The properties of a metal-oxide-semiconductor device on a single layer MoS_(2)(molybdenum disulfide)semiconductor are determined theoretically utilizing the concept of physics that the carrier effective masses in mate...The properties of a metal-oxide-semiconductor device on a single layer MoS_(2)(molybdenum disulfide)semiconductor are determined theoretically utilizing the concept of physics that the carrier effective masses in materials are related to the intrinsic Fermi energy levels in materials by the universal mass-energy equivalence equation given as dE/E=dm/m,where E is the energy and m is the mass of the free electron.The known parameters of electron effective mass of 0.48 m and the direct bandgap of 1.8 eV for monolayer MoS_(2) semiconductor are utilized to determine the properties of the MOS(metal-oxide-semiconductor)device,with the given previous research consequence that the threshold for electron heating in SiO_(2) is 2 MV/cm-eV.展开更多
The development of renewable and affordable energy is crucial for building a sustainable society. In this context, establishing a sustainable infrastructure for renewable energy requires the integration of energy stor...The development of renewable and affordable energy is crucial for building a sustainable society. In this context, establishing a sustainable infrastructure for renewable energy requires the integration of energy storage, specifically use of renewable hydrogen. The hydrogen evolution reaction (HER) of electrochemical water splitting is a promising method for producing green hydrogen. Recently, two-dimensional nanomaterials have shown great promise in promoting the HER in terms of both fundamental research and practical applications due to their high specific surface areas and tunable electronic properties. Among them, molybdenum disulfide (MoS2), a non-noble metal catalyst, has emerged as a promising alternative to replace expensive platinum-based catalysts for the HER because MoS_(2)has a high inherent activity, low cost, and abundant reserves. At present, greatly improved activity and stability are urgently needed for MoS_(2)to enable wide deployment of water electrolysis devices. In this regard, efficient strategies for precisely modifying MoS_(2)are of interest. Herein, the progress made with MoS_(2)as an HER catalyst is reviewed, with a focus on modification strategies, including phase engineering, morphology design, defect engineering, heteroatom doping, and heterostructure construction. It is believed that these strategies will be helpful in designing and developing high-performance and low-cost MoS2-based catalysts by lowering the charge transfer barrier, increasing the active site density, and optimizing the surface hydrophilicity. In addition, the challenges of MoS_(2)electrocatalysts and perspectives for future research and development of these catalysts are discussed.展开更多
Recently, two-dimensional monolayer molybdenum disulfide(MoS_2), a transition metal dichalcogenide, has received considerable attention due to its direct bandgap, which does not exist in its bulk form, enabling applic...Recently, two-dimensional monolayer molybdenum disulfide(MoS_2), a transition metal dichalcogenide, has received considerable attention due to its direct bandgap, which does not exist in its bulk form, enabling applications in optoelectronics and also thanks to its enhanced catalytic activity which allows it to be used for energy harvesting. However,growth of controllable and high-quality monolayers is still a matter of research and the parameters determining growth mechanism are not completely clear. In this work, chemical vapor deposition is utilized to grow monolayer MoS_2 flakes while deposition duration and temperature effect have been systematically varied to develop a better understanding of the MoS_2 film formation and the influence of these parameters on the quality of the monolayer flakes. Different from previous studies, SEM results show that single-layer MoS_2 flakes do not necessarily grow flat on the surface, but rather they can stay erect and inclined at different angles on the surface, indicating possible gas-phase reactions allowing for monolayer film formation. We have also revealed that process duration influences the amount of MoO_3/MoO_2 within the film network. The homogeneity and the number of layers depend on the change in the desorption–adsorption of radicals together with sulfurization rates, and, inasmuch, a careful optimization of parameters is crucial. Therefore, distinct from the general trend of MoS_2 monolayer formation, our films are rough and heterogeneous with monolayer MoS_2 nanowalls. Despite this roughness and the heterogeneity, we observe a strong photoluminescence located around 675 nm.展开更多
MoS2 is a promising anode material for sodium ion batteries owing to its two-dimensional layered structure and high specific capacity. But it still exhibits a poor cycle stability and limited rate capability for Na＋ ...MoS2 is a promising anode material for sodium ion batteries owing to its two-dimensional layered structure and high specific capacity. But it still exhibits a poor cycle stability and limited rate capability for Na＋ storage because of its poor electrical conductivity and structural instability. In this work, MoS2/graphite composite is fabricated by mechanically delaminated and restacked MoS2 and graphite to form two-dimensional composite layers. The graphite sheets will improve electrical conductivity and prevent the aggregation as well as structure collapse of the MoS2 layers during charge-discharge process. The MoS2/graphite composite exhibits excellent Na＋ storage properties. It delivers a high discharge specific capacity of 358.2 mAh/g at a current density of 100 mA]g in the first discharge process and with capacity retention of 68.1% after 800 cycles （retains 244 mAh/g）. The average discharge specific capacities retain 250.9 and 225.4 mAh/g corresponding to the current densities of 100 and 1000 mA]g, showing excellent rate capability. The improved electrochemical performance is attributed to the improved electrical conductivity and structural stability after composition of graphite sheets. The study demonstrates a new research strategy for improving sodium ion storage properties of Mo52.展开更多
Due to their unique characteristics,two-dimensional(2D)materials have drawn great attention as promising candidates for the next generation of integrated circuits,which generate a calculation unit with a new working m...Due to their unique characteristics,two-dimensional(2D)materials have drawn great attention as promising candidates for the next generation of integrated circuits,which generate a calculation unit with a new working mechanism,called a logic transistor.To figure out the application prospects of logic transistors,exploring the temperature dependence of logic characteristics is important.In this work,we explore the temperature effect on the electrical characteristic of a logic transistor,finding that changes in temperature cause transformation in the calculation:logical output converts from‘AND’at 10 K to‘OR’at 250 K.The transformation phenomenon of temperature regulation in logical output is caused by energy band which decreases with increasing temperature.In the experiment,the indirect band gap of MoS2 shows an obvious decrease from 1.581 eV to 1.535 eV as the temperature increases from 10 K to 250 K.The change of threshold voltage with temperature is consistent with the energy band,which confirms the theoretical analysis.Therefore,as a promising material for future integrated circuits,the demonstrated characteristic of 2D transistors suggests possible application for future functional devices.展开更多
Ti_(3)C_(2)T_(x)MXene fiber has shown extraordinary potential for supercapacitor electrode in wearable elec-tronics and textile energy storage,but realizing high energy density and practical-powered applications remai...Ti_(3)C_(2)T_(x)MXene fiber has shown extraordinary potential for supercapacitor electrode in wearable elec-tronics and textile energy storage,but realizing high energy density and practical-powered applications remains a great challenge.Here,we report a covalent-architected molybdenum disulfide-Ti_(3)C_(2)T_(x)(MoS_(2)-Ti_(3)C_(2)T_(x))core-shell fiber for high-performance supercapacitor.Benefiting from the microfluidic and micro-reaction strategies,the ordered MoS_(2)arrays are strongly bridged on Ti_(3)C_(2)T_(x)fiber via Ti-O-Mo bond,re-sulting in large exposed surface,enhanced porosity and excellent interfacial conduction for charges high diffusion and faradaic transfer.The MoS_(2)-Ti_(3)C_(2)T_(x)fiber exhibits ultra-large capacitance of 2028 F cm^(-3)and admirable reversibility in 1 M H_(2)SO_(4)aqueous electrolyte.Meanwhile,MoS_(2)-Ti_(3)C_(2)T_(x)fiber-based solid-state supercapacitor presents high energy density of 23.86 mWh cm^(-3),capacitance of 1073.6 F cm^(-3)and superior cycling ability of 92.13%retention after 20,000 cycles,which can realize stable energy supply for wearable watch,LEDs,electric fans,toy ship and self-powered devices.Our work may provide an insight-ful guidance for the advanced design of structural fiber towards robust new energy and next-generation wearable industry.展开更多
Two-dimensional(2D)materials have come to light due to their unique thickness that owns abundant exposed edges with enhanced electrocatalytic properties.2D molybdenum disulfide(MoS_(2))nanosheet has aroused considerab...Two-dimensional(2D)materials have come to light due to their unique thickness that owns abundant exposed edges with enhanced electrocatalytic properties.2D molybdenum disulfide(MoS_(2))nanosheet has aroused considerable attention due to its tunable surface chemistry and high electrochemical sur-face area.Nonetheless,several shortcomings associated with MoS_(2),such as its naturally existing semi-conducting 2H phase,which has limited active sites due to the inert basal plane,restrict its application in water electrocatalysis.Taking into account the benefits of the 1T/2H phase of MoS_(2),as well as the importance of engineering 2D/2D heterojunction interface for boosted electrocatalysis,metallic Ti_(3)C_(2)Tx was integrated with 1T/2H MoS_(2) to develop 2D/2D 1T/2H MoS_(2)/Ti_(3)C_(2)Tx heterostructured nanocompos-ites.Herein,with only 25%of the intercalating agent,1T/2H MoS_(2) with the highest 1T phase content of~82%was successfully synthesized.It was further incorporated with 1 wt%of Ti_(3)C_(2)Tx through a com-bination of ultrasonication and mechanical stirring process.The 1T/2H MoS_(2)(25D)/Ti_(3)C_(2)Tx-1(MTC-1)manifested outstanding electrocatalytic performance with an overpotential and Tafel slope of 280 mV(83.80 mV dec^(-1))and 300 mV(117.2 mV dec^(-1)),for catalyzing acidic and alkaline medium HER,respec-tively.Pivotally,the as-prepared catalysts also illustrated long-term stability for more than 40 h.The coupling method for the 2D nanosheets is crucial to suppress the oxidation of Ti_(3)C_(2)Tx and the restack-ing issue of 2D nanosheets.The superior HER activity is ascribed to the synergistic effect between the heterostructure,enhancing the electronic structure and charge separation capability.The intrinsic prop-erty of the catalyst further confirms by turnover frequency(TOF)calculation.As such,this research paves the way for designing high-efficiency 2D electrocatalysts and sheds light on the further advancement of tunable 2D electrocatalysts for robust water splitting and beyond.展开更多
High performance supercapacitors coupled with mechanical flexibility are needed to drive flexible and wearable electronics that have anesthetic appeal and multi-functionality. Two dimensional（2D） materials have attr...High performance supercapacitors coupled with mechanical flexibility are needed to drive flexible and wearable electronics that have anesthetic appeal and multi-functionality. Two dimensional（2D） materials have attracted attention owing to their unique physicochemical and electrochemical properties, in addition to their ability to form hetero-structures with other nanomaterials further improving mechanical and electrochemical properties. After a brief introduction of supercapacitors and 2D materials, recent progress on flexible supercapacitors using 2D materials is reviewed. Here we provide insights into the structure–property relationships of flexible electrodes, in particular free-standing films. We also present our perspectives on the development of flexible supercapacitors.展开更多
Electrocatalysts with high efficiency are crucial for improving the storage capacity and electrochemical stability of lithium–oxygen batteries(LOBs).In this work,through a facile hydrothermal method,cobalt–nitrogen-...Electrocatalysts with high efficiency are crucial for improving the storage capacity and electrochemical stability of lithium–oxygen batteries(LOBs).In this work,through a facile hydrothermal method,cobalt–nitrogen-doped carbon nanocubes(Co–N/C),the calcination products of zeolitic imidazolate framework(ZIF–67)are encapsulated by ultrathin C–MoS_(2) nanosheets to obtain Co–N/C@C–MoS_(2) composites which are used as host materials for the oxygen cathode.The synergistic effect between Co–N_(x) active sites and Mo–N coupling centers effectively promotes the formation and decomposition of Li_(2)O_(2) during repeated discharge and charge process.The mesoporous C–MoS_(2) nanosheets with delicately designed morphology facilitate charge transfer and account for improved reaction kinetics and more importantly,suppressed side reactions between the carbon materials and the electrolyte.The oxygen cathode with the Co–N/C@C–MoS_(2)host shows a high initial discharge specific capacity of 21197 mAh g^(-1)and a long operation life of 332 cycles.Theoretical calculation provides in-depth explanation for the reaction mechanism and offers insights for the rational design of electrocatalysts for LOBs.展开更多
Ion based synaptic devices(ISDs)are one of the excellent candidates for neuromorphic computing.However,most of ISDs utilized additional ion sources to supply ions for adjusting the conductance of the device channel,wh...Ion based synaptic devices(ISDs)are one of the excellent candidates for neuromorphic computing.However,most of ISDs utilized additional ion sources to supply ions for adjusting the conductance of the device channel,which might hinder the large-scale integration for fabricating hierarchical artificial neural network.Here a high-performance monolayer MoS_(2) ISD is demonstrated using Na^(+)ions doped in MoS_(2) lattice as ion sources.Benefited from the Na^(+)ions and S vacancy defects in the MoS_(2) lattice,the device not only exhibits various synaptic plasticity(long-and short-term plasticity)and typical biological features(pain-perceptual nociceptors and associative learning),but also has a low synaptic event response voltage(100 mV)and a low energy consumption(0.92 pJ)for a synaptic event.A dissociation-adsorptionmigration-binding model is proposed to elaborate the resistance switching mechanism,which is corroborated by density functional theory calculations and characterizations.In addition,an artificial neural network(ANN)based on MoS_(2) ISDs is simulated for the recognition of the MNIST handwritten digits.The deviation of the recognition accuracy is less than 8%compared to the ideal floating-point numeric precision.These results provide a new strategy for fabricating high-performance ISDs for neuromorphic computing.展开更多
文摘The properties of a metal-oxide-semiconductor device on a single layer MoS_(2)(molybdenum disulfide)semiconductor are determined theoretically utilizing the concept of physics that the carrier effective masses in materials are related to the intrinsic Fermi energy levels in materials by the universal mass-energy equivalence equation given as dE/E=dm/m,where E is the energy and m is the mass of the free electron.The known parameters of electron effective mass of 0.48 m and the direct bandgap of 1.8 eV for monolayer MoS_(2) semiconductor are utilized to determine the properties of the MOS(metal-oxide-semiconductor)device,with the given previous research consequence that the threshold for electron heating in SiO_(2) is 2 MV/cm-eV.
基金the Outstanding Youth Project of Guangdong Provincial Natural Science Foundation,China(Grant No.2022B1515020020)the National Natural Science Foundation of China(Grant No.2225071013)+2 种基金the Guangdong Basic and Applied Basic Research Foundation,China(No.2022B1515120079)the Funding by Science and Technology Projects in Guangzhou,China(No.202206050003)the Guangdong Engineering Technology Research Center for Hydrogen Energy and Fuel Cells,China.
文摘The development of renewable and affordable energy is crucial for building a sustainable society. In this context, establishing a sustainable infrastructure for renewable energy requires the integration of energy storage, specifically use of renewable hydrogen. The hydrogen evolution reaction (HER) of electrochemical water splitting is a promising method for producing green hydrogen. Recently, two-dimensional nanomaterials have shown great promise in promoting the HER in terms of both fundamental research and practical applications due to their high specific surface areas and tunable electronic properties. Among them, molybdenum disulfide (MoS2), a non-noble metal catalyst, has emerged as a promising alternative to replace expensive platinum-based catalysts for the HER because MoS_(2)has a high inherent activity, low cost, and abundant reserves. At present, greatly improved activity and stability are urgently needed for MoS_(2)to enable wide deployment of water electrolysis devices. In this regard, efficient strategies for precisely modifying MoS_(2)are of interest. Herein, the progress made with MoS_(2)as an HER catalyst is reviewed, with a focus on modification strategies, including phase engineering, morphology design, defect engineering, heteroatom doping, and heterostructure construction. It is believed that these strategies will be helpful in designing and developing high-performance and low-cost MoS2-based catalysts by lowering the charge transfer barrier, increasing the active site density, and optimizing the surface hydrophilicity. In addition, the challenges of MoS_(2)electrocatalysts and perspectives for future research and development of these catalysts are discussed.
基金supported by Anadolu University BAP 1407F335 and BAP 1505F271 Projects
文摘Recently, two-dimensional monolayer molybdenum disulfide(MoS_2), a transition metal dichalcogenide, has received considerable attention due to its direct bandgap, which does not exist in its bulk form, enabling applications in optoelectronics and also thanks to its enhanced catalytic activity which allows it to be used for energy harvesting. However,growth of controllable and high-quality monolayers is still a matter of research and the parameters determining growth mechanism are not completely clear. In this work, chemical vapor deposition is utilized to grow monolayer MoS_2 flakes while deposition duration and temperature effect have been systematically varied to develop a better understanding of the MoS_2 film formation and the influence of these parameters on the quality of the monolayer flakes. Different from previous studies, SEM results show that single-layer MoS_2 flakes do not necessarily grow flat on the surface, but rather they can stay erect and inclined at different angles on the surface, indicating possible gas-phase reactions allowing for monolayer film formation. We have also revealed that process duration influences the amount of MoO_3/MoO_2 within the film network. The homogeneity and the number of layers depend on the change in the desorption–adsorption of radicals together with sulfurization rates, and, inasmuch, a careful optimization of parameters is crucial. Therefore, distinct from the general trend of MoS_2 monolayer formation, our films are rough and heterogeneous with monolayer MoS_2 nanowalls. Despite this roughness and the heterogeneity, we observe a strong photoluminescence located around 675 nm.
基金supported by the National Natural Science Foundation of China(no.21403099)the Natural Science Funds for Distinguished Young Scholars of Gansu Province(no.1606RJDA320)
文摘MoS2 is a promising anode material for sodium ion batteries owing to its two-dimensional layered structure and high specific capacity. But it still exhibits a poor cycle stability and limited rate capability for Na＋ storage because of its poor electrical conductivity and structural instability. In this work, MoS2/graphite composite is fabricated by mechanically delaminated and restacked MoS2 and graphite to form two-dimensional composite layers. The graphite sheets will improve electrical conductivity and prevent the aggregation as well as structure collapse of the MoS2 layers during charge-discharge process. The MoS2/graphite composite exhibits excellent Na＋ storage properties. It delivers a high discharge specific capacity of 358.2 mAh/g at a current density of 100 mA]g in the first discharge process and with capacity retention of 68.1% after 800 cycles （retains 244 mAh/g）. The average discharge specific capacities retain 250.9 and 225.4 mAh/g corresponding to the current densities of 100 and 1000 mA]g, showing excellent rate capability. The improved electrochemical performance is attributed to the improved electrical conductivity and structural stability after composition of graphite sheets. The study demonstrates a new research strategy for improving sodium ion storage properties of Mo52.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61925402,61851402,and 61734003)Science and Technology Commission of Shanghai Municipality,China(Grant No.19JC1416600)+1 种基金National Key Research and Development Program of China(Grant No.2017YFB0405600)Shanghai Education Development Foundation and Shanghai Municipal Education Commission Shuguang Program,China(Grant No.18SG01).
文摘Due to their unique characteristics,two-dimensional(2D)materials have drawn great attention as promising candidates for the next generation of integrated circuits,which generate a calculation unit with a new working mechanism,called a logic transistor.To figure out the application prospects of logic transistors,exploring the temperature dependence of logic characteristics is important.In this work,we explore the temperature effect on the electrical characteristic of a logic transistor,finding that changes in temperature cause transformation in the calculation:logical output converts from‘AND’at 10 K to‘OR’at 250 K.The transformation phenomenon of temperature regulation in logical output is caused by energy band which decreases with increasing temperature.In the experiment,the indirect band gap of MoS2 shows an obvious decrease from 1.581 eV to 1.535 eV as the temperature increases from 10 K to 250 K.The change of threshold voltage with temperature is consistent with the energy band,which confirms the theoretical analysis.Therefore,as a promising material for future integrated circuits,the demonstrated characteristic of 2D transistors suggests possible application for future functional devices.
基金This work was financially supported by the National Natu-ral Science Foundation of China(Nos.22278378,22208190,and 21706120)the Natural Science Foundation of Jiangsu Province(No.BK20211592)+2 种基金the National Postdoctoral Program for Innovative Tal-ents(No.BX2021146)the Shuimu Tsinghua Scholar Program(No.2021SM055)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Ti_(3)C_(2)T_(x)MXene fiber has shown extraordinary potential for supercapacitor electrode in wearable elec-tronics and textile energy storage,but realizing high energy density and practical-powered applications remains a great challenge.Here,we report a covalent-architected molybdenum disulfide-Ti_(3)C_(2)T_(x)(MoS_(2)-Ti_(3)C_(2)T_(x))core-shell fiber for high-performance supercapacitor.Benefiting from the microfluidic and micro-reaction strategies,the ordered MoS_(2)arrays are strongly bridged on Ti_(3)C_(2)T_(x)fiber via Ti-O-Mo bond,re-sulting in large exposed surface,enhanced porosity and excellent interfacial conduction for charges high diffusion and faradaic transfer.The MoS_(2)-Ti_(3)C_(2)T_(x)fiber exhibits ultra-large capacitance of 2028 F cm^(-3)and admirable reversibility in 1 M H_(2)SO_(4)aqueous electrolyte.Meanwhile,MoS_(2)-Ti_(3)C_(2)T_(x)fiber-based solid-state supercapacitor presents high energy density of 23.86 mWh cm^(-3),capacitance of 1073.6 F cm^(-3)and superior cycling ability of 92.13%retention after 20,000 cycles,which can realize stable energy supply for wearable watch,LEDs,electric fans,toy ship and self-powered devices.Our work may provide an insight-ful guidance for the advanced design of structural fiber towards robust new energy and next-generation wearable industry.
基金Ministry of Higher Education(MOHE)Malaysia under the Fundamental Research Grant Scheme(FRGS)(Ref No:FRGS/1/2020/TK0/XMU/02/1)We would also like to thank the Ministry of Science,Technology and Innovation(MOSTI)Malaysia under the Strategic Research Fund(SRF-APP)(S.22015)+5 种基金The authors would also like to acknowledge the financial support provided by the National Natural Science Foundation of China(Ref No.22202168)Guangdong Basic and Applied Basic Re-search Foundation(Ref No.2021A1515111019)We would also like to acknowledge the financial support from the State Key Labo-ratory of Physical Chemistry of Solid Surfaces,Xiamen University(No.2023X11)This work is also funded by Xiamen University Malaysia Investigatorship Grant(Grant No.IENG/0038)Xiamen University Malaysia Research Fund(ICOE/0001,XMUMRF/2021-C8/IENG/0041 and XMUMRF/2019-C3/IENG/0013)Hengyuan International Sdn.Bhd.(Grant No.EENG/0003).
文摘Two-dimensional(2D)materials have come to light due to their unique thickness that owns abundant exposed edges with enhanced electrocatalytic properties.2D molybdenum disulfide(MoS_(2))nanosheet has aroused considerable attention due to its tunable surface chemistry and high electrochemical sur-face area.Nonetheless,several shortcomings associated with MoS_(2),such as its naturally existing semi-conducting 2H phase,which has limited active sites due to the inert basal plane,restrict its application in water electrocatalysis.Taking into account the benefits of the 1T/2H phase of MoS_(2),as well as the importance of engineering 2D/2D heterojunction interface for boosted electrocatalysis,metallic Ti_(3)C_(2)Tx was integrated with 1T/2H MoS_(2) to develop 2D/2D 1T/2H MoS_(2)/Ti_(3)C_(2)Tx heterostructured nanocompos-ites.Herein,with only 25%of the intercalating agent,1T/2H MoS_(2) with the highest 1T phase content of~82%was successfully synthesized.It was further incorporated with 1 wt%of Ti_(3)C_(2)Tx through a com-bination of ultrasonication and mechanical stirring process.The 1T/2H MoS_(2)(25D)/Ti_(3)C_(2)Tx-1(MTC-1)manifested outstanding electrocatalytic performance with an overpotential and Tafel slope of 280 mV(83.80 mV dec^(-1))and 300 mV(117.2 mV dec^(-1)),for catalyzing acidic and alkaline medium HER,respec-tively.Pivotally,the as-prepared catalysts also illustrated long-term stability for more than 40 h.The coupling method for the 2D nanosheets is crucial to suppress the oxidation of Ti_(3)C_(2)Tx and the restack-ing issue of 2D nanosheets.The superior HER activity is ascribed to the synergistic effect between the heterostructure,enhancing the electronic structure and charge separation capability.The intrinsic prop-erty of the catalyst further confirms by turnover frequency(TOF)calculation.As such,this research paves the way for designing high-efficiency 2D electrocatalysts and sheds light on the further advancement of tunable 2D electrocatalysts for robust water splitting and beyond.
基金Funding from the Australian Research Council Centre of Excellence Scheme(CE 140100012)the funding from National Natural Science Foundation of China(51502206)+1 种基金the CSC scholarship from the Ministry of Education of PR Chinathe support of the CSC scholarship from the Ministry of Education of PR China
文摘High performance supercapacitors coupled with mechanical flexibility are needed to drive flexible and wearable electronics that have anesthetic appeal and multi-functionality. Two dimensional（2D） materials have attracted attention owing to their unique physicochemical and electrochemical properties, in addition to their ability to form hetero-structures with other nanomaterials further improving mechanical and electrochemical properties. After a brief introduction of supercapacitors and 2D materials, recent progress on flexible supercapacitors using 2D materials is reviewed. Here we provide insights into the structure–property relationships of flexible electrodes, in particular free-standing films. We also present our perspectives on the development of flexible supercapacitors.
基金Postdoctoral Science Foundation(Grant No.172731)Key R&D and Transformation Projects in Qinghai Province(No.2021-HZ-808)the Talents Project of Beijing Municipal Committee Organization Deparment(No.2018000021223ZK21)。
文摘Electrocatalysts with high efficiency are crucial for improving the storage capacity and electrochemical stability of lithium–oxygen batteries(LOBs).In this work,through a facile hydrothermal method,cobalt–nitrogen-doped carbon nanocubes(Co–N/C),the calcination products of zeolitic imidazolate framework(ZIF–67)are encapsulated by ultrathin C–MoS_(2) nanosheets to obtain Co–N/C@C–MoS_(2) composites which are used as host materials for the oxygen cathode.The synergistic effect between Co–N_(x) active sites and Mo–N coupling centers effectively promotes the formation and decomposition of Li_(2)O_(2) during repeated discharge and charge process.The mesoporous C–MoS_(2) nanosheets with delicately designed morphology facilitate charge transfer and account for improved reaction kinetics and more importantly,suppressed side reactions between the carbon materials and the electrolyte.The oxygen cathode with the Co–N/C@C–MoS_(2)host shows a high initial discharge specific capacity of 21197 mAh g^(-1)and a long operation life of 332 cycles.Theoretical calculation provides in-depth explanation for the reaction mechanism and offers insights for the rational design of electrocatalysts for LOBs.
基金National Natural Science Foundation of China(NSFC)(No.62274021)thanks to eceshi(www.eceshi.com)for the DFT calculations.
文摘Ion based synaptic devices(ISDs)are one of the excellent candidates for neuromorphic computing.However,most of ISDs utilized additional ion sources to supply ions for adjusting the conductance of the device channel,which might hinder the large-scale integration for fabricating hierarchical artificial neural network.Here a high-performance monolayer MoS_(2) ISD is demonstrated using Na^(+)ions doped in MoS_(2) lattice as ion sources.Benefited from the Na^(+)ions and S vacancy defects in the MoS_(2) lattice,the device not only exhibits various synaptic plasticity(long-and short-term plasticity)and typical biological features(pain-perceptual nociceptors and associative learning),but also has a low synaptic event response voltage(100 mV)and a low energy consumption(0.92 pJ)for a synaptic event.A dissociation-adsorptionmigration-binding model is proposed to elaborate the resistance switching mechanism,which is corroborated by density functional theory calculations and characterizations.In addition,an artificial neural network(ANN)based on MoS_(2) ISDs is simulated for the recognition of the MNIST handwritten digits.The deviation of the recognition accuracy is less than 8%compared to the ideal floating-point numeric precision.These results provide a new strategy for fabricating high-performance ISDs for neuromorphic computing.
