4 nm thick;prominently exposing(111)facets.2D Fe_(3)O_(4) behaved anisotropic magnetism;which displayed a 4.6 emu g^(-1) moment(H=500 Oe)in the(111)plane but 2.1 emu g^(-1)out of the(111)plane;indicating a(111)in-plane easy axis.We anticipated our topotactic conversion strategy would inspire the creation of 2D non-layered materials and enrich the 2D materials family.展开更多
Two-dimensional(2D) materials with atomic thickness are promising candidates for the applications in future semiconductor devices, owing to their fascinating physical properties and superlative optoelectronic performa...Two-dimensional(2D) materials with atomic thickness are promising candidates for the applications in future semiconductor devices, owing to their fascinating physical properties and superlative optoelectronic performance. Chemical vapor deposition(CVD) is considered to be an efficient method for large-scale preparation of 2D materials toward practical applications.However, the high melting points of metal precursors and the thermodynamics instabilities of metastable phases limit the direct CVD synthesis of plenty of 2D materials. The salt has recently been introduced into the CVD process, which proved to be effective to address these issues. In this review, we highlighted the latest progress in the salt-assisted CVD growth of 2D materials, including layered and non-layered crystals. Firstly, strategies of adding salts are summarized. Then, the salt-assisted growth of various layered materials is presented, emphasizing on the transition metal chalcogenides of stable and metastable phases. Furthermore, strategies to grow ultrathin non-layered materials are discussed. We provide viewpoints into the techniques of using salt, the effects of salt, and the growth mechanisms of 2D crystals. Finally, we offer the challenges to be overcome and further research directions of this emerging salt-assisted CVD technique.展开更多
Two-dimensional(2D)materials have attracted a great deal of research interest because of their unique electrical,magnetic,optical,mechanical,and catalytic properties for various applications.To date,however,it is stil...Two-dimensional(2D)materials have attracted a great deal of research interest because of their unique electrical,magnetic,optical,mechanical,and catalytic properties for various applications.To date,however,it is still difficult to fabricate most functional oxides as 2D materials unless they have a layered structure.Herein,we report a one-step universal strategy for preparing versatile non-layered oxide nanosheets by directly annealing the mixture of metal nitrate and dimethyl imidazole(2-MI).The 2-MI plays the key role for 2D oxides since 2-MI owns a very low molten point and sublimation temperature,in which its molten liquid can coordinate with metal ions,forming a metal-organic framework,and easily puffing by its gas molecules.A total of 17 materials were prepared by this strategy,including non-layered metal oxide nanosheets as well as metal/metal oxide loaded nitrogen-doped carbon nanosheets.The as-prepared cobalt particle-loaded nitrogen-doped carbon nanosheets(Co@N/C)exhibit remarkable bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalytic activity and durability.Besides,the Zn-air battery utilizing a Co@N/C catalyst exhibits high power density of 174.3 mW·cm^(-2).This facile strategy opens up a new way for large-scale synthesis of 2D oxides that holds great potential to push 2D oxides for practical applications.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2023YFB3608703 and 2023YFB3608700)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(Nos.2021ZZ122 and 2020ZZ110)Fujian provincial projects(Nos.2021HZ0114 and 2021J01583).
文摘Two-dimensional(2D)metal oxides(2DMOs),such as MoO_(2),have made impressive strides in recent years,and their applicability in a number of fields such as electronic devices,optoelectronic devices and lasers has been demonstrated.However,2DMOs present challenges in their synthesis using conventional methods due to their non-van der Waals nature.We report that KCl acts as a flux to prepare large-area 2DMOs with sub-millimeter scale.We systematically investigate the effects of temperature,homogeneous time and cooling rate on the products in the flux method,demonstrating that in this reaction a saturated homogenous solution is obtained upon the melting of the salt and precursor.Afterward,the cooling rate was adjusted to regulate the thickness of the target crystals,leading to the precipitation of 2D non-layered material from the supersaturated solution;by applying this method,the highly crystalline non-layered 2D MoO_(2)flakes with so far the largest lateral size of up to sub-millimeter scale(~464μm)were yielded.Electrical studies have revealed that the 2D MoO_(2)features metallic properties,with an excellent sheet resistance as low as 99Ω·square^(-1 )at room temperature,and exhibits a property of charge density wave in the measurement of resistivity as a function of temperature.
基金This work was supported by the National Science Fund for Distinguished Young Scholars(52125309)the National Natural Science Foundation of China(51991343,51920105002,and 52102179)+4 种基金Guangdong Basic and Applied Basic Research Foundation(2023A1515011752)Guangdong Innovative and Entrepreneurial Research Team Program(2017ZT07C341)Shenzhen Basic Research Project(JCYJ20200109144616617,JCYJ20220818101014029)Shuimu Tsinghua Scholar Program(2022SM092)China Postdoctoral Science Foundation(2021M691715)。
文摘Non-layered two-dimensional(2D)materials have sparked much interest recently due to their atomic thickness,large surface area,thickness-and facet-dependent properties.Currently,these materials are mainly grown from wet-chemistry methods but suffer from small size,low quality,and multi-facets,which is a major challenge hindering their facet-dependent property studies and applications.Here,we report the facet-engineered growth(FEG)of non-layered 2D manganese chalcogenides(MnX,X=S,Se,Te)based on the chemical vapor deposition method.The as-grown samples exhibit large-area surfaces of single facet,high-crystallinity,and ordered domain orientation.As a proof-of-concept,we show the facet-dependent electrocatalytic property of non-layered 2D MnSe,proving they are ideal candidates for fundamental research.Furthermore,we elucidate the underlying mechanism of FEG during the vapor growth process by the interfacial energy derived nucleation models.The method developed in this work provides new opportunities for regulating and designing the structure of 2D materials.
基金supported by the National Natural Science Foundation of China(Grant Nos.51902102,51672059,21805171)the Taishan Scholars Talent Plan(No.ts201511080)+2 种基金the Natural Science Foundation of Hunan Province(Grant No.2020JJ5042)the Natural Science Foundation of Shandong Province(Grant No.ZR2018BB038)the Qiqihar Science and Technology Project(GYGG-201908)。
文摘Non-layered two-dimensional(2 D)carbon complexes manifest great potential in energy-related applications owing to their exotic electronic structures,large electrochemically active surface,and intriguing synergistic effects.However,reliable method for mass production and thickness manipulation of 2 D carbon complexes remains great challenges.Here,inspired by blowing chewing gum into bubbles,a“tailored gel expanding"strategy is proposed for high-yield synthesis of non-layered 2 D carbon complexes with tailored thickness from~12 nm to~1 lm,by controllable pyrolysis of metal-polymeric gel with adequate crosslinking degree.The key feature for thickness manipulation is introducing NH4 NO3 in sol-gel process,which tailors the expansion behavior of gel precursor during subsequent pyrolysis.Various of 2 D sheets with intimately coupled N,O-doped carbon(NOC)and Ni Co-based(Ni Co,(Ni Co)S_(2),(Ni Co)Se_(2),Ni Co_(2)O_(4),(Ni Co)(PO_(3))_(2))nanocrystals are obtained on a large scale and without any impurities.Moreover,these 2 D products are branched with in-situ grown CNTs on the surface,accelerating electrons transfer and preventing the nanosheets from stacking.As a demonstration,the 2 D(Ni Co)S_(2)/NOC with optimized thickness manifests excellent lithium storage properties in both half and full cells.This method paves a new path for massive and controlled production of non-layered 2 D materials with tailored thickness and robust structure stability for energy-related applications.
基金Project supported by the National Natural Science Fundation of China (Grant Nos. 61731019, 60908012, 61575008, and 61775007)the Beijing Natural Science Foundation (Grant Nos. 4182015 and 4202010)。
文摘With the development of Moore's law, the future trend of devices will inevitably be shrinking and integration to further achieve size reduction. The emergence of new two-dimensional non-layered materials(2DNLMs) not only enriches the 2D material family to meet future development, but also stimulates the global enthusiasm for basic research and application technologies in the 2D field. Van der Waals(vd W) heterostructures, in which two-dimensional layered materials(2DLMs)are physically stacked layer by layer, can also occur between 2DLMs and 2DNLMs hybrid heterostructures, providing an alternative platform for nanoelectronics and optoelectronic applications. Here, we outline the recent developments of2DLMs/2DNLMs hybrid heterostructures, with particular emphasis on major advances in synthetic methods and applications. And the categories and crystal structures of 2DLMs and 2DNLMs are also shown. We highlight some promising applications of the heterostructures in electronics, optoelectronics, and catalysis. Finally, we provide conclusions and future prospects in the 2D materials field.
基金supported by the National Science Fund for Distinguished Young Scholars(52125309)the National Natural Science Foundation of China(51991343,51920105002,51991340,52188101,and 11974156)+3 种基金Guangdong Innovative and Entrepreneurial Research Team Program(2017ZT07C341 and 2019ZT08C044)the Bureau of Industry and Information Technology of Shenzhen for the “2017 Graphene Manufacturing Innovation Center Project”(201901171523)Shenzhen Basic Research Project(JCYJ20200109144616617 and JCYJ20190809180605522)Shenzhen Science and Technology Program(KQTD20190929173815000 and 20200925161102001)。
文摘Two-dimensional(2D)transition metal chalcogenides(TMCs)are promising for nanoelectronics and energy applications.Among them,the emerging non-layered TMCs are unique due to their unsaturated dangling bonds on the surface and strong intralayer and interlayer bonding.However,the synthesis of non-layered 2D TMCs is challenging and this has made it difficult to study their structures and properties at thin thickness limit.Here,we develop a universal dual-metal precursors method to grow non-layered TMCs in which a mixture of a metal and its chloride serves as the metal source.Taking hexagonal Fe_(1-x)S as an example,the thickness of the Fe_(1-x)S flakes is down to 3 nm with a lateral size of over 100 μm.Importantly,we find ordered cation Fe vacancies in Fe_(1-x)S,which is distinct from layered TMCs like MoS_(2) where anion vacancies are commonly observed.Low-temperature transport measurements and theoretical calculations show that 2D Fe_(1-x)S is a stable semiconductor with a narrow bandgap of60 meV.In addition to Fe_(1-x)S,the method is universal in growing various non-layered 2D TMCs containing ordered cation vacancies,including Fe_(1-x)Se,Co_(1-x)S,Cr_(1-x)S,and V_(1-x)S.This work paves the way to grow and exploit properties of non-layered materials at 2D thickness limit.
基金National Natural Science Foundation of China,Grant/Award Numbers:T2325007,62250073,U21A20459,62004026,61774029,62104029,12104086,U23A20570,51902346Sichuan Science and Technology Program,Grant/Award Numbers:24NSFSC5852,24NSFSC5853Science and Technology Innovation Program of Hunan Province,Grant/Award Number:2021RC3021。
文摘Two-dimensional(2D)non-layered materials,along with their unique surface properties,offer intriguing prospects for sensing applications.Introducing mechanical degrees of freedom is expected to enrich the sensing performances of 2D non-layered devices,such as high frequency,high tunability,and large dynamic range,which could lead to new types of high performance nanosensors.Here,we demonstrate 2D non-layered nanomechanical resonant sensors based onβ-In_(2)S_(3),where the devices exhibit robust nanomechanical vibrations up to the very high frequency(VHF)band.We show that such device can operate as pressure sensor with broad range(from 103 Torr to atmospheric pressure),high linearity(with a nonlinearity factor as low as 0.0071),and fast response(with an intrinsic response time less than 1μs).We further unveil the frequency scaling law in theseβ-In_(2)S_(3) nanomechanical sensors and successfully extract both the Young's modulus and pretension for the crystal.Our work paves the way towards future wafer-scale design and integrated sensors based on 2D non-layered materials.
基金supported by the National Natural Science Foundation of China(Nos.12174237,52002232,and 12304148)Fundamental Research Program of Shanxi Province(202303021221152).
文摘Two-dimensional(2D)semiconductors with intrinsic ferromagnetism are highly desirable for potential applications in nextgeneration spintronic and optoelectronic devices.However,controllable synthesis of intrinsic 2D magnetic semiconductor on a substrate is still a challenging task.Herein,large-area 2D non-layered rock salt(α-phase)MnSe nanosheets were grown on mica substrates,with the thickness changing from 54.2 to 0.9 nm(one unit cell),by chemical vapour deposition.The X-ray diffraction,Raman spectroscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy measurements confirmed that the resulting 2Dα-MnSe nanosheets were obtained as high-quality single crystals.The magnetic hysteresis loops and synchrotron X-ray measurements directly indicated the anomalous magnetic properties inα-MnSe nanosheets.Comprehensive analysis of the reasons for magnetic property revealed that the low-temperature phase transition,small number of stacking differences in crystals,and surface weak oxidation in(111)-orientedα-MnSe were the main mechanisms.Furthermore,α-MnSe nanosheets exhibited broadband photoresponse from 457 to 671 nm with an outstanding detectivity and responsivity behaviours.This study presents the detailed growth process of ultrathin 2D magnetic semiconductorα-MnSe,and its outstanding magnetic properties and broadband photodetection,which provide an excellent platform for magneto-optical and magneto-optoelectronic research.
基金the National Key R&D Program of China(No.2017YFA0305500)the National Natural Science Foundation of China(Nos.61904096 and 62104133)+3 种基金Taishan Scholars Program of Shandong Province(No.tsqn201812006)Shandong University Youth Innovation Supporting Program(No.2019KJN020)Shandong University Multidisciplinary Research and Innovation Team of Young Scholars(No.2020QNQT015)‘‘Outstanding Youth Scholar and Qilu Young Scholar’’programs of Shandong University。
文摘Non-layered two-dimensional(2D) lead-free all-inorganic perovskites nanoplates have recently attracted considerable attention in photodetectors;however, the indepth investigation of thickness on photodetection performance is still lacking. In this work, by constructing the famous metal-semiconductor-metal photodetectors, the photodetection behaviors of thickness-controlled CsSnBr;nanoplates are investigated systematically. Ni electrodes are adopted for ensuring the good ohmic contact behaviors of as-fabricated photodetectors. With the increase in thickness, the photodetection performances improve accordingly, such as photocurrent increases from 0.22 to 19.40 nA, responsivity increases from 72.9 to 4893.7 mA·W^(-1), rise/decay time decreases from 11/35 to 3/10 ms, respectively. Notability, the dark current also increases with the increase in thickness, making the further investigation on the reduction in dark current meaningful.All of the as-fabricated photodetectors are stable, suggesting the careful thickness selection in next-generation high-performance lead-free all-inorganic perovskites photodetectors.
基金The work is supported by the National Key Research and Development Program of China(Grant No.2022YFA1204104)the National Natural Science Foundation of China(Grant No.61888102)the Chinese Academy of Sciences(Grant Nos.ZDBS-SSW-WHC001 and XDB33030100).
文摘Two-dimensional(2D)magnet/superconductor heterostructures can promote the design of artificial materials for exploring 2D physics and device applications by exotic proximity effects.However,plagued by the low Curie temperature and instability in air,it is hard to realize practical applications for the reported layered magnetic materials at present.In this paper,we developed a space-confined chemical vapor deposition method to synthesize ultrathin air-stable ε-Fe_(2)O_(3) nanosheets with Curie temperature above 350 K.The ε-Fe_(2)O_(3)/NbSe_(2) heterojunction was constructed to study the magnetic proximity effect on the superconductivity of the NbSe_(2) multilayer.The electrical transport results show that the subtle proximity effect can modulate the interfacial spin–orbit interaction while undegrading the superconducting critical parameters.Our work paves the way to construct 2D heterojunctions with ultrathin nonlayered materials and layered van der Waals(vdW)materials for exploring new physical phenomena.
基金supported by the CAS Project for Young Scientists in Basic Research(YSBR-070)the National Natural Science Foundation of China(21925110,22321001,U2032161,12147105,22201273,22205226)+3 种基金the National Key Research and Development Program of China(2022YFA1203601,2022YFA1203601,2022YFA1203602)the USTC Research Funds of the Double First-Class Initiative(YD2060002004,WK2060000047)the University Synergy Innovation Program of Anhui Province(GXXT-2022-006)the support from the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology.
文摘Considerable progress has been made in synthesizing two-dimensional(2D)materials by exfoliating layered solids.However;for tremendous non-layered inorganic materials;especially magnet solids;usually with closely packed bulk phases by strong chemical bonds;it is challenging to obtain their high-quality 2D sheets.Herein;we highlighted a new structure of free-standing ferromagnetic nanosheets featuring(111)facets.For magnet;Fe_(3)O_(4);its inversed spinel crystalline has limited abilities to exfoliate into 2D forms and rarely exists as free-standing nanosheets owing to aggregation induced by magnetic force.We realized a breakthrough in achieving free-standing ferromagnetic nanosheets with dramatically surpassing size limitations via topotactic conversion from layered counterparts.Our Fe_(3)O_(4) nanosheets exhibited a maximum width of 60μm while onl y~4 nm thick;prominently exposing(111)facets.2D Fe_(3)O_(4) behaved anisotropic magnetism;which displayed a 4.6 emu g^(-1) moment(H=500 Oe)in the(111)plane but 2.1 emu g^(-1)out of the(111)plane;indicating a(111)in-plane easy axis.We anticipated our topotactic conversion strategy would inspire the creation of 2D non-layered materials and enrich the 2D materials family.
基金supported by the National Natural Science Foundation of China (21825103, 51727809)the Fundamental Research Funds for the Central University (2019kfy XMBZ018)the project funded by China Postdoctoral Science Foundation (2018M642832)
文摘Two-dimensional(2D) materials with atomic thickness are promising candidates for the applications in future semiconductor devices, owing to their fascinating physical properties and superlative optoelectronic performance. Chemical vapor deposition(CVD) is considered to be an efficient method for large-scale preparation of 2D materials toward practical applications.However, the high melting points of metal precursors and the thermodynamics instabilities of metastable phases limit the direct CVD synthesis of plenty of 2D materials. The salt has recently been introduced into the CVD process, which proved to be effective to address these issues. In this review, we highlighted the latest progress in the salt-assisted CVD growth of 2D materials, including layered and non-layered crystals. Firstly, strategies of adding salts are summarized. Then, the salt-assisted growth of various layered materials is presented, emphasizing on the transition metal chalcogenides of stable and metastable phases. Furthermore, strategies to grow ultrathin non-layered materials are discussed. We provide viewpoints into the techniques of using salt, the effects of salt, and the growth mechanisms of 2D crystals. Finally, we offer the challenges to be overcome and further research directions of this emerging salt-assisted CVD technique.
基金supported by the National Key Research and Development Program of China(No.2022YFA1203500)the National Natural Science Foundation of China(Nos.51972124 and 51902115)the Opening Project of Hubei Key Laboratory of Biomass Fibers and Eco-Dyeing&Finishing(No.223009025).
文摘Two-dimensional(2D)materials have attracted a great deal of research interest because of their unique electrical,magnetic,optical,mechanical,and catalytic properties for various applications.To date,however,it is still difficult to fabricate most functional oxides as 2D materials unless they have a layered structure.Herein,we report a one-step universal strategy for preparing versatile non-layered oxide nanosheets by directly annealing the mixture of metal nitrate and dimethyl imidazole(2-MI).The 2-MI plays the key role for 2D oxides since 2-MI owns a very low molten point and sublimation temperature,in which its molten liquid can coordinate with metal ions,forming a metal-organic framework,and easily puffing by its gas molecules.A total of 17 materials were prepared by this strategy,including non-layered metal oxide nanosheets as well as metal/metal oxide loaded nitrogen-doped carbon nanosheets.The as-prepared cobalt particle-loaded nitrogen-doped carbon nanosheets(Co@N/C)exhibit remarkable bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalytic activity and durability.Besides,the Zn-air battery utilizing a Co@N/C catalyst exhibits high power density of 174.3 mW·cm^(-2).This facile strategy opens up a new way for large-scale synthesis of 2D oxides that holds great potential to push 2D oxides for practical applications.
