Nonlayered two-dimensional(2D)materials have attracted increasing attention,due to novel physical properties,unique surface structure,and high compatibility with microfabrication technique.However,owing to the inheren...Nonlayered two-dimensional(2D)materials have attracted increasing attention,due to novel physical properties,unique surface structure,and high compatibility with microfabrication technique.However,owing to the inherent strong covalent bonds,the direct synthesis of 2D planar structure from nonlayered materials,especially for the realization of large-size ultrathin 2D nonlayered materials,is still a huge challenge.Here,a general atomic substitution conversion strategy is proposed to synthesize large-size,ultrathin nonlayered 2D materials.Taking nonlayered CdS as a typical example,large-size ultrathin nonlayered CdS single-crystalline flakes are successfully achieved via a facile low-temperature chemical sulfurization method,where pre-grown layered CdI2 flakes are employed as the precursor via a simple hot plate assisted vertical vapor deposition method.The size and thickness of CdS flakes can be controlled by the CdI2 precursor.The growth mechanism is ascribed to the chemical substitution reaction from I to S atoms between CdI2 and CdS,which has been evidenced by experiments and theoretical calculations.The atomic substitution conversion strategy demonstrates that the existing 2D layered materials can serve as the precursor for difficult-to-synthesize nonlayered 2D materials,providing a bridge between layered and nonlayered materials,meanwhile realizing the fabrication of large-size ultrathin nonlayered 2D materials.展开更多
Two-dimensional(2D)MoO_(2),a binary nonlayered material,has been extensively studied for potential applications in catalysis and electronics.However,the preparation of 2D MoO_(2) remains challenging.Herein,we report t...Two-dimensional(2D)MoO_(2),a binary nonlayered material,has been extensively studied for potential applications in catalysis and electronics.However,the preparation of 2D MoO_(2) remains challenging.Herein,we report the growth of 2D MoO_(2) flakes with rhombic morphology on the sapphire substrate via a chemical vapor deposition(CVD)method.Atomic force microscopy shows the CVDgrown MoO_(2) flakes with thin thickness.The CVD-obtained MoO_(2) with a stoichiometric ratio of 1:2 is verified using energy-dispersive X-ray spectroscopy.Scanning transmission electron microscopy(STEM)characterization reveals the high-quality,single-crystal nature of the CVDderived 2D MoO_(2) flakes.展开更多
The practical application of Lithium-Sulfur batteries largely depends on highly efficient utilization and conversion of sulfur under the realistic condition of high-sulfur content and low electrolyte/sulfur ratio.Rati...The practical application of Lithium-Sulfur batteries largely depends on highly efficient utilization and conversion of sulfur under the realistic condition of high-sulfur content and low electrolyte/sulfur ratio.Rational design of heterostructure electrocatalysts with abundant active sites and strong interfacial electronic interactions is a promising but still challenging strategy for preventing shuttling of polysulfides in lithium-sulfur batteries.Herein,ultrathin nonlayered NiO/Ni_(3)S_(2)heterostructure nanosheets are developed through topochemical transformation of layered Ni(OH)_(2)templates to improve the utilization of sulfur and facilitate stable cycling of batteries.As a multifunction catalyst,NiO/Ni_(3)S_(2)not only enhances the adsorption of polysulfides and shorten the transport path of Li ions and electrons but also promotes the Li_(2)S formation and transformation,which are verified by both in-situ Raman spectroscopy and electrochemical investigations.Thus,the cell with NiO/Ni_(3)S_(2)as electrocatalyst delivers an area capacity of 4.8 mAh cm^(-2)under the high sulfur loading(6 mg cm^(-2))and low electrolyte/sulfur ratio(4.3 pL mg^(-1)).The strategy can be extended to 2D Ni foil,demonstrating its prospects in the construction of electrodes with high gravimetric/volumetric energy densities.The designed electrocatalyst of ultrathin nonlayered heterostructure will shed light on achieving high energy density lithium-sulfur batteries.展开更多
A prerequisite for widespread applications of atomically thin transition metal dichalcogenides in future electronics is to achieve reliable electrical contacts,which is of considerable challenge due to the difficultie...A prerequisite for widespread applications of atomically thin transition metal dichalcogenides in future electronics is to achieve reliable electrical contacts,which is of considerable challenge due to the difficulties in selectively doping and inevitable physical damages of these atomically thin materials during typical metal integration process.Here,we report the in situ growth of ultrathin metallic NiSe single crystals on WSe2 in which the metallic NiSe nanosheets function as the contact electrodes to WSe2,creating an interface that is essentially free from chemical disorder.The NiSe/WSe2 heterostructures also exhibit well-aligned lattice orientation between the two layers,forming a periodic Moire pattern.Electrical transport studies demonstrate that the NiSe nanosheets exhibit an excellent metallic feature,as evidenced by the extra-high electrical conductivity of up to 1.6×10^6 S-nf1.The WSe2 transistors with the NiSe contact show field-effect mobilities (/vFe) more than double that with Cr/Au electrodes.This study demonstrates an effective pathway to achieve reliable electrical contacts to the atomically thin 2D materials,and maybe readily extended for fabricating 2D/2D low-resistance contacts for a variety of transition metal dichalcogenides.展开更多
Two-dimensional(2D)magnetic crystals with intrinsic ferromagnetism are highly desirable for novel spin-electronic devices.However,the controllable synthesis of 2D magnets,especially the direct growth of 2D magnets on ...Two-dimensional(2D)magnetic crystals with intrinsic ferromagnetism are highly desirable for novel spin-electronic devices.However,the controllable synthesis of 2D magnets,especially the direct growth of 2D magnets on substrate surfaces,is still a challenge.Here,we demonstrate the synthesis of ultrathin zinc-blende phase manganese selenide(β-MnSe)nanosheets using the chemical vapor deposition(CVD)technique.The 2Dβ-MnSe crystals exhibit distinct ferromagnetic properties with a Curie temperature of 42.3 K.Density functional theory(DFT)calculations suggest that the ferromagnetic order inβ-MnSe originates from the exchange coupling between the unsaturated Se and Mn atoms.This study presents significant progress in the CVD growth of ultrathin 2D magnetic materials by thinning bulk magnets,and it will pave the way for the building of energy-efficient spintronic devices in the future.展开更多
Two-dimensional(2D)indium arsenide(InAs)is promising for future electronic and optoelectronic applications such as highperformance nanoscale transistors,flexible and wearable devices,and high-sensitivity broadband pho...Two-dimensional(2D)indium arsenide(InAs)is promising for future electronic and optoelectronic applications such as highperformance nanoscale transistors,flexible and wearable devices,and high-sensitivity broadband photodetectors,and is advantageous for its heterogeneous integration with Si-based electronics.However,the synthesis of 2D InAs single crystals is challenging because of the nonlayered structure.Here we report the van der Waals epitaxy of 2D InAs single crystals,with their thickness down to 4.8 nm,and their lateral sizes up to~37μm.The as-grown InAs flakes have high crystalline quality and are homogenous.The thickness can be tuned by growth time and temperature.Moreover,we explore the thickness-dependent optical properties of InAs flakes.Transports measurement reveals that 2D InAs possesses high conductivity and high carrier mobility.Our work introduces InAs to 2D materials family and paves the way for applying 2D InAs in high-performance electronics and optoelectronics.展开更多
Designing hierarchical heterostructure to optimize the adsorption of hydrogen intermediate(H*)is impressive for hydrogen evolution reaction(HER)catalysis.Herein,we show that vertically mounting two-dimensional(2D)laye...Designing hierarchical heterostructure to optimize the adsorption of hydrogen intermediate(H*)is impressive for hydrogen evolution reaction(HER)catalysis.Herein,we show that vertically mounting two-dimensional(2D)layered molybdenum disulfide(MoS_(2))nanosheets on 2D nonlayered dimolybdenum carbide(Mo_(2)C)nanomeshes to form a hierarchical heterostructure largely accelerates the HER kinetics in acidic electrolyte due to the weakening adsorption strength of H*on 2D Mo_(2)C nanomeshes.Our hierarchical MoS2/Mo2C heterostructure therefore gives a decrease of overpotential for up to 500 mV at-10 mA·cm^(-2)and an almost 200-fold higher kinetics current density compared with the pristine Mo2C nanomeshes and maintains robust stability with a small drop of overpotential for only 16 mV upon 5,000 cycles.We further rationalize this finding by theoretical calculations and find an optimized adsorption free energy of H*,identifying that the MoS_(2)featuring strong H*desorption plays a key role in weakening the strong binding of Mo_(2)C with H*and therefore improves the intrinsic HER activity on active C sites of Mo_(2)C.This present finding shines the light on the rational design of heterostructured catalysts with synergistic geometry.展开更多
Combining the physical advantages of two-dimensional(2D)inorganic nanosheets and the modular design and programmed structure of metal-organic frameworks(MOFs),2D MOFs remain at the forefront of functional material res...Combining the physical advantages of two-dimensional(2D)inorganic nanosheets and the modular design and programmed structure of metal-organic frameworks(MOFs),2D MOFs remain at the forefront of functional material research.Despite tremendous efforts,precise control in the synthesis of 2D nonlayered MOFs with predesigned topology for desired applications remains challenging.Success in the bottom-up synthesis of 2D nonlayered MOFs via ligand exchange motivated us to incorporate partial BTC(BTC=1,3,5-benzenetricarboxylate)ligand dissociation and CO_(2) capped coordination into the top-down treatment of bulk Cu-BTC MOF,leading to successful conversion of a 3D nonlayered network to a 2D Cu-based topological structure.Notably,a supercritical CO_(2)-containing solvent mixture is employed to provide the desired defect and coordination engineering.Thus,our work introduces a new top-down concept based on modulated synthesis to fabricate high-quality 2D nonlayered MOFs for the first time.展开更多
基金This work was supported by National Natural Science Foundation of China(21825103,11774044,52072059)the Hubei Provincial Natural Science Foundation of China(2019CFA002)+1 种基金the Fundamental Research Funds for the Central Universities(2019kfyXMBZ018 and 2020kfyXJJS050)We also thank the technical support from Analytical and Testing Center in Huazhong University of Science and Technology.
文摘Nonlayered two-dimensional(2D)materials have attracted increasing attention,due to novel physical properties,unique surface structure,and high compatibility with microfabrication technique.However,owing to the inherent strong covalent bonds,the direct synthesis of 2D planar structure from nonlayered materials,especially for the realization of large-size ultrathin 2D nonlayered materials,is still a huge challenge.Here,a general atomic substitution conversion strategy is proposed to synthesize large-size,ultrathin nonlayered 2D materials.Taking nonlayered CdS as a typical example,large-size ultrathin nonlayered CdS single-crystalline flakes are successfully achieved via a facile low-temperature chemical sulfurization method,where pre-grown layered CdI2 flakes are employed as the precursor via a simple hot plate assisted vertical vapor deposition method.The size and thickness of CdS flakes can be controlled by the CdI2 precursor.The growth mechanism is ascribed to the chemical substitution reaction from I to S atoms between CdI2 and CdS,which has been evidenced by experiments and theoretical calculations.The atomic substitution conversion strategy demonstrates that the existing 2D layered materials can serve as the precursor for difficult-to-synthesize nonlayered 2D materials,providing a bridge between layered and nonlayered materials,meanwhile realizing the fabrication of large-size ultrathin nonlayered 2D materials.
基金supported by the Science and Technology Plan Project of Tangshan Science and Technology Bureau(No.22130217H)the Natural Science Foundation-Steel and Iron Foundation of Hebei Province(No.E2022209114)the Open Research Fund from Guangxi Key Laboratory of Information Materials,Guilin University of Electronic Technology(No.221004-K).
文摘Two-dimensional(2D)MoO_(2),a binary nonlayered material,has been extensively studied for potential applications in catalysis and electronics.However,the preparation of 2D MoO_(2) remains challenging.Herein,we report the growth of 2D MoO_(2) flakes with rhombic morphology on the sapphire substrate via a chemical vapor deposition(CVD)method.Atomic force microscopy shows the CVDgrown MoO_(2) flakes with thin thickness.The CVD-obtained MoO_(2) with a stoichiometric ratio of 1:2 is verified using energy-dispersive X-ray spectroscopy.Scanning transmission electron microscopy(STEM)characterization reveals the high-quality,single-crystal nature of the CVDderived 2D MoO_(2) flakes.
基金supported by the National Natural Science Foundation of China(Grant nos.62090013,61974043,and 91833303)the National Key R&D Program of China(Grant no.2019YFB2203403)+1 种基金the Projects of Science and Technology Commission of Shanghai Municipality(Grant nos.21JC1402100 and 19511120100)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning.
文摘The practical application of Lithium-Sulfur batteries largely depends on highly efficient utilization and conversion of sulfur under the realistic condition of high-sulfur content and low electrolyte/sulfur ratio.Rational design of heterostructure electrocatalysts with abundant active sites and strong interfacial electronic interactions is a promising but still challenging strategy for preventing shuttling of polysulfides in lithium-sulfur batteries.Herein,ultrathin nonlayered NiO/Ni_(3)S_(2)heterostructure nanosheets are developed through topochemical transformation of layered Ni(OH)_(2)templates to improve the utilization of sulfur and facilitate stable cycling of batteries.As a multifunction catalyst,NiO/Ni_(3)S_(2)not only enhances the adsorption of polysulfides and shorten the transport path of Li ions and electrons but also promotes the Li_(2)S formation and transformation,which are verified by both in-situ Raman spectroscopy and electrochemical investigations.Thus,the cell with NiO/Ni_(3)S_(2)as electrocatalyst delivers an area capacity of 4.8 mAh cm^(-2)under the high sulfur loading(6 mg cm^(-2))and low electrolyte/sulfur ratio(4.3 pL mg^(-1)).The strategy can be extended to 2D Ni foil,demonstrating its prospects in the construction of electrodes with high gravimetric/volumetric energy densities.The designed electrocatalyst of ultrathin nonlayered heterostructure will shed light on achieving high energy density lithium-sulfur batteries.
基金the financial support from the Fundamental Research Funds of the Central Universities (No.531107051078)the Double First-Class University In让iative of Hunan University (No.531109100004)+2 种基金the 111 Project of China (No.D17003)the support from the National Natural Science Foundation of China (No.751214296,51802090,61874041,and 61804050)Hunan Key Laboratory of Two-Dimensional Materials (No.801200005).
文摘A prerequisite for widespread applications of atomically thin transition metal dichalcogenides in future electronics is to achieve reliable electrical contacts,which is of considerable challenge due to the difficulties in selectively doping and inevitable physical damages of these atomically thin materials during typical metal integration process.Here,we report the in situ growth of ultrathin metallic NiSe single crystals on WSe2 in which the metallic NiSe nanosheets function as the contact electrodes to WSe2,creating an interface that is essentially free from chemical disorder.The NiSe/WSe2 heterostructures also exhibit well-aligned lattice orientation between the two layers,forming a periodic Moire pattern.Electrical transport studies demonstrate that the NiSe nanosheets exhibit an excellent metallic feature,as evidenced by the extra-high electrical conductivity of up to 1.6×10^6 S-nf1.The WSe2 transistors with the NiSe contact show field-effect mobilities (/vFe) more than double that with Cr/Au electrodes.This study demonstrates an effective pathway to achieve reliable electrical contacts to the atomically thin 2D materials,and maybe readily extended for fabricating 2D/2D low-resistance contacts for a variety of transition metal dichalcogenides.
基金National Natural Science Foundation of China,Grant/Award Numbers:11828401,11964024,21971113Startup Project of Inner Mongolia University,Grant/Award Number:21200‐5175101+6 种基金National Research Foundation–Competitive Research Program of Singapore,Grant/Award Numbers:CRP22‐2019‐0060,NRF‐CRP21‐2018‐0007,NRF2017‐ANR0022DPSfund of University of Macao,Grant/Award Numbers:MYRG2018‐00079‐IAPME,MYRG2019‐00115‐IAPMEMOE Tier 2,Grant/Award Number:MOE2017‐T2‐2‐136Tier 3,Grant/Award Number:MOE2018‐T3‐1‐002Science and Technology Development Fund of Macao SAR,Grant/Award Numbers:FDCT0059/2018/A2,FDCT009/2017/AMJFund of Shenzhen Science and Technology Innovation Committee,Grant/Award Number:SGDX20201103093600003Shanghai Pujiang Program,Grant/Award Number:20PJ1411500。
文摘Two-dimensional(2D)magnetic crystals with intrinsic ferromagnetism are highly desirable for novel spin-electronic devices.However,the controllable synthesis of 2D magnets,especially the direct growth of 2D magnets on substrate surfaces,is still a challenge.Here,we demonstrate the synthesis of ultrathin zinc-blende phase manganese selenide(β-MnSe)nanosheets using the chemical vapor deposition(CVD)technique.The 2Dβ-MnSe crystals exhibit distinct ferromagnetic properties with a Curie temperature of 42.3 K.Density functional theory(DFT)calculations suggest that the ferromagnetic order inβ-MnSe originates from the exchange coupling between the unsaturated Se and Mn atoms.This study presents significant progress in the CVD growth of ultrathin 2D magnetic materials by thinning bulk magnets,and it will pave the way for the building of energy-efficient spintronic devices in the future.
基金supported by the National Key Basic Research Program of China(No.2021YFA1401400)the start-up funds of Shanghai Jiao Tong University,the National Natural Science Foundation of China(Nos.52103344,52031014,22022507,and 51973111)+1 种基金the National Key Research and Development Program of China(No.2017YFA0206301)Beijing National Laboratory for Molecular Sciences(No.BNLMS202004).
文摘Two-dimensional(2D)indium arsenide(InAs)is promising for future electronic and optoelectronic applications such as highperformance nanoscale transistors,flexible and wearable devices,and high-sensitivity broadband photodetectors,and is advantageous for its heterogeneous integration with Si-based electronics.However,the synthesis of 2D InAs single crystals is challenging because of the nonlayered structure.Here we report the van der Waals epitaxy of 2D InAs single crystals,with their thickness down to 4.8 nm,and their lateral sizes up to~37μm.The as-grown InAs flakes have high crystalline quality and are homogenous.The thickness can be tuned by growth time and temperature.Moreover,we explore the thickness-dependent optical properties of InAs flakes.Transports measurement reveals that 2D InAs possesses high conductivity and high carrier mobility.Our work introduces InAs to 2D materials family and paves the way for applying 2D InAs in high-performance electronics and optoelectronics.
基金The authors thank the supports from the Fundamental Research Funds for the Central Universities(No.40120631)the Zhejiang Provincial Natural Science Foundation(Nos.LQ22B060003 and LY20E020004)+1 种基金the Fundamental Research Funds for the Provincial Universities of Zhejiang(No.2020YQ005)the Research Foundation of Talented Scholars of Zhejiang A&F University(No.2020FR069).
文摘Designing hierarchical heterostructure to optimize the adsorption of hydrogen intermediate(H*)is impressive for hydrogen evolution reaction(HER)catalysis.Herein,we show that vertically mounting two-dimensional(2D)layered molybdenum disulfide(MoS_(2))nanosheets on 2D nonlayered dimolybdenum carbide(Mo_(2)C)nanomeshes to form a hierarchical heterostructure largely accelerates the HER kinetics in acidic electrolyte due to the weakening adsorption strength of H*on 2D Mo_(2)C nanomeshes.Our hierarchical MoS2/Mo2C heterostructure therefore gives a decrease of overpotential for up to 500 mV at-10 mA·cm^(-2)and an almost 200-fold higher kinetics current density compared with the pristine Mo2C nanomeshes and maintains robust stability with a small drop of overpotential for only 16 mV upon 5,000 cycles.We further rationalize this finding by theoretical calculations and find an optimized adsorption free energy of H*,identifying that the MoS_(2)featuring strong H*desorption plays a key role in weakening the strong binding of Mo_(2)C with H*and therefore improves the intrinsic HER activity on active C sites of Mo_(2)C.This present finding shines the light on the rational design of heterostructured catalysts with synergistic geometry.
基金the National Natural Science Foundation of China(Grants No.51173170,21571157,21703207,21773216,21903070,and U2004208).
文摘Combining the physical advantages of two-dimensional(2D)inorganic nanosheets and the modular design and programmed structure of metal-organic frameworks(MOFs),2D MOFs remain at the forefront of functional material research.Despite tremendous efforts,precise control in the synthesis of 2D nonlayered MOFs with predesigned topology for desired applications remains challenging.Success in the bottom-up synthesis of 2D nonlayered MOFs via ligand exchange motivated us to incorporate partial BTC(BTC=1,3,5-benzenetricarboxylate)ligand dissociation and CO_(2) capped coordination into the top-down treatment of bulk Cu-BTC MOF,leading to successful conversion of a 3D nonlayered network to a 2D Cu-based topological structure.Notably,a supercritical CO_(2)-containing solvent mixture is employed to provide the desired defect and coordination engineering.Thus,our work introduces a new top-down concept based on modulated synthesis to fabricate high-quality 2D nonlayered MOFs for the first time.
