The structures and electronic properties of ZnO nanowires（NWs） of different diameters are investigated by employing the first-principles density functional theory. The results indicate that the oxygen vacancy（VO） ...The structures and electronic properties of ZnO nanowires（NWs） of different diameters are investigated by employing the first-principles density functional theory. The results indicate that the oxygen vacancy（VO） exerts a more evident influence on the band gap of the ZnO NWs. However, the effect will be weakened with the increase of the diameter. In addition, the energy band shifts downward due to the existence of VOand the offset decreases with the reduction of the VOconcentration. As the concentration of surface Zn atoms decreases, the conduction band shifts downward, while 2p electrons are lost in the oxygen vacancy, resulting in the split of valence band and the formation of an impurity level. Our findings agree well with the previous observations and will be of great importance for theoretical research based on ZnO NWs.展开更多
Silicon nanowires(Si NWs)have been widely researched as the best alternative to graphite anodes for the next-generation of high-performance lithium-ion batteries(LIBs)owing to their high capacity and low discharge pot...Silicon nanowires(Si NWs)have been widely researched as the best alternative to graphite anodes for the next-generation of high-performance lithium-ion batteries(LIBs)owing to their high capacity and low discharge potential.However,growing binder-free Si NW anodes with adequate mass loading and stable capacity is severely limited by the low surface area of planar current collectors(CCs),and is particularly challenging to achieve on standard pure-Cu substrates due to the ubiquitous formation of Li+inactive silicide phases.Here,the growth of densely-interwoven In-seeded Si NWs is facilitated by a thin-film of copper-silicide(CS)network in situ grown on a Cu-foil,allowing for a thin active NW layer(<10μm thick)and high areal loading(≈1.04 mg/cm^(2))binder-free electrode architecture.The electrode exhibits an average Coulombic efficiency(CE)of>99.6%and stable performance for>900 cycles with≈88.7%capacity retention.More significantly,it delivers a volumetric capacity of≈1086.1 m A h/cm^(3)at 5C.The full-cell versus lithium manganese oxide(LMO)cathode delivers a capacity of≈1177.1 m A h/g at 1C with a stable rate capability.This electrode architecture represents significant advances toward the development of binder-free Si NW electrodes for LIB application.展开更多
Resistive switching(RS)devices have great application prospects in the emerging memory field and neuromorphic field,but their stability and unclear RS mechanism limit their relevant applications.In this work,we constr...Resistive switching(RS)devices have great application prospects in the emerging memory field and neuromorphic field,but their stability and unclear RS mechanism limit their relevant applications.In this work,we construct a hydrogenated Au/SnO_(2)nanowire(NW)/Au device with two back-to-back Schottky diodes and investigate the RS characteristics in air and vacuum.We find that the Ion/Io ff ratio increases from 20 to 10^(4)when the read voltage decreases from 3.1 V to^(-1)V under the condition of electric field.Moreover,the rectification ratio can reach as high as 10^4owing to oxygen ion migration modulated by the electric field.The nanodevice also shows non-volatile resistive memory characteristic.The RS mechanism is clarified based on the changes of the Schottky barrier width and height at the interface of Au/SnO_(2)NW/Au device.Our results provide a strategy for designing high-performance memristive devices based on SnO_(2)NWs.展开更多
To further improve the performance of binders,a SiHfBCN-based high-temperature resistant adhesive was successfully synthesized by Polymer-Derived Ceramics(PDC)route using TiB2,Polysiloxane(PSO)and short SiC nanowires ...To further improve the performance of binders,a SiHfBCN-based high-temperature resistant adhesive was successfully synthesized by Polymer-Derived Ceramics(PDC)route using TiB2,Polysiloxane(PSO)and short SiC nanowires as fillers.The effect of short SiC nanowires on the adhesive strength at room temperature and high temperature,as well as the reinforcing mechanism was studied.Compared with the adhesive without SiC nanowires,after curing(at 170℃)and pyrolysis(at 1000℃)in air,the appropriate adding of SiC nanowires upgrades the room temperature and high temperature(at 1000℃ in air)adhesive strength to(12.50±0.67)MPa(up by about 32%)and(13.11±0.79)MPa(up by about 106%),respectively.Attractively,under the synergistic impact of the nanowire bridging,nanowire breaking,nanowire drawing and crack deflection,the optimized adhesive exhibits multi-stage fracture,causing the increscent fracture displacement.展开更多
综述了与外来植物入侵相关的理论假说。并主要介绍了从化感角度提出的“N ove lW eapons”假说(NW假说)。某些外来入侵植物能产生一些化学物质。这些物质可以发挥较强的化感作用,或者成为植物和土壤微生物之间相互作用的调节者。由于不...综述了与外来植物入侵相关的理论假说。并主要介绍了从化感角度提出的“N ove lW eapons”假说(NW假说)。某些外来入侵植物能产生一些化学物质。这些物质可以发挥较强的化感作用,或者成为植物和土壤微生物之间相互作用的调节者。由于不同区域的植物群落共同进化的轨迹不同,被入侵群落的植物对这些化学物质缺乏适应性,因此,这些物质成为了外来种入侵的利器。而对外来种发源地的群落来说,由于长期的共存关系,这些物质对其伴生植物的影响相对较小。NW假说为化感作为外来植物入侵的一种机制奠定了理论基础,为外来入侵植物的防治提供了理论依据,但作为一种较新的理论假说,还需要更多的实验研究加以支持。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51132002 and 11574261)the Natural Science Foundation of Hebei ProvinceChina(Grant No.A2015203261)
文摘The structures and electronic properties of ZnO nanowires（NWs） of different diameters are investigated by employing the first-principles density functional theory. The results indicate that the oxygen vacancy（VO） exerts a more evident influence on the band gap of the ZnO NWs. However, the effect will be weakened with the increase of the diameter. In addition, the energy band shifts downward due to the existence of VOand the offset decreases with the reduction of the VOconcentration. As the concentration of surface Zn atoms decreases, the conduction band shifts downward, while 2p electrons are lost in the oxygen vacancy, resulting in the split of valence band and the formation of an impurity level. Our findings agree well with the previous observations and will be of great importance for theoretical research based on ZnO NWs.
基金funded by the Science Foundation Ireland (SFI)under the Principal Investigator Program under contract No.11PI-1148,16/IA/4629 and SFI 16/M-ERA/3419funding under the European Union’s Horizon 2020 Research and Innovation Program+7 种基金grant agreement No.814464 (Si-DRIVE project)IRCLA/2017/285 and SFI Research Centres AMBER,Ma REI and CONFIRM 12/RC/2302_P2,12/RC/2278_P2,and 16/RC/3918SFI for SIRG grant No.18/SIRG/5484support from the Sustainable Energy Authority of Ireland through the Research Development and Demonstration Funding Program (Grant No.19/RDD/548)Enterprise Ireland through the Innovation Partnership Program (Grant No.IP 20190910)support from the SFI Research Centre Ma REI (award reference No.12/RC/2302_P2)support from the SFI Industry RD&I Fellowship Program (21/IRDIF/9876)the EU Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Individual Fellowship Grant (843621)。
文摘Silicon nanowires(Si NWs)have been widely researched as the best alternative to graphite anodes for the next-generation of high-performance lithium-ion batteries(LIBs)owing to their high capacity and low discharge potential.However,growing binder-free Si NW anodes with adequate mass loading and stable capacity is severely limited by the low surface area of planar current collectors(CCs),and is particularly challenging to achieve on standard pure-Cu substrates due to the ubiquitous formation of Li+inactive silicide phases.Here,the growth of densely-interwoven In-seeded Si NWs is facilitated by a thin-film of copper-silicide(CS)network in situ grown on a Cu-foil,allowing for a thin active NW layer(<10μm thick)and high areal loading(≈1.04 mg/cm^(2))binder-free electrode architecture.The electrode exhibits an average Coulombic efficiency(CE)of>99.6%and stable performance for>900 cycles with≈88.7%capacity retention.More significantly,it delivers a volumetric capacity of≈1086.1 m A h/cm^(3)at 5C.The full-cell versus lithium manganese oxide(LMO)cathode delivers a capacity of≈1177.1 m A h/g at 1C with a stable rate capability.This electrode architecture represents significant advances toward the development of binder-free Si NW electrodes for LIB application.
基金Chenzhou Science and Technology Plan Project of China(Grant No.ZDYF2020159)Scientific Research Project of Hunan Provincial Department of Education(Grant No.21C0708)。
文摘Resistive switching(RS)devices have great application prospects in the emerging memory field and neuromorphic field,but their stability and unclear RS mechanism limit their relevant applications.In this work,we construct a hydrogenated Au/SnO_(2)nanowire(NW)/Au device with two back-to-back Schottky diodes and investigate the RS characteristics in air and vacuum.We find that the Ion/Io ff ratio increases from 20 to 10^(4)when the read voltage decreases from 3.1 V to^(-1)V under the condition of electric field.Moreover,the rectification ratio can reach as high as 10^4owing to oxygen ion migration modulated by the electric field.The nanodevice also shows non-volatile resistive memory characteristic.The RS mechanism is clarified based on the changes of the Schottky barrier width and height at the interface of Au/SnO_(2)NW/Au device.Our results provide a strategy for designing high-performance memristive devices based on SnO_(2)NWs.
基金co-supported by the National Natural Science Foundation of China (No. 52061135102)the Innovation Training Foundation for College Students of Northwestern Polytechnical University, China (No. 202310699180)the Creative Research Foundation of the Science and Technology on Thermostructural Composite Materials Laboratory
文摘To further improve the performance of binders,a SiHfBCN-based high-temperature resistant adhesive was successfully synthesized by Polymer-Derived Ceramics(PDC)route using TiB2,Polysiloxane(PSO)and short SiC nanowires as fillers.The effect of short SiC nanowires on the adhesive strength at room temperature and high temperature,as well as the reinforcing mechanism was studied.Compared with the adhesive without SiC nanowires,after curing(at 170℃)and pyrolysis(at 1000℃)in air,the appropriate adding of SiC nanowires upgrades the room temperature and high temperature(at 1000℃ in air)adhesive strength to(12.50±0.67)MPa(up by about 32%)and(13.11±0.79)MPa(up by about 106%),respectively.Attractively,under the synergistic impact of the nanowire bridging,nanowire breaking,nanowire drawing and crack deflection,the optimized adhesive exhibits multi-stage fracture,causing the increscent fracture displacement.
文摘综述了与外来植物入侵相关的理论假说。并主要介绍了从化感角度提出的“N ove lW eapons”假说(NW假说)。某些外来入侵植物能产生一些化学物质。这些物质可以发挥较强的化感作用,或者成为植物和土壤微生物之间相互作用的调节者。由于不同区域的植物群落共同进化的轨迹不同,被入侵群落的植物对这些化学物质缺乏适应性,因此,这些物质成为了外来种入侵的利器。而对外来种发源地的群落来说,由于长期的共存关系,这些物质对其伴生植物的影响相对较小。NW假说为化感作为外来植物入侵的一种机制奠定了理论基础,为外来入侵植物的防治提供了理论依据,但作为一种较新的理论假说,还需要更多的实验研究加以支持。
