Transition metal oxides hold great promise for lithium-ion batteries(LIBs)and electrocatalytic water splitting because of their high abundance and high energy density.However,designing and fabrication of efficient,sta...Transition metal oxides hold great promise for lithium-ion batteries(LIBs)and electrocatalytic water splitting because of their high abundance and high energy density.However,designing and fabrication of efficient,stable,high power density electrode materials are challenging.Herein,we report rambutan-like hollow carbon spheres formed by carbon nanosheet decorated with nickel oxide(NiO)rich inmetal vacancies(denoted as h-NiO/C)as a bifunctional electrode material for LIBs and electrocatalytic oxygen evolution reaction(OER).When being used as the anode of LIBs,the h-NiO/C electrode shows a large initial capacity of 885mAh g−1,a robust stability with a high capacity of 817mAh g−1 after 400 cycles,and great rate capability with a high reversible capacity of 523mAh g−1 at 10Ag−1 after 600 cycles.Moreover,working as an OER electrocatalyst,the h-NiO/C electrode shows a small overpotential of 260mV at 10mAcm−2,a Tafel slope of 37.6mVdec−1 along with good stability.Our work offers a cost-effective method for the fabrication of efficient electrode for LIBs and OER.展开更多
Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and str...Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and strong evanescent field. All these properties of WGM microresonators have ensured their great potentials for applications, such as physical sen- sors, bio/chemical sensors and microlasers. In this mini-review, the key parameters and coupling conditions of WGM microresonators are firstly introduced. The geometries of WGM optical microcavities are presented based on their fabri- cation methods. This is followed by the discussion on the state-of-the-art applications of WGM microresonators in sen- sors and microlasers.展开更多
Understanding the relationship between CO_(2) reduction reaction(CO_(2)RR)performance and surface terminations of MXenes is crucial for designing effective electrocatalysts.This study explores the impact of common ter...Understanding the relationship between CO_(2) reduction reaction(CO_(2)RR)performance and surface terminations of MXenes is crucial for designing effective electrocatalysts.This study explores the impact of common terminations on Mo_(2)CT_(x) using a computational hydrogen electrode(CHE)model integrated with a pseudo-microkinetic model(pseudo-MM).Unlike traditional CHE methods,CHE/pseudo-MM considers the energy differences of all steps,providing a comprehensive view of CO_(2)RR mechanisms while reducing computational cost generated from calculating transitional state.The electrolyte is considered as acetonitrile with 1-ethyl-3-methylimidazolium tetra-fluoroborate(EMIMBF_(4))to inhibit the generation of hydrogen.Theoretical predictions reveal surface terminations dictate the selectivity of C_(1) products,whose proton is provided by EMIMBF_(4).The selectivity for fully-F,-O-and-OH-terminated Mo_(2)CT_(x) surfaces varies with the applied potential,as confirmed by experiments.Electrochemical CO_(2)RR in acetonitrile with EMIMBF_(4) electrolyte confirms these predictions,showing that CH_(4) outperforms CO and gradually becomes the dominant product as the applied potential increases.These findings demonstrate the qualitative accuracy of the proposed CHE/pseudo-MM for predicting CO_(2)RR selectivity,particularly for gaseous products,over Mo_(2)CT_(x) systems.展开更多
Elastic and stretchable functional fibers have drawn attentions from wide research field because of their unique advantages including high dynamic bending elasticity,stretchability and high mechanic strength.Lots of e...Elastic and stretchable functional fibers have drawn attentions from wide research field because of their unique advantages including high dynamic bending elasticity,stretchability and high mechanic strength.Lots of efforts have been made to find promising soft materials and improve the processing methods to fabricate the elastomer fibers with controllable fiber geometries and designable functionalities.Significant progress has been made and various interdisciplinary applications have been demonstrated based on their unique mechanical performance.A series of remarkable applications,involving biomedicine,optics,electronics,human machine interfaces etc.,have been successfully achieved.Here,we summarize main processing methods to fabricate soft and stretchable functional fibers using different types of elastic materials,which are either widely used or specifically developed.We also introduce some representative applications of multifunctional elastic fibers to reveal this promising research area.All these reported applications indicate that the fast innovated interdisciplinary area is of great potential and inspire more remarkable ideas in fiber sensing,soft electronics,functional fiber integration and other related research fields.展开更多
The evolution of soliton molecules emphasizes the complex soliton dynamics akin to matter molecules.Beyond the simplest soliton molecule-a soliton pair constituted by two bound pulses-soliton molecules with more const...The evolution of soliton molecules emphasizes the complex soliton dynamics akin to matter molecules.Beyond the simplest soliton molecule-a soliton pair constituted by two bound pulses-soliton molecules with more constituents have more degrees of freedom because of the temporal pulse separations and relative phases.Here we detailedly characterize the transient dynamics of soliton triplets in fiber lasers by using the dispersive Fourier transform measurement.A particular form of leading,central,and tailing pulses is constructed to shed new light on more intriguing scenarios and fuel the molecular analogy.Especially the vibrating dynamics of the central and tailing pulses are captured near the regime of equally spaced soliton triplets,which is reminiscent of the recurrent timing jitters within multi-pulse structures.Further insights enable acess into a universal form of unequally spaced soliton triplets interpreted as 2+1 soliton molecules.Different binding strengths of intramo-lecular and intermolecular bonds are validated with respect to the diverse internal motions involved in this soliton triplet molcule.All these findings unveil the transient dynamics with more degrees of freedom as well as highlight the possible application for all-optical bit storage.展开更多
Our theoretical findings demonstrate for the first time a possibility of band-gap engineering of monolayer MoS2 crystals by oxygen and the presence of vacancies. Oxygen atoms are revealed to substitute sulfur ones, fo...Our theoretical findings demonstrate for the first time a possibility of band-gap engineering of monolayer MoS2 crystals by oxygen and the presence of vacancies. Oxygen atoms are revealed to substitute sulfur ones, forming stable MoS2-xOx ternary compounds, or adsorb on top of the sulfur atoms. The substituting oxygen provides a decrease of the band gap from 1.86 to 1.64 eV and transforms the material from a direct-gap to an indirect-gap semiconductor. The surface adsorbed oxygen atoms decrease the band gap up to 0.98 eV depending on their location tending to the metallic character of the electron energy bands at a high concentration of the adsorbed atoms. Oxygen plasma processing is proposed as an effective technology for such band-gap modifications.展开更多
Optical barcodes have demonstrated a great potential in multiplexed bioassays and cell tracking for their distinctive spectral fingerprints.The vast majority of optical barcodes were designed to identify a specific ta...Optical barcodes have demonstrated a great potential in multiplexed bioassays and cell tracking for their distinctive spectral fingerprints.The vast majority of optical barcodes were designed to identify a specific target by fluorescence emission spectra,without being able to characterize dynamic changes in response to analytes through time.To overcome these limitations,the concept of the bioresponsive dynamic photonic barcode was proposed by exploiting interfacial energy transfer between a microdroplet cavity and binding molecules.Whispering-gallery modes resulting from cavity-enhanced energy transfer were therefore converted into photonic barcodes to identify binding activities,in which more than trillions of distinctive barcodes could be generated by a single droplet.Dynamic spectral barcoding was achieved by a significant improvement in terms of signal-to-noise ratio upon binding to target molecules.Theoretical studies and experiments were conducted to elucidate the effect of different cavity sizes and analyte concentrations.Timeresolved fluorescence lifetime was implemented to investigate the role of radiative and non-radiative energy transfer.Finally,microdroplet photonic barcodes were employed in biodetection to exhibit great potential in fulfilling biomedical applications.展开更多
In recent years,two-dimensional(2D)ternary materials have attracted wide attention due to their novel properties which can be achieved by regulating their chemical composition with a very great degree of freedom and a...In recent years,two-dimensional(2D)ternary materials have attracted wide attention due to their novel properties which can be achieved by regulating their chemical composition with a very great degree of freedom and adjustable space.However,as for the precise synthesis of 2D ternary materials,great challenges still lie ahead that hinder their further development.In this work,we demonstrated a simple and reliable approach to synthesize 2D ternary-layered BiOCl crystals through a microwave-assisted space-confined process in a short time(<3 minutes).Their ultraviolet(UV)detection performance was analyzed systematically.The photodetectors based on the as-obtained BiOCl platelets demonstrate high sensitivity to 266-nm laser illumination.The responsivity is calculated to be8 A/W and the response time is up to be18 ps.On the other hand,the device is quite stable after being exposed in the ambient air within 3 weeks and the response is almost unchanged during the measurement.The facile and fast synthesis of single crystalline BiOCl platelets and its high sensitivity to UV light irradiation indicate the potential optoelectronic applications of 2D BiOCl photodetectors.展开更多
Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom...Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom, including real spin, valley pseudospin, and layer pseudospin. For example, spin-valley coupling results in valley-dependent circular dichroism in which electrons with particular spin （up or down） can be selectively excited by chiral optical pumping in monolayer TMDs, whereas in few-layer TMDs, the interlayer hopping further affects the spin-valley coupling. In addition to valley and layer pseudospins, here we propose a new degree of freedom--stacking pseudospin--and demonstrate new phenomena correlated to this new stacking freedom that otherwise require the application of external electrical or magnetic field. We investigated all possible stacking configurations of chemical-vapor-deposition-grown trilayer MoS2 （AAA, ABB, AAB, ABA, and 3R）. Although the AAA, ABA, 3R stackings possess a sole peak with lower degree of valley polarization than that in monolayer samples, the AAB （ABB） stackings exhibit two distinct peaks, one similar to that observed in monolayer MoS2 and findings provide a more future valleytronics. an additional unpolarized complete understanding of peak at lower energy. Our valley quantum control for展开更多
The Sabatier principle—which states that the best catalyst should be at the peak of the volcano plot,with neither too strong nor too weak intermediate binding strength—plays the golden rule in designing highly activ...The Sabatier principle—which states that the best catalyst should be at the peak of the volcano plot,with neither too strong nor too weak intermediate binding strength—plays the golden rule in designing highly active electrocatalysts.For instance,Pt with a“just right”hydrogen adsorption free energy(ΔG_(H^(*))=~0 eV)is the most efficient catalyst for hydrogen evolution reaction(HER).^(1)Nevertheless,the pressing demand for renewable energy has sparked a quest beyond the top of the volcano plot,driving the innovation towards more effective,economical.展开更多
The continuous downscaling(sub 5-nm nodes) of the processing technology is severely hampered by the shortchannel effects of the silicon(Si) material, which degrade the transistor's performance and raise the demand...The continuous downscaling(sub 5-nm nodes) of the processing technology is severely hampered by the shortchannel effects of the silicon(Si) material, which degrade the transistor's performance and raise the demand in the development of new device structures and materials to overcome them. Two-dimensional(2D) semiconductors are promising candidates for next-generation electronic materials owing to their atomic thickness and van der Waals(vdW) surface.展开更多
Recent advances in engineered material technologies(e.g.,photonic crystals,metamaterials,plasmonics,etc.)provide valuable tools to control Cherenkov radiation.In all these approaches,however,the particle velocity is a...Recent advances in engineered material technologies(e.g.,photonic crystals,metamaterials,plasmonics,etc.)provide valuable tools to control Cherenkov radiation.In all these approaches,however,the particle velocity is a key parameter to affect Cherenkov radiation in the designed material,while the influence of the particle trajectory is generally negligible.Here,we report on surface Dyakonov-Cherenkov radiation,i.e.the emission of directional Dyakonov surface waves from a swift charged particle moving atop a birefringent crystal.This new type of Cherenkov radiation is highly susceptible to both the particle velocity and trajectory,e.g.we observe a sharp radiation enhancement when the particle trajectory falls in the vicinity of a particular direction.Moreover,close to the Cherenkov threshold,such a radiation enhancement can be orders of magnitude higher than that obtained in traditional Cherenkov detectors.These distinct properties allow us to determine simultaneously the magnitude and direction of particle velocities on a compact platform.The surface Dyakonov-Cherenkov radiation studied in this work not only adds a new degree of freedom for particle identification,but also provides an all-dielectric route to construct compact Cherenkov detectors with enhanced sensitivity.展开更多
Two-dimensional(2D)ferromagnets with out-of-plane(OOP)magnetic anisotropy are potential candidates for realizing the next-generation memory devices with ultra-low power consumption and high storage density.However,a s...Two-dimensional(2D)ferromagnets with out-of-plane(OOP)magnetic anisotropy are potential candidates for realizing the next-generation memory devices with ultra-low power consumption and high storage density.However,a scalable approach to synthesize 2D magnets with OOP anisotropy directly on the complimentary metal-oxide semiconductor(CMOS)compatible substrates has not yet been mainly explored,which hinders the practical application of 2D magnets.This work demonstrates a cascaded space confined chemical vapor deposition(CS-CVD)technique to synthesize 2D FexGeTe_(2) ferromagnets.The weight fraction of iron(Fe)in the precursor controls the phase purity of the as-grown FexGeTe2.As a result,high-quality Fe_(3)GeTe_(2) and Fe_(5)GeTe_(2) flakes have been grown selectively using the CS-CVD technique.Curie temperature(Tc)of the as-grown FexGeTe2 can be up to-280 K,nearly room temperature.The thickness and temperature-dependent magnetic studies on the Fe_(5)GeTe_(2) reveal a 2D Ising to 3D XY behavior.Also,Terahertz spectroscopy experiments on Fe_(5)GeTe_(2) display the highest conductivity among other FexGeTe_(2) 2D magnets.The results of this work indicate a scalable pathway for the direct growth and integration of 2D ternary magnets on CMOS-based substrates to develop spintronic memory devices.展开更多
Nonlinear optical activities,especially second harmonic generation(SHG),are key phenomena in inversion-symmetrybroken two-dimensional(2D)transition metal dichalcogenides(TMDCs).On the other hand,anisotropic nonlinear ...Nonlinear optical activities,especially second harmonic generation(SHG),are key phenomena in inversion-symmetrybroken two-dimensional(2D)transition metal dichalcogenides(TMDCs).On the other hand,anisotropic nonlinear optical processes are important for unique applications in nano-nonlinear photonic devices with polarization functions,having become one of focused research topics in the field of nonlinear photonics.However,the strong nonlinearity and strong optical anisotropy do not exist simultaneously in common 2D materials.Here,we demonstrate strong secondorder and third-order susceptibilities of 64 pm/V and 6.2×10^(-19)m^(2)/V^(2),respectively,in the even-layer PdPSe,which has not been discovered in other common TMDCs(e.g.,MoS2).Strikingly,it also simultaneously exhibited strong SHG anisotropy with an anisotropic ratio of~45,which is the largest reported among all 2D materials to date,to the best of our knowledge.In addition,the SHG anisotropy ratio can be harnessed from 0.12 to 45(375 times)by varying the excitation wavelength due to the dispersion ofχ^(2)values.As an illustrative example,we further demonstrate polarized SHG imaging for potential applications in crystal orientation identification and polarization-dependent spatial encoding.These findings in 2D PdPSe are promising for nonlinear nanophotonic and optoelectronic applications.展开更多
MoS_(2) nanomaterial with the micro-pompon structure was synthesized by a surfactant-assisted hydrothermal method.The morphologies and structures of as-prepared MoS_(2) micro-pompon were investigated by adding differe...MoS_(2) nanomaterial with the micro-pompon structure was synthesized by a surfactant-assisted hydrothermal method.The morphologies and structures of as-prepared MoS_(2) micro-pompon were investigated by adding different types of surfactants such as cetyltrimethyl ammonium bromide(CTAB),sodium dodecylbenzene sulphonate(SDBS),and polyvinyl pyrrolidone(PVP).The results indicated that the morphology of MoS_(2) could be controlled and changed effectively by the cationic sur-factant of CTAB.A reasonable growth mechanism for hollow structured MoS_(2) micro-pompon by hydrothermal processes was proposed.Further,photocatalytic degradation properties of MoS_(2) micro-pompon under visible light were evaluated by degradation of common organic dyes,which include rhodamine B(RhB),congo red,methyl orange,and methylene blue.The results indicated that MoS_(2) micro-pompon owned the highly selective catalytic ability to RhB with degradation efficiency of 95%in 60 min and 68%in 30 min.With the additive of the surfactant,the MoS_(2)-CTAB sample exhibited an enhanced ability of photocatalytic activity where degradation efficiency was improved to 92%in 30 min.The method employed in this work could be expanded to fabricate other sulfides with the controllable morphology and structure to further regulate the photocatalytic performance.展开更多
Two-dimensional transition metal dichalcogenides(2D TMDs)are promising as sensing materials for flexible electronics and wearable systems in artificial intelligence,tele-medicine,and internet of things(IoT).Currently,...Two-dimensional transition metal dichalcogenides(2D TMDs)are promising as sensing materials for flexible electronics and wearable systems in artificial intelligence,tele-medicine,and internet of things(IoT).Currently,the study of 2D TMDs-based flexible strain sensors mainly focuses on improving the performance of sensitivity,response,detection resolution,cyclic stability,and so on.There are few reports on power consumption despite that it is of significant importance for wearable electronic systems.It is still challenging to effectively reduce the power consumption for prolonging the endurance of electronic systems.Herein,we propose a novel approach to realize ultra-low power consumption strain sensors by reducing the contact resistance between metal electrodes and 2D MoS_(2).A dendritic bilayer MoS_(2) has been designed and synthesized by a modified CVD method.Large-area edge contact has been introduced in the dendritic MoS_(2),resulting in decreased the contact resistance significantly.The contact resistance can be down to 5.4 kΩμm,which is two orders of magnitude lower than the conventional MoS_(2) devices.We fabricate a flexible strain sensor,exhibiting superior sensitivity in detecting strains with high resolution(0.04%)and an ultra-low power consumption(33.0 pW).This study paves the way for future wearable and flexible sensing electronics with high sensitivity and ultra-low power consumption.展开更多
Excitonics,an alternative to romising for processing information since semiconductor electronics is rapidly approaching the end of Moore’s law.Currently,the development of excitonic devices,where exciton flow is cont...Excitonics,an alternative to romising for processing information since semiconductor electronics is rapidly approaching the end of Moore’s law.Currently,the development of excitonic devices,where exciton flow is controlled,is mainly focused on electric-field modulation or exciton polaritons in high-Q cavities.Here,we show an alloptical strategy to manipulate the exciton flow in a binary colloidal quantum well complex through mediation of the Förster resonance energy transfer(FRET)by stimulated emission.In the spontaneous emission regime,FRET naturally occurs between a donor and an acceptor.In contrast,upon stronger excitation,the ultrafast consumption of excitons by stimulated emission effectively engineers the excitonic flow from the donors to the acceptors.Specifically,the acceptors’stimulated emission significantly accelerates the exciton flow,while the donors’stimulated emission almost stops this process.On this basis,a FRET-coupled rate equation model is derived to understand the controllable exciton flow using the density of the excited donors and the unexcited acceptors.The results will provide an effective alloptical route for realizing excitonic devices under room temperature operation.展开更多
基金We acknowledge Dr Hangjun Ying from Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences for TEM characterizations.This study was supported by Nanyang Technological University under NAP award(M408050000)Singapore Ministry of Education Tier 1 program(2018-T1-001-051).We acknowledge Dr Hangjun Ying from Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences for TEM characterizations.This study was supported by Nanyang Technological University under NAP award(M408050000Singapore Ministry of Education Tier 1 program(2018-T1-001-051).
文摘Transition metal oxides hold great promise for lithium-ion batteries(LIBs)and electrocatalytic water splitting because of their high abundance and high energy density.However,designing and fabrication of efficient,stable,high power density electrode materials are challenging.Herein,we report rambutan-like hollow carbon spheres formed by carbon nanosheet decorated with nickel oxide(NiO)rich inmetal vacancies(denoted as h-NiO/C)as a bifunctional electrode material for LIBs and electrocatalytic oxygen evolution reaction(OER).When being used as the anode of LIBs,the h-NiO/C electrode shows a large initial capacity of 885mAh g−1,a robust stability with a high capacity of 817mAh g−1 after 400 cycles,and great rate capability with a high reversible capacity of 523mAh g−1 at 10Ag−1 after 600 cycles.Moreover,working as an OER electrocatalyst,the h-NiO/C electrode shows a small overpotential of 260mV at 10mAcm−2,a Tafel slope of 37.6mVdec−1 along with good stability.Our work offers a cost-effective method for the fabrication of efficient electrode for LIBs and OER.
基金This work is partially supported by National Natural Science Foundation of China （11774102）, the Scientific Research Funds and Promotion Program for Young and Middle-aged Teacher in Science ＆ Technology Research of Huaqiao University （ZQN-YXS04, 17BS412）, Open Fund of IPOC （BUPT）, National Research Foundation Singapore （NRF） （NRF-CRP13-2014-05）, European Union＇s Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement （No. 798916） and Singapore Ministry of Education Academic Research Fund Tier 1 （RG89/16）.
文摘Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and strong evanescent field. All these properties of WGM microresonators have ensured their great potentials for applications, such as physical sen- sors, bio/chemical sensors and microlasers. In this mini-review, the key parameters and coupling conditions of WGM microresonators are firstly introduced. The geometries of WGM optical microcavities are presented based on their fabri- cation methods. This is followed by the discussion on the state-of-the-art applications of WGM microresonators in sen- sors and microlasers.
基金support from Ministry of Education(MOE),Singapore(MOE2022-T1-RG8/22)support from the Singapore Ministry of Education AcRF Tier 2(MOE-MOET2EP10121-0006)and COE seed grant.
文摘Understanding the relationship between CO_(2) reduction reaction(CO_(2)RR)performance and surface terminations of MXenes is crucial for designing effective electrocatalysts.This study explores the impact of common terminations on Mo_(2)CT_(x) using a computational hydrogen electrode(CHE)model integrated with a pseudo-microkinetic model(pseudo-MM).Unlike traditional CHE methods,CHE/pseudo-MM considers the energy differences of all steps,providing a comprehensive view of CO_(2)RR mechanisms while reducing computational cost generated from calculating transitional state.The electrolyte is considered as acetonitrile with 1-ethyl-3-methylimidazolium tetra-fluoroborate(EMIMBF_(4))to inhibit the generation of hydrogen.Theoretical predictions reveal surface terminations dictate the selectivity of C_(1) products,whose proton is provided by EMIMBF_(4).The selectivity for fully-F,-O-and-OH-terminated Mo_(2)CT_(x) surfaces varies with the applied potential,as confirmed by experiments.Electrochemical CO_(2)RR in acetonitrile with EMIMBF_(4) electrolyte confirms these predictions,showing that CH_(4) outperforms CO and gradually becomes the dominant product as the applied potential increases.These findings demonstrate the qualitative accuracy of the proposed CHE/pseudo-MM for predicting CO_(2)RR selectivity,particularly for gaseous products,over Mo_(2)CT_(x) systems.
基金supported by the Singapore Ministry of Education Academic Research Fund Tier 2(MOE2019-T2-2-127 and T2EP50120-0005)A*STAR under AME IRG(A2083c0062)+2 种基金the Singapore Ministry of Education Academic Research Fund Tier 1(RG90/19 and RG73/19)the Singapore National Research Foundation Competitive Research Program(NRF-CRP18-2017-02)supported by Nanyang Technological University.
文摘Elastic and stretchable functional fibers have drawn attentions from wide research field because of their unique advantages including high dynamic bending elasticity,stretchability and high mechanic strength.Lots of efforts have been made to find promising soft materials and improve the processing methods to fabricate the elastomer fibers with controllable fiber geometries and designable functionalities.Significant progress has been made and various interdisciplinary applications have been demonstrated based on their unique mechanical performance.A series of remarkable applications,involving biomedicine,optics,electronics,human machine interfaces etc.,have been successfully achieved.Here,we summarize main processing methods to fabricate soft and stretchable functional fibers using different types of elastic materials,which are either widely used or specifically developed.We also introduce some representative applications of multifunctional elastic fibers to reveal this promising research area.All these reported applications indicate that the fast innovated interdisciplinary area is of great potential and inspire more remarkable ideas in fiber sensing,soft electronics,functional fiber integration and other related research fields.
基金National Natural Science Foundation of China(61775067,61775072)Ministry of Education-Singapore(MOE2019-T1-001-111)National Research Foundation Singapore(NRF-CRP-18-2017-02).
文摘The evolution of soliton molecules emphasizes the complex soliton dynamics akin to matter molecules.Beyond the simplest soliton molecule-a soliton pair constituted by two bound pulses-soliton molecules with more constituents have more degrees of freedom because of the temporal pulse separations and relative phases.Here we detailedly characterize the transient dynamics of soliton triplets in fiber lasers by using the dispersive Fourier transform measurement.A particular form of leading,central,and tailing pulses is constructed to shed new light on more intriguing scenarios and fuel the molecular analogy.Especially the vibrating dynamics of the central and tailing pulses are captured near the regime of equally spaced soliton triplets,which is reminiscent of the recurrent timing jitters within multi-pulse structures.Further insights enable acess into a universal form of unequally spaced soliton triplets interpreted as 2+1 soliton molecules.Different binding strengths of intramo-lecular and intermolecular bonds are validated with respect to the diverse internal motions involved in this soliton triplet molcule.All these findings unveil the transient dynamics with more degrees of freedom as well as highlight the possible application for all-optical bit storage.
基金supported by the Joint BRFFR-CNRS Project (No. F15F-003)the Visby Program: scholarships for PhD studies and postdoctoral research in Sweden
文摘Our theoretical findings demonstrate for the first time a possibility of band-gap engineering of monolayer MoS2 crystals by oxygen and the presence of vacancies. Oxygen atoms are revealed to substitute sulfur ones, forming stable MoS2-xOx ternary compounds, or adsorb on top of the sulfur atoms. The substituting oxygen provides a decrease of the band gap from 1.86 to 1.64 eV and transforms the material from a direct-gap to an indirect-gap semiconductor. The surface adsorbed oxygen atoms decrease the band gap up to 0.98 eV depending on their location tending to the metallic character of the electron energy bands at a high concentration of the adsorbed atoms. Oxygen plasma processing is proposed as an effective technology for such band-gap modifications.
基金We would like to thank the Centre of Bio-Devices and Bioinformatics and CNRS International—Nanyang Technological University-Thales Research Alliance(CINTRA)for lab supportWe would also like to thank NTU for the startup grant(SUG-M4082308.040).
文摘Optical barcodes have demonstrated a great potential in multiplexed bioassays and cell tracking for their distinctive spectral fingerprints.The vast majority of optical barcodes were designed to identify a specific target by fluorescence emission spectra,without being able to characterize dynamic changes in response to analytes through time.To overcome these limitations,the concept of the bioresponsive dynamic photonic barcode was proposed by exploiting interfacial energy transfer between a microdroplet cavity and binding molecules.Whispering-gallery modes resulting from cavity-enhanced energy transfer were therefore converted into photonic barcodes to identify binding activities,in which more than trillions of distinctive barcodes could be generated by a single droplet.Dynamic spectral barcoding was achieved by a significant improvement in terms of signal-to-noise ratio upon binding to target molecules.Theoretical studies and experiments were conducted to elucidate the effect of different cavity sizes and analyte concentrations.Timeresolved fluorescence lifetime was implemented to investigate the role of radiative and non-radiative energy transfer.Finally,microdroplet photonic barcodes were employed in biodetection to exhibit great potential in fulfilling biomedical applications.
基金National Research Foundation Singapore,Grant/Award Numbers:AStar QTE program.,AcRF Tier 2 MOE2017-T2-2-002,MOE Tier 2 MOE2015-T2-2-007,MOE Tier 3 MOE2018-T3-1-002,MOE2016-T2-2-153,MOE2017-T2-2-136,NRF-RF2013-08.MOE Tier 1 RG7/18,NRF2017-NRF-ANR0022DPSNatural Science Foundation of Jiangsu Province,Grant/Award Number:BK20160994+1 种基金This work was supported by the Singapore National Research Foundation under NRF RF Award No.NRF-RF2013-08.MOE Tier 1 RG7/18,MOE Tier 2 MOE2015-T2-2-007,MOE2016-T2-2-153,MOE2017-T2-2-136,MOE Tier 3 MOE2018-T3-1-002,AcRF Tier 2 MOE2017-T2-2-002,NRF2017-NRF-ANR0022DPS,and A*Star QTE program.Dan Tian thanks the National Nature Science Foundation of China(Grant No.21601086)the Natural Science Foundation of Jiangsu Province(BK20160994)for financial support.
文摘In recent years,two-dimensional(2D)ternary materials have attracted wide attention due to their novel properties which can be achieved by regulating their chemical composition with a very great degree of freedom and adjustable space.However,as for the precise synthesis of 2D ternary materials,great challenges still lie ahead that hinder their further development.In this work,we demonstrated a simple and reliable approach to synthesize 2D ternary-layered BiOCl crystals through a microwave-assisted space-confined process in a short time(<3 minutes).Their ultraviolet(UV)detection performance was analyzed systematically.The photodetectors based on the as-obtained BiOCl platelets demonstrate high sensitivity to 266-nm laser illumination.The responsivity is calculated to be8 A/W and the response time is up to be18 ps.On the other hand,the device is quite stable after being exposed in the ambient air within 3 weeks and the response is almost unchanged during the measurement.The facile and fast synthesis of single crystalline BiOCl platelets and its high sensitivity to UV light irradiation indicate the potential optoelectronic applications of 2D BiOCl photodetectors.
文摘Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom, including real spin, valley pseudospin, and layer pseudospin. For example, spin-valley coupling results in valley-dependent circular dichroism in which electrons with particular spin （up or down） can be selectively excited by chiral optical pumping in monolayer TMDs, whereas in few-layer TMDs, the interlayer hopping further affects the spin-valley coupling. In addition to valley and layer pseudospins, here we propose a new degree of freedom--stacking pseudospin--and demonstrate new phenomena correlated to this new stacking freedom that otherwise require the application of external electrical or magnetic field. We investigated all possible stacking configurations of chemical-vapor-deposition-grown trilayer MoS2 （AAA, ABB, AAB, ABA, and 3R）. Although the AAA, ABA, 3R stackings possess a sole peak with lower degree of valley polarization than that in monolayer samples, the AAB （ABB） stackings exhibit two distinct peaks, one similar to that observed in monolayer MoS2 and findings provide a more future valleytronics. an additional unpolarized complete understanding of peak at lower energy. Our valley quantum control for
基金Z.L.acknowledges funding from the Singapore Ministry of Education(AcRF MOE2019-362 T2-2-105 and AcRF Tier 1 RG7/21)Z.L.also acknowledges funding from the Ministry of Education,Singapore,under its Research Centre of Excellence award to the Institute for Functional Intelligent Materials(Project No.EDUNC-33-18-279-V12).
文摘The Sabatier principle—which states that the best catalyst should be at the peak of the volcano plot,with neither too strong nor too weak intermediate binding strength—plays the golden rule in designing highly active electrocatalysts.For instance,Pt with a“just right”hydrogen adsorption free energy(ΔG_(H^(*))=~0 eV)is the most efficient catalyst for hydrogen evolution reaction(HER).^(1)Nevertheless,the pressing demand for renewable energy has sparked a quest beyond the top of the volcano plot,driving the innovation towards more effective,economical.
文摘The continuous downscaling(sub 5-nm nodes) of the processing technology is severely hampered by the shortchannel effects of the silicon(Si) material, which degrade the transistor's performance and raise the demand in the development of new device structures and materials to overcome them. Two-dimensional(2D) semiconductors are promising candidates for next-generation electronic materials owing to their atomic thickness and van der Waals(vdW) surface.
基金Y.L.was sponsored in part by Singapore Ministry of Education(No.MOE2018-T2-2-189(S)),MOE2017-T1-001-239(RG91/17(S)),A*Star AME Programmatic Funds(No.A18A7b0058)and National Research Foundation Singapore Competitive Research Program(No.NRF-CRP18-2017-02)B.Z.was sponsored in part by Singapore Ministry of Education(No.MOE2018‐T2‐1‐022(S),MOE2016‐T3‐1‐006 and Tier 1 RG174/16(S))+3 种基金L.J.W.was sponsored in part by the Advanced Manufacturing and Engineering Young Individual Research Grant(No.A1984c0043)from the Science and Engineering Research Council of the Agency for Science,Technology and Research,SingaporeX.L.was sponsored in part by the National Natural Science Foundation of China(NSFC)(No.62175212)Fundamental Research Funds for the Central Universities(No.2021FZZX001-19)Zhejiang University Global Partnership Fund.
文摘Recent advances in engineered material technologies(e.g.,photonic crystals,metamaterials,plasmonics,etc.)provide valuable tools to control Cherenkov radiation.In all these approaches,however,the particle velocity is a key parameter to affect Cherenkov radiation in the designed material,while the influence of the particle trajectory is generally negligible.Here,we report on surface Dyakonov-Cherenkov radiation,i.e.the emission of directional Dyakonov surface waves from a swift charged particle moving atop a birefringent crystal.This new type of Cherenkov radiation is highly susceptible to both the particle velocity and trajectory,e.g.we observe a sharp radiation enhancement when the particle trajectory falls in the vicinity of a particular direction.Moreover,close to the Cherenkov threshold,such a radiation enhancement can be orders of magnitude higher than that obtained in traditional Cherenkov detectors.These distinct properties allow us to determine simultaneously the magnitude and direction of particle velocities on a compact platform.The surface Dyakonov-Cherenkov radiation studied in this work not only adds a new degree of freedom for particle identification,but also provides an all-dielectric route to construct compact Cherenkov detectors with enhanced sensitivity.
基金supported from National Research Foundation Singapore programme NRF-CRP22-2019-0007,NRF-CRP22-2019-0004 and NRF-CRP21-2018-0007supported by the Ministry of Education,Singapore,under its AcRF Tier 3 Programme‘Geometrical Quantum Materials’(MOE2018-T3-1-002),AcRF Tier 2(MOE2019-T2-2-105)and AcRF Tier 1 RG4/17 and RG7/18We also thank the funding support from National Research foundation(NRF-CRP22-2019-0004).
文摘Two-dimensional(2D)ferromagnets with out-of-plane(OOP)magnetic anisotropy are potential candidates for realizing the next-generation memory devices with ultra-low power consumption and high storage density.However,a scalable approach to synthesize 2D magnets with OOP anisotropy directly on the complimentary metal-oxide semiconductor(CMOS)compatible substrates has not yet been mainly explored,which hinders the practical application of 2D magnets.This work demonstrates a cascaded space confined chemical vapor deposition(CS-CVD)technique to synthesize 2D FexGeTe_(2) ferromagnets.The weight fraction of iron(Fe)in the precursor controls the phase purity of the as-grown FexGeTe2.As a result,high-quality Fe_(3)GeTe_(2) and Fe_(5)GeTe_(2) flakes have been grown selectively using the CS-CVD technique.Curie temperature(Tc)of the as-grown FexGeTe2 can be up to-280 K,nearly room temperature.The thickness and temperature-dependent magnetic studies on the Fe_(5)GeTe_(2) reveal a 2D Ising to 3D XY behavior.Also,Terahertz spectroscopy experiments on Fe_(5)GeTe_(2) display the highest conductivity among other FexGeTe_(2) 2D magnets.The results of this work indicate a scalable pathway for the direct growth and integration of 2D ternary magnets on CMOS-based substrates to develop spintronic memory devices.
基金supported by the Singapore Ministry of Education(MOET2EP50120-0009)Agency for Science,Technology and Research(A*STAR)(M22K2c0080,R23I0IR041,and A2090b0144)+3 种基金National Medical Research Council(NMRC)(Award number MOH-000927)National Research Foundation Singapore(Award No.NRF-CRP22-2019-0007 and NRF-CRP23-2019-0007)National Research Foundation,Singapore under its AI Singapore Programme(AISG Award No:AISG2-GC-2023-009)National Research Foundation(Award No.NRF2020-NRF-ISF004-3520).
文摘Nonlinear optical activities,especially second harmonic generation(SHG),are key phenomena in inversion-symmetrybroken two-dimensional(2D)transition metal dichalcogenides(TMDCs).On the other hand,anisotropic nonlinear optical processes are important for unique applications in nano-nonlinear photonic devices with polarization functions,having become one of focused research topics in the field of nonlinear photonics.However,the strong nonlinearity and strong optical anisotropy do not exist simultaneously in common 2D materials.Here,we demonstrate strong secondorder and third-order susceptibilities of 64 pm/V and 6.2×10^(-19)m^(2)/V^(2),respectively,in the even-layer PdPSe,which has not been discovered in other common TMDCs(e.g.,MoS2).Strikingly,it also simultaneously exhibited strong SHG anisotropy with an anisotropic ratio of~45,which is the largest reported among all 2D materials to date,to the best of our knowledge.In addition,the SHG anisotropy ratio can be harnessed from 0.12 to 45(375 times)by varying the excitation wavelength due to the dispersion ofχ^(2)values.As an illustrative example,we further demonstrate polarized SHG imaging for potential applications in crystal orientation identification and polarization-dependent spatial encoding.These findings in 2D PdPSe are promising for nonlinear nanophotonic and optoelectronic applications.
基金This work was financially supported by the National Research Foundation Singapore programme(Grant Nos.NRF-CRP21-2018-0007 and NRF-CRP22-2019-0007)Singapore Ministry of Education via AcRF Tier 3 Programme’Geometrical Quantum Materials’(Grant No.MOE2018-T3-1-002)+8 种基金AcRF Tier 2(Grant No.MOE2016-T2-1-131)AcRF Tier 1 RG4/17 and RG7/18,the National Natural Science Foundation of China(Grant Nos.11904289 and 61974120)the Fundamental Research Funds for the Central Universities(Grant Nos.3102019PY004,31020190QD010,and 3102019JC004)the Key Program for International Science and Technology Cooperation Projects of Shanxi Province(Grant No.2018KWZ-08)the National Key Research and Development Program of China(Grant No.2019YFC1520904)Key Research and Development Project of Shanxi Province(Grant Nos.2020GXLH-Z-027 and 2020ZDLGY04-08)the Natural Science Foundation of Shanxi Province(Grant Nos.2019JQ-613)the Foundation of the Education Department of Shanxi Province(Grant Nos.18JK0780)the start-up funds from Northwestern Polytechnical University(Grant Nos.19SH020159 and 19SH020123).
文摘MoS_(2) nanomaterial with the micro-pompon structure was synthesized by a surfactant-assisted hydrothermal method.The morphologies and structures of as-prepared MoS_(2) micro-pompon were investigated by adding different types of surfactants such as cetyltrimethyl ammonium bromide(CTAB),sodium dodecylbenzene sulphonate(SDBS),and polyvinyl pyrrolidone(PVP).The results indicated that the morphology of MoS_(2) could be controlled and changed effectively by the cationic sur-factant of CTAB.A reasonable growth mechanism for hollow structured MoS_(2) micro-pompon by hydrothermal processes was proposed.Further,photocatalytic degradation properties of MoS_(2) micro-pompon under visible light were evaluated by degradation of common organic dyes,which include rhodamine B(RhB),congo red,methyl orange,and methylene blue.The results indicated that MoS_(2) micro-pompon owned the highly selective catalytic ability to RhB with degradation efficiency of 95%in 60 min and 68%in 30 min.With the additive of the surfactant,the MoS_(2)-CTAB sample exhibited an enhanced ability of photocatalytic activity where degradation efficiency was improved to 92%in 30 min.The method employed in this work could be expanded to fabricate other sulfides with the controllable morphology and structure to further regulate the photocatalytic performance.
基金National Key Research and Development Program of China,Grant/Award Number:2020YFB2008501the Joint of the National Natural Science Foundation of China,Grant/Award Numbers:62288102,62371397,61974120+3 种基金the Natural Science Foundation of Shaanxi Province,Grant/Award Numbers:2022JQ-659,2023-JC-YB-495the Fundamental Research Funds for the Central UniversitiesNorthwestern Polytechnical UniversityOpen Test Funding Project from Analytical&Testing Center of Northwestern Polytechnical University,Grant/Award Number:2023T008。
文摘Two-dimensional transition metal dichalcogenides(2D TMDs)are promising as sensing materials for flexible electronics and wearable systems in artificial intelligence,tele-medicine,and internet of things(IoT).Currently,the study of 2D TMDs-based flexible strain sensors mainly focuses on improving the performance of sensitivity,response,detection resolution,cyclic stability,and so on.There are few reports on power consumption despite that it is of significant importance for wearable electronic systems.It is still challenging to effectively reduce the power consumption for prolonging the endurance of electronic systems.Herein,we propose a novel approach to realize ultra-low power consumption strain sensors by reducing the contact resistance between metal electrodes and 2D MoS_(2).A dendritic bilayer MoS_(2) has been designed and synthesized by a modified CVD method.Large-area edge contact has been introduced in the dendritic MoS_(2),resulting in decreased the contact resistance significantly.The contact resistance can be down to 5.4 kΩμm,which is two orders of magnitude lower than the conventional MoS_(2) devices.We fabricate a flexible strain sensor,exhibiting superior sensitivity in detecting strains with high resolution(0.04%)and an ultra-low power consumption(33.0 pW).This study paves the way for future wearable and flexible sensing electronics with high sensitivity and ultra-low power consumption.
基金financial support through the AcRF Tier1 grant(MOE2019-T1-002-087)the Singapore National Research Foundation for financial support under the Program of NRF-NRFI-2016-08financial support from the TUBA.
文摘Excitonics,an alternative to romising for processing information since semiconductor electronics is rapidly approaching the end of Moore’s law.Currently,the development of excitonic devices,where exciton flow is controlled,is mainly focused on electric-field modulation or exciton polaritons in high-Q cavities.Here,we show an alloptical strategy to manipulate the exciton flow in a binary colloidal quantum well complex through mediation of the Förster resonance energy transfer(FRET)by stimulated emission.In the spontaneous emission regime,FRET naturally occurs between a donor and an acceptor.In contrast,upon stronger excitation,the ultrafast consumption of excitons by stimulated emission effectively engineers the excitonic flow from the donors to the acceptors.Specifically,the acceptors’stimulated emission significantly accelerates the exciton flow,while the donors’stimulated emission almost stops this process.On this basis,a FRET-coupled rate equation model is derived to understand the controllable exciton flow using the density of the excited donors and the unexcited acceptors.The results will provide an effective alloptical route for realizing excitonic devices under room temperature operation.
