Heat dissipation and thermal switches are vital for adaptive cooling and extending the lifespan of electronic devices and batteries. In this work, we conducted high-throughput investigations on the thermal transport o...Heat dissipation and thermal switches are vital for adaptive cooling and extending the lifespan of electronic devices and batteries. In this work, we conducted high-throughput investigations on the thermal transport of 24 experimentally realized two-dimensional(2D) materials and their potential as thermal switches, leveraging machine-learning-assisted strain engineering and phonon transport simulations. We identified several highperformance thermal switches with ratios exceeding 2, with germanene(Ge) achieving an ultrahigh ratio of up to9.64 within the reversible deformation range. The underlying mechanism is strain-induced bond softening, which sensitively affects anharmonicity represented by three-and four-phonon scattering. The widespread occurrence of four-phonon scattering was confirmed in the thermal transport of 2D materials. Opposite switching trends were discovered, with 2D transition metal dichalcogenide materials showing negative responses to tensile strain while buckled 2D elemental materials showed positive responses. We further proposed a screening descriptor based on strain-induced changes in the Gr¨uneisen parameter for efficiently identifying new high-performance thermal switch materials. This work establishes a paradigm for thermal energy control in 2D materials through strain engineering, which may be experimentally realized in the future via bending, substrate mismatch, and related approaches, thereby laying a robust foundation for further developments and applications.展开更多
The precise control of wrinkles and strain gradients in nanofilm is of significant interest due to their profound influence on electronic band structures and spin states.Here,we employ ultrafast electron diffraction(U...The precise control of wrinkles and strain gradients in nanofilm is of significant interest due to their profound influence on electronic band structures and spin states.Here,we employ ultrafast electron diffraction(UED)to study the picosecond-scale dynamics of laser-induced bending in 2H-MoTe2 thin films.展开更多
CONSPECTUS:Two-dimensional(2D)materials form a large and diverse family of materials with extremely rich compositions,ranging from graphene to complex transition metal derivatives.They exhibit unique physical,chemical...CONSPECTUS:Two-dimensional(2D)materials form a large and diverse family of materials with extremely rich compositions,ranging from graphene to complex transition metal derivatives.They exhibit unique physical,chemical,and electronic properties,making 2D materials highly promising in the fields of sustainable energy storage and electrocatalysis.Although significant progress has been made in the design and performance optimization of 2D materials,challenges persist,particularly in energy storage and electrocatalysis.A key issue is the restacking or aggregation of these materials in the powder form,which hinders ion transport and reduces their overall performance by limiting the effective surface area.展开更多
Transmission electron microscopy(TEM)is an indispensable tool for elucidating the intrinsic atomic structures of materials and provides deep insights into defect dynamics,phase transitions,and nanoscale structural det...Transmission electron microscopy(TEM)is an indispensable tool for elucidating the intrinsic atomic structures of materials and provides deep insights into defect dynamics,phase transitions,and nanoscale structural details.While numerous intriguing physical properties have been revealed in recently discovered two-dimensional(2D)quantummaterials,many exhibit significant sensitivity towater and oxygen under ambient conditions.This inherent instability complicates sample preparation for TEM analysis and hinders accurate property measurements.This review highlights recent technical advancements to preserve the intrinsic structures of water-and oxygen-sensitive 2D materials for atomic-scale characterizations.A critical development discussed in this review is implementing an inert gas-protected glovebox integrated system(GIS)designed specifically for TEM experiments.In addition,this review emphasizes air-sensitivematerials such as 2D transitionmetal dichalcogenides,transition metal dihalides and trihalides,and low-dimensional magnetic materials,demonstrating breakthroughs in overcoming their environmental sensitivity.Furthermore,the progress in TEM characterization enabled by the GIS is analyzed to provide a comprehensive overview of state-of-the-art methodologies in this rapidly advancing field.展开更多
Two-dimensional(2D)transition metal dichalcogenides(TMDs),which allow atomic-scale manipulation,have supe-rior electrical and optical properties that challenge the limits of traditional bulk semiconductors like silico...Two-dimensional(2D)transition metal dichalcogenides(TMDs),which allow atomic-scale manipulation,have supe-rior electrical and optical properties that challenge the limits of traditional bulk semiconductors like silicon^([1,2]).As a repre-sentative TMD and a promising 2D channel material for high-performance,scalable p-type transistors,tungsten diselenide(WSe_(2))has attracted considerable academic and industrial interest for its potential in advanced complementary metal−oxide−semiconductor(CMOS)logic technology and in extending Moore’s Law^([3−7]).展开更多
Dramatic fluorescence enhancement in two-dimensional(2D)van der Waals materials(vdWMs)coupled to plasmonic nanostructures has the potential to enable ultrathin,flexible,and high-brightness illumination devices.However...Dramatic fluorescence enhancement in two-dimensional(2D)van der Waals materials(vdWMs)coupled to plasmonic nanostructures has the potential to enable ultrathin,flexible,and high-brightness illumination devices.However,addressing the limitation of locally scattered small plasmon-enhanced areas remains challenging.Here,we present a 2D plasmonic enhancement of photoluminescence(PL)spanning nearly 800μm^(2),enabled by surface lattice resonance(SLR)in a 2D vdWM-Au slot lattice hybrid.The Au slot lattice is designed and fabricated using Babinet’s principle and Rayleigh’s anomaly to maximize radiative decay rate and induce non-local photo-excitation in a MoSe_(2)monolayer.For emitted PL coupled with SLR,enhanced by up to 32-fold,we investigate its in-plane directivity and long-range propagation using angle-and space-resolved spectroscopic PL measurements.Our experiment reveals that a nearly 800μm^(2)2D luminescent sheet can be achieved regardless of the size of the MoSe_(2)crystal,even with a sub-μm^(2)flake.This work provides a new type of ultrabright,large-area 2D luminescent material,suitable for a range of optical illumination,communication,and sensing devices.展开更多
Based on the nonlinear saturable absorption properties(NSAPs)of a two-dimensional(2D)material of antimony selenide(Sb_(2)Se_(3)),a Q-switched erbium-doped fiber(EDF)laser is systematically demonstrated.The Sb_(2)Se_(3...Based on the nonlinear saturable absorption properties(NSAPs)of a two-dimensional(2D)material of antimony selenide(Sb_(2)Se_(3)),a Q-switched erbium-doped fiber(EDF)laser is systematically demonstrated.The Sb_(2)Se_(3)nano sheets are prepared by liquid-phase exfoliation(LPE)method.After the sandwich-structured Sb_(2)Se_(3)saturable absorber(SA)is fabricated,the NSAPs are characterized and the modulation depth,the saturation intensity and the unsaturated loss are determined to be 25.2%,2.02 MW/cm^(2),and 3.29%,respectively.When the as-prepared Sb_(2)Se_(3)-SA is integrated into the ring cavity,the laser operates at a stable Q-switching regime in the pump power range of 100—400 mW.The laser oscillates at the central wavelength of 1558.48 nm with a 3 dB bandwidth of 2.32 nm.Take the advantages of the Sb_(2)Se_(3)-SA,the pulse duration can be compressed from 40.49 kHz to 128.12 kHz.At the pump power of 400 mW,the Q-switching laser gives the narrowest pulse duration the highest average output power,the largest pulse energy,and the signal-to-noise ratio(SNR)of 0.93μs,2.16 mW,16.89 nJ,and 53 dB,respectively.Our new attempt on Sb_(2)Se_(3)-based Q-switched EDF laser,combining the existing mode-locking achievements,proves that Sb_(2)Se_(3)is a powerful candidate for pulse compression due to the characteristics of high modulation depth and high stability.展开更多
Rechargeable lithium-sulfur(Li-S)batteries have attracted significant research attention due to their high capacity and energy density.However,their commercial applications are still hindered by challenges such as the...Rechargeable lithium-sulfur(Li-S)batteries have attracted significant research attention due to their high capacity and energy density.However,their commercial applications are still hindered by challenges such as the shuttle effect of soluble lithium sulfide species,the insulating nature of sulfur,and the fast capacity decay of the electrodes.Various efforts are devoted to address these problems through questing more conductive hosts with abundant polysulfide chemisorption sites,as well as modifying the separators to physically/chemically retard the polysulfides migration.Two dimensional transition metal carbides,carbonitrides and nitrides,so-called MXenes,are ideal for confining the polysulfides shuttling effects due to their high conductivity,layered structure as well as rich surface terminations.As such,MXenes have thus been widely studied in Li-S batteries,focusing on the conductive sulfur hosts,polysulfides interfaces,and separators.Therefore,in this review,we summarize the significant progresses regarding the design of multifunctional MXene-based Li-S batteries and discuss the solutions for improving electrochemical performances in detail.In addition,challenges and perspectives of MXenes for Li-S batteries are also outlined.展开更多
In this study,we have developed a high-sensitivity,near-infrared photodetector based on PdSe2/GaAs heterojunction,which was made by transferring a multilayered PdSe2 film onto a planar GaAs.The as-fabricated PdSe2/GaA...In this study,we have developed a high-sensitivity,near-infrared photodetector based on PdSe2/GaAs heterojunction,which was made by transferring a multilayered PdSe2 film onto a planar GaAs.The as-fabricated PdSe2/GaAs heterojunction device exhibited obvious photovoltaic behavior to 808 nm illumination,indicating that the near-infrared photodetector can be used as a self-driven device without external power supply.Further device analysis showed that the hybrid heterojunction exhibited a high on/off ratio of 1.16×10^5 measured at 808 nm under zero bias voltage.The responsivity and specific detectivity of photodetector were estimated to be 171.34 mA/W and 2.36×10^11 Jones,respectively.Moreover,the device showed excellent stability and reliable repeatability.After 2 months,the photoelectric characteristics of the near-infrared photodetector hardly degrade in air,attributable to the good stability of the PdSe2.Finally,the PdSe2/GaAs-based heterojunction device can also function as a near-infrared light sensor.展开更多
Two-dimensional（2 D） materials have attracted increasing attentions recently due to their unique physical and chemical properties. We herein report the synthesis of four chemically stable 2 D covalent organic nanosh...Two-dimensional（2 D） materials have attracted increasing attentions recently due to their unique physical and chemical properties. We herein report the synthesis of four chemically stable 2 D covalent organic nanosheets（CONs） with large lateral sizes（up to 200 mm） and high aspect ratios（〉20 000） at the air-water interface through the Langmuir-Blodgett method. These CONs exhibit good crystallinity proved by high resolution transmission electron microscopy（HRTEM） and selected area electron diffraction（SAED）. In addition, the hydrophobicity of these CONs can be systematically adjusted by the introduction of various functional groups, making them suitable as functional coating and membrane materials.展开更多
The synthesis of high-quality ultrathin overlayers is critically dependent on the surface structure of substrates,especially involving the overlayer–substrate interaction.By using in situ surface measurements,we demo...The synthesis of high-quality ultrathin overlayers is critically dependent on the surface structure of substrates,especially involving the overlayer–substrate interaction.By using in situ surface measurements,we demonstrate that the overlayer–substrate interaction can be tuned by doping near-surface Ar nanobubbles.The interfacial coupling strength significantly decreases with near-surface Ar nanobubbles,accompanying by an“anisotropic to isotropic”growth transformation.On the substrate containing near-surface Ar,the growth front crosses entire surface atomic steps in both uphill and downhill directions with no difference,and thus,the morphology of the two-dimensional(2D)overlayer exhibits a round-shape.Especially,the round-shaped 2D overlayers coalesce seamlessly with a growth acceleration in the approaching direction,which is barely observed in the synthesis of 2D materials.This can be attributed to the immigration lifetime and diffusion rate of growth species,which depends on the overlayer–substrate interaction and the surface catalysis.Furthermore,the“round to hexagon”morphological transition is achieved by etching-regrowth,revealing the inherent growth kinetics under quasi-freestanding conditions.These findings provide a novel promising way to modulate the growth,coalescence,and etching dynamics of 2D materials on solid surfaces by adjusting the strength of overlayer–substrate interaction,which contributes to optimization of large-scale production of 2D material crystals.展开更多
Hexagonal boron nitride nanosheets(HBNNSs)have huge potential in the field of coating materials owing to their remarkable chemical stability,mechanical strength and thermal conductivity.Thin-layer hBNNSs were obtained...Hexagonal boron nitride nanosheets(HBNNSs)have huge potential in the field of coating materials owing to their remarkable chemical stability,mechanical strength and thermal conductivity.Thin-layer hBNNSs were obtained by a liquid-phase exfoliation of h-BN powders and incorporated into EVA coatings for improving the safety performance of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).HBNNSs and ethylene-vinyl acetate copolymer(EVA)were introduced to HMX by a solvent-slurry process.For comparison,the HMX/EVA and HMX/EVA/graphene(HMX/EVA/G)composites were also prepared by a similar process.The morphology,crystal form,surface element distribution,thermal decomposition property and impact sensitivity of HMX/EVA/hBNNSs composites were contrastively investigated.Results showed that as prepared HMX/EVA/hBNNSs composites were well coated with hBNNSs and EVA,and exhibited better thermal stability and lower impact sensitivity than that of HMX/EVA and HMX/EVA/G composites,suggesting superior performance of desensitization of hBNNSs in explosives.展开更多
Graphdiyne(GDY),a rising star of carbon allotrope with sp-/sp?.hybridized one-atom-thick all-carbon two-dimensional(2D)network,has shown numerous unique structure and fascinating properties.Since the first successful ...Graphdiyne(GDY),a rising star of carbon allotrope with sp-/sp?.hybridized one-atom-thick all-carbon two-dimensional(2D)network,has shown numerous unique structure and fascinating properties.Since the first successful synthesis of GDY in 2010,GDY research has made a series of great progresses,and promoted the fundamental researches and practical applications in various fields of chemistry,physics,information science,material science,life science and environmental science and so on.展开更多
Due to their reduced dimensionality and strong quantumconfinement, two-dimensional (2D) materials have emerged as aversatile platform for exploring quantum phenomena absent intheir bulk counterparts. Stacking 2D mater...Due to their reduced dimensionality and strong quantumconfinement, two-dimensional (2D) materials have emerged as aversatile platform for exploring quantum phenomena absent intheir bulk counterparts. Stacking 2D materials to form bilayerheterostructures or homostructures introduces additionaldegrees of freedom to tune or even create novel quantumproperties [1]. A prominent example is the discovery of flatbands and superconductivity in twisted bilayer graphene at asmall “magic” twist angle, where suppressed electron kineticsamplifies electron correlation, giving rise to emergent quantumphenomena [2]. Another notable case is the formation of quasicrystalsin bilayer graphene at the large twist angle, whichfurther expands the possibilities for tailoring electronic structures[3].展开更多
Exploring new strategies to broaden the upper/lower limit of thermal conductivity is of great interest to develop thermal management materials that can adapt to extreme environments.In this work,we employ an interfaci...Exploring new strategies to broaden the upper/lower limit of thermal conductivity is of great interest to develop thermal management materials that can adapt to extreme environments.In this work,we employ an interfacial ion regulation to enhance the thermal insulation performance of 2D layered double hydroxide nanosheets.The introduction of interfacial ion enlarges the interplanar spacing of Co(OH)_(2) nanosheets from 4.64 to 8.05 ?,which reduces phonon scattering length perpendicular to the two-dimensional plane and leads to enhanced interlayer thermal insulation.The interfacial ion-regulated Co(OH)_(2)(named as Co(OH)_(2)-M^(x-)) exhibits 3-fold enhancement of thermal insulation through decreasing the thermal conductivity to as low as 0.15 W m^(-1) K^(-1),which is among the top values in 2D solid materials.We anticipate that interfacial ion regulation for 2D nanosheets paves a new avenue to break through the thermal insulation limit.展开更多
Two‐dimensional transition metal dichalcogenides(TMDs)play host to a wide range of novel topological states,such as quantum spin Hall insulators,superconductors,and Weyl semimetals.The rich polymorphism in TMDs sugge...Two‐dimensional transition metal dichalcogenides(TMDs)play host to a wide range of novel topological states,such as quantum spin Hall insulators,superconductors,and Weyl semimetals.The rich polymorphism in TMDs suggests that phase engineering can be used to switch between different charge order states.Intercalation of atoms or molecules into the van der Waals gap of TMDs has emerged as a powerful approach to modify the properties of the material,leading to phase transition or the formation of substoichiometric phases via compositional tuning,thus broadening the electronic and optical landscape of these materials for a wide range of applications.Here,we review the current efforts in the preparation of intercalated TMD.The challenges and opportunities for intercalated TMDs to create a new device paradigm for material science are discussed.展开更多
Black phosphorus(BP),especially for BP nanosheets,with unique layered structure among two dimensional(2D)materials has attracted much attention due to its outstanding physical properties,such as ultra-high mobility,in...Black phosphorus(BP),especially for BP nanosheets,with unique layered structure among two dimensional(2D)materials has attracted much attention due to its outstanding physical properties,such as ultra-high mobility,in-plane anisotropic properties.However,the small horizontal-size of reported BP limits its applications in the integrated circuit or some functional devices.In this work,a solvothermalassisted liquid-phase exfoliation technique is firstly employed for preparing large size and high-quality BP nanosheets.In the high-polar acetonitrile solvent,solvothermal treatment weakens the Van der Waals forces of block BP.Together with the subsequently ultrasonic processing,effective exfoliation of large size and high-quality BP nanosheets are realized.The TEM,AFM and Raman results indicate that the prepared BP nanosheets are high quality with an average thickness of about 2 nm,and the horizontalsize is up to 10μm.This facile and effective method for exfoliated BP nanosheets provides a promising strategy for the exfoliation of other 2D materials.展开更多
Two-dimensional transition metal dichalcogenide semiconductors have emerged as promising candidates for optoelectronic devices with unprecedented properties and ultra-compact footprints. However, the high sensitivity ...Two-dimensional transition metal dichalcogenide semiconductors have emerged as promising candidates for optoelectronic devices with unprecedented properties and ultra-compact footprints. However, the high sensitivity of atomically thin materials to the surrounding dielectric media imposes severe limitations on their practical applicability. Hence, to enable the effective integration of these materials in devices, the development of reliable encapsulation procedures that preserve their physical properties is required. Here, the excitonic photoluminescence （at room temperature and 10 K） is assessed on mechanically exfoliated WSe2 monolayer flakes encapsulated with SiOx and AlxOy layers by means of chemical and physical deposition techniques. Conformal coating on untreated and non- functionalized flakes is successfully achieved by all the techniques examined, with the exception of atomic layer deposition, for which a cluster-like oxide coating is formed. No significant compositional or strain state changes in the flakes are detected upon encapsulation, independently of the technique adopted. Remarkably, our results show that the optical emission of the flakes is strongly influenced by the stoichiometry quality of the encapsulating oxide. When the encapsulation is carried out with slightly sub-stoichiometric oxides, two remarkable phenomena are observed. First, dominant trion （charged exciton） photoluminescence is detected at room temperature, revealing a clear electrical doping of the monolayers. Second, a strong decrease in the optical emission of the monolayers is observed, and attributed to non-radiative recombination processes and/or carrier transfer from the flake to the oxide. Power- and temperature-dependent photoluminescence measurements further confirm that stoichiometric oxides obtained by physical deposition lead to a successful encapsulation, opening a promising route for the development of integrated two-dimensional devices.展开更多
基金supported bythe Science and Technology Commission of Shanghai Municipality (Grant No.24CL2901702)The numerical calculations were performed at the Supercomputer Center (Project No.2024-Cb-0042)Institute for Solid State Physics,the University of Tokyo。
文摘Heat dissipation and thermal switches are vital for adaptive cooling and extending the lifespan of electronic devices and batteries. In this work, we conducted high-throughput investigations on the thermal transport of 24 experimentally realized two-dimensional(2D) materials and their potential as thermal switches, leveraging machine-learning-assisted strain engineering and phonon transport simulations. We identified several highperformance thermal switches with ratios exceeding 2, with germanene(Ge) achieving an ultrahigh ratio of up to9.64 within the reversible deformation range. The underlying mechanism is strain-induced bond softening, which sensitively affects anharmonicity represented by three-and four-phonon scattering. The widespread occurrence of four-phonon scattering was confirmed in the thermal transport of 2D materials. Opposite switching trends were discovered, with 2D transition metal dichalcogenide materials showing negative responses to tensile strain while buckled 2D elemental materials showed positive responses. We further proposed a screening descriptor based on strain-induced changes in the Gr¨uneisen parameter for efficiently identifying new high-performance thermal switch materials. This work establishes a paradigm for thermal energy control in 2D materials through strain engineering, which may be experimentally realized in the future via bending, substrate mismatch, and related approaches, thereby laying a robust foundation for further developments and applications.
基金supported by the High-level Talent Research Start-up Project Funding of Henan Academy of Sciences(Project No.241827012)the National Natural Science Foundation of China(Grant Nos.U22A6005 and 62271450)+1 种基金the National Key Research and Development Program of China(Grant Nos.2021YFA1301502,2024YFA1408701,and 2024YFA1408403)the Synergetic Extreme Condition User Facility(SECUF,https://cstr.cn/31123.02.SECUF)。
文摘The precise control of wrinkles and strain gradients in nanofilm is of significant interest due to their profound influence on electronic band structures and spin states.Here,we employ ultrafast electron diffraction(UED)to study the picosecond-scale dynamics of laser-induced bending in 2H-MoTe2 thin films.
基金support from the National Natural Science Foundation of China(Grants 22125903,22439003,22209173,22309176 and 22409196)the National Key R&D Program of China(Grant 2023YFB4005204)+6 种基金the Science and Technology Major Project of Liaoning Province(Grant No.2024JH1/11700012)the Energy Revolution S&T Program of Yulin Innovation Institute of Clean Energy(Grant E411050316)Liaoning Binhai Laboratory(Grant No.LBLD-2024-04)DICP(DICP I202471,DICP I202460)the State Key Laboratory of Catalysis(No.2024SKL-A-001)China National Postdoctoral Program for Innovative Talents(BX20240361)the Natural Science Foundation of Liaoning Province(2023BS006 and 2024-BSBA-31).
文摘CONSPECTUS:Two-dimensional(2D)materials form a large and diverse family of materials with extremely rich compositions,ranging from graphene to complex transition metal derivatives.They exhibit unique physical,chemical,and electronic properties,making 2D materials highly promising in the fields of sustainable energy storage and electrocatalysis.Although significant progress has been made in the design and performance optimization of 2D materials,challenges persist,particularly in energy storage and electrocatalysis.A key issue is the restacking or aggregation of these materials in the powder form,which hinders ion transport and reduces their overall performance by limiting the effective surface area.
基金supported by the National Key Basic Research and Development Program of China,China(No.2024YFA1409100)support by the National Natural Science Foundation of China,China(Nos.52473302 and 12461160252)+4 种基金Guangdong Innovative and Entrepreneurial Research Team Program,China(No.2019ZT08C044)Guangdong Basic Science Foundation,China(2023B1515120039)Shenzhen Science and Technology Program,China(No.20200925161102001)the Science,Technology and Innovation Commission of Shenzhen Municipality,China(No.ZDSYS20190902092905285)Quantum Science Strategic Special Project from the Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area,China(No.GDZX2301006).
文摘Transmission electron microscopy(TEM)is an indispensable tool for elucidating the intrinsic atomic structures of materials and provides deep insights into defect dynamics,phase transitions,and nanoscale structural details.While numerous intriguing physical properties have been revealed in recently discovered two-dimensional(2D)quantummaterials,many exhibit significant sensitivity towater and oxygen under ambient conditions.This inherent instability complicates sample preparation for TEM analysis and hinders accurate property measurements.This review highlights recent technical advancements to preserve the intrinsic structures of water-and oxygen-sensitive 2D materials for atomic-scale characterizations.A critical development discussed in this review is implementing an inert gas-protected glovebox integrated system(GIS)designed specifically for TEM experiments.In addition,this review emphasizes air-sensitivematerials such as 2D transitionmetal dichalcogenides,transition metal dihalides and trihalides,and low-dimensional magnetic materials,demonstrating breakthroughs in overcoming their environmental sensitivity.Furthermore,the progress in TEM characterization enabled by the GIS is analyzed to provide a comprehensive overview of state-of-the-art methodologies in this rapidly advancing field.
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDs),which allow atomic-scale manipulation,have supe-rior electrical and optical properties that challenge the limits of traditional bulk semiconductors like silicon^([1,2]).As a repre-sentative TMD and a promising 2D channel material for high-performance,scalable p-type transistors,tungsten diselenide(WSe_(2))has attracted considerable academic and industrial interest for its potential in advanced complementary metal−oxide−semiconductor(CMOS)logic technology and in extending Moore’s Law^([3−7]).
基金supported by the National Research Foundation of Korea(NRF)grants(RS-2023-00283500,RS-2025-00559639,RS-2024-00412690,RS-2023-00254055)the Samsung Science and Technology Foundation(SSTP-BA2102-05)+6 种基金the MSIT(Ministry of Science and ICT)under the ITRC(Information Technology Research Center)support program(IITP-2022-RS-2022-00164799)J.R.acknowledges the POSCO-POSTECH-RIST Convergence Research Center program funded by POSCO,and the National Research Foundation(NRF)grant(RS-2024-00356928)funded by the Ministry of Science and ICT(MSIT)of the Korean government.D.K.O.acknowledges the Hyundai Motor Chung Mong-Koo fellowshipJ.M.acknowledges the Presidential Sejong fellowship(RS-2023-00252778)funded by the MSIT of the Korean governmentY.Kim acknowledges the Hyundai Motor Chung Mong-Koo fellowship and the NRF PhD fellowship(NRF-2022R1A6A3A13066251)funded by the Ministry of Education(MOE)of the Korean government.T.K.and J.K.acknowledge the support from the Institute of Basic Science(IBS-R034-D1)J.K.acknowledges the support from the National Research Foundation of Korea grants(NRF-2023R1A2C2007998)supported by the MSIT(Ministry of Science and ICT),Korea,under the ITRC(Information Technology Research Center)support program(IITP-2023-RS-2022-00164799)supervised by the IITP(Institute for Information&Communications Technology Planning&EvaluationM.T.,A.N.A.,and V.K.acknowledge support from the Priority 2030 Federal Academic Leadership Program(angle-resolved measurements)and the Russian Science Foundation,project 22-72-10047(sample fabrication).
文摘Dramatic fluorescence enhancement in two-dimensional(2D)van der Waals materials(vdWMs)coupled to plasmonic nanostructures has the potential to enable ultrathin,flexible,and high-brightness illumination devices.However,addressing the limitation of locally scattered small plasmon-enhanced areas remains challenging.Here,we present a 2D plasmonic enhancement of photoluminescence(PL)spanning nearly 800μm^(2),enabled by surface lattice resonance(SLR)in a 2D vdWM-Au slot lattice hybrid.The Au slot lattice is designed and fabricated using Babinet’s principle and Rayleigh’s anomaly to maximize radiative decay rate and induce non-local photo-excitation in a MoSe_(2)monolayer.For emitted PL coupled with SLR,enhanced by up to 32-fold,we investigate its in-plane directivity and long-range propagation using angle-and space-resolved spectroscopic PL measurements.Our experiment reveals that a nearly 800μm^(2)2D luminescent sheet can be achieved regardless of the size of the MoSe_(2)crystal,even with a sub-μm^(2)flake.This work provides a new type of ultrabright,large-area 2D luminescent material,suitable for a range of optical illumination,communication,and sensing devices.
基金supported by the National Natural Science Foundation of China(No.11304184)the Shandong University of Technology and Zibo City Integration Development Project(No.2019ZBXC120)。
文摘Based on the nonlinear saturable absorption properties(NSAPs)of a two-dimensional(2D)material of antimony selenide(Sb_(2)Se_(3)),a Q-switched erbium-doped fiber(EDF)laser is systematically demonstrated.The Sb_(2)Se_(3)nano sheets are prepared by liquid-phase exfoliation(LPE)method.After the sandwich-structured Sb_(2)Se_(3)saturable absorber(SA)is fabricated,the NSAPs are characterized and the modulation depth,the saturation intensity and the unsaturated loss are determined to be 25.2%,2.02 MW/cm^(2),and 3.29%,respectively.When the as-prepared Sb_(2)Se_(3)-SA is integrated into the ring cavity,the laser operates at a stable Q-switching regime in the pump power range of 100—400 mW.The laser oscillates at the central wavelength of 1558.48 nm with a 3 dB bandwidth of 2.32 nm.Take the advantages of the Sb_(2)Se_(3)-SA,the pulse duration can be compressed from 40.49 kHz to 128.12 kHz.At the pump power of 400 mW,the Q-switching laser gives the narrowest pulse duration the highest average output power,the largest pulse energy,and the signal-to-noise ratio(SNR)of 0.93μs,2.16 mW,16.89 nJ,and 53 dB,respectively.Our new attempt on Sb_(2)Se_(3)-based Q-switched EDF laser,combining the existing mode-locking achievements,proves that Sb_(2)Se_(3)is a powerful candidate for pulse compression due to the characteristics of high modulation depth and high stability.
基金the support from an Empa interal research grant.
文摘Rechargeable lithium-sulfur(Li-S)batteries have attracted significant research attention due to their high capacity and energy density.However,their commercial applications are still hindered by challenges such as the shuttle effect of soluble lithium sulfide species,the insulating nature of sulfur,and the fast capacity decay of the electrodes.Various efforts are devoted to address these problems through questing more conductive hosts with abundant polysulfide chemisorption sites,as well as modifying the separators to physically/chemically retard the polysulfides migration.Two dimensional transition metal carbides,carbonitrides and nitrides,so-called MXenes,are ideal for confining the polysulfides shuttling effects due to their high conductivity,layered structure as well as rich surface terminations.As such,MXenes have thus been widely studied in Li-S batteries,focusing on the conductive sulfur hosts,polysulfides interfaces,and separators.Therefore,in this review,we summarize the significant progresses regarding the design of multifunctional MXene-based Li-S batteries and discuss the solutions for improving electrochemical performances in detail.In addition,challenges and perspectives of MXenes for Li-S batteries are also outlined.
基金supported by the National Natural Science Foundation of China(No.61575059,No.61675062,No.21501038)the Fundamental Research Funds for the Central Universities(No.JZ2018HGPB0275,No.JZ2018HGTA0220,and No.JZ2018HGXC0001).
文摘In this study,we have developed a high-sensitivity,near-infrared photodetector based on PdSe2/GaAs heterojunction,which was made by transferring a multilayered PdSe2 film onto a planar GaAs.The as-fabricated PdSe2/GaAs heterojunction device exhibited obvious photovoltaic behavior to 808 nm illumination,indicating that the near-infrared photodetector can be used as a self-driven device without external power supply.Further device analysis showed that the hybrid heterojunction exhibited a high on/off ratio of 1.16×10^5 measured at 808 nm under zero bias voltage.The responsivity and specific detectivity of photodetector were estimated to be 171.34 mA/W and 2.36×10^11 Jones,respectively.Moreover,the device showed excellent stability and reliable repeatability.After 2 months,the photoelectric characteristics of the near-infrared photodetector hardly degrade in air,attributable to the good stability of the PdSe2.Finally,the PdSe2/GaAs-based heterojunction device can also function as a near-infrared light sensor.
基金supported by National University of Singapore No. CENGas R-261-508-001-646)Ministry of Education – Singapore ( 13No. MOE Ac RF Tier 1 R-279-000-472-112)
文摘Two-dimensional（2 D） materials have attracted increasing attentions recently due to their unique physical and chemical properties. We herein report the synthesis of four chemically stable 2 D covalent organic nanosheets（CONs） with large lateral sizes（up to 200 mm） and high aspect ratios（〉20 000） at the air-water interface through the Langmuir-Blodgett method. These CONs exhibit good crystallinity proved by high resolution transmission electron microscopy（HRTEM） and selected area electron diffraction（SAED）. In addition, the hydrophobicity of these CONs can be systematically adjusted by the introduction of various functional groups, making them suitable as functional coating and membrane materials.
基金the National Natural Science Foundation of China(Nos.21872169,91845109,21688102,and 21825203)the National Key R&D Program of China(No.2016YFA0200200)+2 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB17020000)China Postdoctoral Science Foundation(No.2019M651997)Natural Science Foundation of Jiangsu Province(No.BK20200257).
文摘The synthesis of high-quality ultrathin overlayers is critically dependent on the surface structure of substrates,especially involving the overlayer–substrate interaction.By using in situ surface measurements,we demonstrate that the overlayer–substrate interaction can be tuned by doping near-surface Ar nanobubbles.The interfacial coupling strength significantly decreases with near-surface Ar nanobubbles,accompanying by an“anisotropic to isotropic”growth transformation.On the substrate containing near-surface Ar,the growth front crosses entire surface atomic steps in both uphill and downhill directions with no difference,and thus,the morphology of the two-dimensional(2D)overlayer exhibits a round-shape.Especially,the round-shaped 2D overlayers coalesce seamlessly with a growth acceleration in the approaching direction,which is barely observed in the synthesis of 2D materials.This can be attributed to the immigration lifetime and diffusion rate of growth species,which depends on the overlayer–substrate interaction and the surface catalysis.Furthermore,the“round to hexagon”morphological transition is achieved by etching-regrowth,revealing the inherent growth kinetics under quasi-freestanding conditions.These findings provide a novel promising way to modulate the growth,coalescence,and etching dynamics of 2D materials on solid surfaces by adjusting the strength of overlayer–substrate interaction,which contributes to optimization of large-scale production of 2D material crystals.
基金The project was supported by Equipment Pre-research Key Laboratory Fund(No.6142020305)The authors would like to thank Shiyanjia Lab(www.shiyanjia.com)for the support of XPS test.
文摘Hexagonal boron nitride nanosheets(HBNNSs)have huge potential in the field of coating materials owing to their remarkable chemical stability,mechanical strength and thermal conductivity.Thin-layer hBNNSs were obtained by a liquid-phase exfoliation of h-BN powders and incorporated into EVA coatings for improving the safety performance of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).HBNNSs and ethylene-vinyl acetate copolymer(EVA)were introduced to HMX by a solvent-slurry process.For comparison,the HMX/EVA and HMX/EVA/graphene(HMX/EVA/G)composites were also prepared by a similar process.The morphology,crystal form,surface element distribution,thermal decomposition property and impact sensitivity of HMX/EVA/hBNNSs composites were contrastively investigated.Results showed that as prepared HMX/EVA/hBNNSs composites were well coated with hBNNSs and EVA,and exhibited better thermal stability and lower impact sensitivity than that of HMX/EVA and HMX/EVA/G composites,suggesting superior performance of desensitization of hBNNSs in explosives.
文摘Graphdiyne(GDY),a rising star of carbon allotrope with sp-/sp?.hybridized one-atom-thick all-carbon two-dimensional(2D)network,has shown numerous unique structure and fascinating properties.Since the first successful synthesis of GDY in 2010,GDY research has made a series of great progresses,and promoted the fundamental researches and practical applications in various fields of chemistry,physics,information science,material science,life science and environmental science and so on.
文摘Due to their reduced dimensionality and strong quantumconfinement, two-dimensional (2D) materials have emerged as aversatile platform for exploring quantum phenomena absent intheir bulk counterparts. Stacking 2D materials to form bilayerheterostructures or homostructures introduces additionaldegrees of freedom to tune or even create novel quantumproperties [1]. A prominent example is the discovery of flatbands and superconductivity in twisted bilayer graphene at asmall “magic” twist angle, where suppressed electron kineticsamplifies electron correlation, giving rise to emergent quantumphenomena [2]. Another notable case is the formation of quasicrystalsin bilayer graphene at the large twist angle, whichfurther expands the possibilities for tailoring electronic structures[3].
基金supported by the National Basic Research Program of China (2017YFA0206702)the National Natural Science Foundation of China (21925110, 21890751, 91745113)+6 种基金the China Postdoctoral Science Foundation (2019TQ0299)the Fundamental Research Funds for the Central Universities (WK 2060190084)the Natural Science Foundation of China (U1832168)the Anhui Provincial Natural Science Foundation (1808085MB26)the Fundamental Research Funds for the Central Universities (WK5290000001)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB36000000)China National Postdoctoral Program for Innovative Talents (BX2021283)。
文摘Exploring new strategies to broaden the upper/lower limit of thermal conductivity is of great interest to develop thermal management materials that can adapt to extreme environments.In this work,we employ an interfacial ion regulation to enhance the thermal insulation performance of 2D layered double hydroxide nanosheets.The introduction of interfacial ion enlarges the interplanar spacing of Co(OH)_(2) nanosheets from 4.64 to 8.05 ?,which reduces phonon scattering length perpendicular to the two-dimensional plane and leads to enhanced interlayer thermal insulation.The interfacial ion-regulated Co(OH)_(2)(named as Co(OH)_(2)-M^(x-)) exhibits 3-fold enhancement of thermal insulation through decreasing the thermal conductivity to as low as 0.15 W m^(-1) K^(-1),which is among the top values in 2D solid materials.We anticipate that interfacial ion regulation for 2D nanosheets paves a new avenue to break through the thermal insulation limit.
基金Ministry of Education—Singapore,Grant/Award Number:MOE2018‐T3‐1‐005。
文摘Two‐dimensional transition metal dichalcogenides(TMDs)play host to a wide range of novel topological states,such as quantum spin Hall insulators,superconductors,and Weyl semimetals.The rich polymorphism in TMDs suggests that phase engineering can be used to switch between different charge order states.Intercalation of atoms or molecules into the van der Waals gap of TMDs has emerged as a powerful approach to modify the properties of the material,leading to phase transition or the formation of substoichiometric phases via compositional tuning,thus broadening the electronic and optical landscape of these materials for a wide range of applications.Here,we review the current efforts in the preparation of intercalated TMD.The challenges and opportunities for intercalated TMDs to create a new device paradigm for material science are discussed.
基金This work was supported by the National Natural Science Foundation of China(51702203,51772182,21471093)the Program for Key Science&Technology Innovation Team of Shaanxi Province(2012KCT-21),the 111 Project(B14041)the Fundamental Research Funds for the Central Universities(GK201501007).
文摘Black phosphorus(BP),especially for BP nanosheets,with unique layered structure among two dimensional(2D)materials has attracted much attention due to its outstanding physical properties,such as ultra-high mobility,in-plane anisotropic properties.However,the small horizontal-size of reported BP limits its applications in the integrated circuit or some functional devices.In this work,a solvothermalassisted liquid-phase exfoliation technique is firstly employed for preparing large size and high-quality BP nanosheets.In the high-polar acetonitrile solvent,solvothermal treatment weakens the Van der Waals forces of block BP.Together with the subsequently ultrasonic processing,effective exfoliation of large size and high-quality BP nanosheets are realized.The TEM,AFM and Raman results indicate that the prepared BP nanosheets are high quality with an average thickness of about 2 nm,and the horizontalsize is up to 10μm.This facile and effective method for exfoliated BP nanosheets provides a promising strategy for the exfoliation of other 2D materials.
基金The authors would like to thank Georgios Katsaros and Tim Wehling for valuable discussions. Stephan Br~iuer, Albin Schwarz, and Ursula Kainz are ackno- wledged for technical support. A. M. acknowledges the financial support through BES-2013-062593. G. G. acknowledges support from the Austrian Science Fund through project P 28018-B27. I. Z. acknowledges financial support from the Swiss National Science Foundation research grant （No. 200021_165784）. This work was partially funded by the Austrian Science Fund through the projects P24471 and P26830, and by the Spanish Ministry for Economy and Competitiveness trough the project MINECO/FEDER TEC2015-69916- C2-1-R.
文摘Two-dimensional transition metal dichalcogenide semiconductors have emerged as promising candidates for optoelectronic devices with unprecedented properties and ultra-compact footprints. However, the high sensitivity of atomically thin materials to the surrounding dielectric media imposes severe limitations on their practical applicability. Hence, to enable the effective integration of these materials in devices, the development of reliable encapsulation procedures that preserve their physical properties is required. Here, the excitonic photoluminescence （at room temperature and 10 K） is assessed on mechanically exfoliated WSe2 monolayer flakes encapsulated with SiOx and AlxOy layers by means of chemical and physical deposition techniques. Conformal coating on untreated and non- functionalized flakes is successfully achieved by all the techniques examined, with the exception of atomic layer deposition, for which a cluster-like oxide coating is formed. No significant compositional or strain state changes in the flakes are detected upon encapsulation, independently of the technique adopted. Remarkably, our results show that the optical emission of the flakes is strongly influenced by the stoichiometry quality of the encapsulating oxide. When the encapsulation is carried out with slightly sub-stoichiometric oxides, two remarkable phenomena are observed. First, dominant trion （charged exciton） photoluminescence is detected at room temperature, revealing a clear electrical doping of the monolayers. Second, a strong decrease in the optical emission of the monolayers is observed, and attributed to non-radiative recombination processes and/or carrier transfer from the flake to the oxide. Power- and temperature-dependent photoluminescence measurements further confirm that stoichiometric oxides obtained by physical deposition lead to a successful encapsulation, opening a promising route for the development of integrated two-dimensional devices.
