High performance microwave absorption(MA)materials especially those with tunable frequency are highly desirable for telecommunication industries and military camouflage in the information era.Herein,we constructed hie...High performance microwave absorption(MA)materials especially those with tunable frequency are highly desirable for telecommunication industries and military camouflage in the information era.Herein,we constructed hierarchical heterostructures based on VB-group laminated vanadium disulfide(VS_(2))nanosheets embedded with cobalt tetroxide(Co_(3)O_(4))nanoparticles.The highly dispersed Co_(3)O_(4)nanoparticles generate strong electromagnetic coupling networks that could enhance the loss properties of MA materials.Moreover,the interconnected VS_(2)layered network results in dipolar/interfacial polarization,multiple reflection and scattering favorable for the enhanced MA performance.Impressively,the maximum reflection loss of the VS_(2)/Co_(3)O_(4)hybrids containing 10%Co_(3)O_(4)can reach 57.96 dB at a thin thickness of 1.57 mm,and the bandwidth with an RL value less than-10 dB is as large as 3.5 GHz.The effective MA band could be adjusted in a range of 15.1 GHz(2.9-18 GHz)from S to Ku bands by the increase in thickness from 1.2 mm to 5.5 mm.The results show that the synergistic effect of multiple loss mechanisms and good impedance matching could be the reasons for strong MA capability in nearly all frequency bands,and thus,the high-performance and lightweight MA materials could be developed by the VS_(2)/Co_(3)O_(4)hybrids.展开更多
通过一种单步水热法成功制备了花状VS_2纳米片。利用X射线衍射仪(XRD)、拉曼光谱、场发射扫描电镜(SEM)和透射电子显微镜(TEM)等手段对样品进行表征,并研究了其生长机制。实验结果表明:反应温度及时间的不同直接影响着VS_2纳米片的形貌...通过一种单步水热法成功制备了花状VS_2纳米片。利用X射线衍射仪(XRD)、拉曼光谱、场发射扫描电镜(SEM)和透射电子显微镜(TEM)等手段对样品进行表征,并研究了其生长机制。实验结果表明:反应温度及时间的不同直接影响着VS_2纳米片的形貌。此外,通过使用VS_2纳米片作为锂离子电池阳极材料,分别研究了充放电电压和循环性能等性质。在200 m A/g电流密度下,电池初始充放电能力分别为195.4和90.6 m Ah/g。随着循环充放电的进行,该电极材料的库伦效率高达98%。可以认为VS_2纳米材料具备高效、高能量密度锂离子电池的阳极材料。展开更多
Portable and furnished electronics appliances demand power efficient energy storage devices where electrochemical supercapacitors gain much more attention.In this concern,a simple,low-cost and industry scalable succes...Portable and furnished electronics appliances demand power efficient energy storage devices where electrochemical supercapacitors gain much more attention.In this concern,a simple,low-cost and industry scalable successive ionic layer adsorption and reaction(SILAR)approach has been adopted to deposit nanostructured VS_2onto flexible and light-weight stainless steel(SS)substrate towards supercapacitor application.The nanocrystalline nature with hexagonal crystal structure has been confirmed for VS_2through structural analysis.The VS_2electrode exhibits a maximum specific capacitance of 349 F g^(-1)with a super stable behavior in three-electrode liquid-state configuration.Fabricated flexible symmetric solid-state supercapacitor(FSSC)device using gel electrolyte yields specific power of 1.5 k W kg^(-1)(specific energy of 25.9 Wh kg^(-1))with a widen voltage window of 1.6 V.A red LED has been glown for30 s using the system consisted of two devices in series combination.Furthermore,the system glows a combination of 21 red LEDs network with acronym‘VNIT’,demonstrating commercial exposure.The attribution of device demonstration even under mechanical stress holds great promise towards advanced flexible electronics application.展开更多
Heterostructures have lately been recognized as a viable implement to achieve high-energy Li-ion batteries(LIBs) because the as-formed built-in electric field can greatly accelerate the charge transfer kinetics. Herei...Heterostructures have lately been recognized as a viable implement to achieve high-energy Li-ion batteries(LIBs) because the as-formed built-in electric field can greatly accelerate the charge transfer kinetics. Herein, we have constructed the Mott-Schottky heterostructured VS2/MoS2 hybrids with tailorable 1T/2H phase based on their matchable formation energy, which are made of metallic and few-layered VS2 vertically grown on MoS2 surface. The density functional theory(DFT) calculations unveil that such heterojunctions drive the rearrangement of energy band with a facilitated reaction kinetics and enhance the Li adsorption energy more than twice compared to the MoS2 surface. Furthermore, the VS2 catalytically expedites the Li–S bond fracture and meantime the enriched Mo6+ enables the sulfur anchoring toward the oriented reaction with Li+to form Li2S, synergistically enhancing the reversibility of electrochemical redox. Consequently, the as-obtained VS2/MoS2 hybrids deliver a very large specific capacity of 1273 m Ah g^-1 at 0.1 A g^-1 with 61% retention even at 5 A g^-1. It can also stabilize 100 cycles at 0.5 A g^-1 and 500 cycles at 1 A g^-1. The findings provide in-depth insights into engineering heterojunctions towards the enhancement of reaction kinetics and reversibility for LIBs.展开更多
Although VB-Group transition metal disulfides(TMDs)VS_(2)nanomaterials with specific electronic properties and multiphase microstructures have shown fascinating potential in the field of electro-magnetic wave(EMW)abso...Although VB-Group transition metal disulfides(TMDs)VS_(2)nanomaterials with specific electronic properties and multiphase microstructures have shown fascinating potential in the field of electro-magnetic wave(EMW)absorption,the efficient utilization of VS_(2)is limited by the technical bottleneck of its narrow effective absorption bandwidth(EAB)which is attributed to environmental instability and a deficient electromagnetic(EM)loss mechanism.In order to fully exploit the maximal utilization values of VS_(2)nanomaterials for EMW absorption through mitigating the chemical instability and optimizing the EM parameters,biomass-based glucose derived carbon(GDC)like sugar-coating has been decorated on the surface of stacked VS_(2)nanosheets via a facile hydrothermal method,followed by high-temperature carbonization.As a result,the modulation of doping amount of glucose injection solution(Glucose)could effectively manipulate the encapsulation degree of GDC coating on VS_(2)nanosheets,further imple-menting the EM response mechanisms of the VS_(2)/GDC hybrids(coupling effect of conductive loss,interfacial polarization,relaxation,dipole polarization,defect engineering and multiple reflections and absorptions)through regulating the conductivity and constructing multi-interface heterostructures,as reflected by the enhanced EMW absorption performance to a great extent.The minimum reflection loss(Rmin)of VS_(2)/GDC hybrids could reach52.8 dB with a thickness of 2.7 mm at 12.2 GHz.Surprisingly,compared with pristine VS_(2),the EAB of the VS_(2)/GDC hybrids increased from 2.0 to 5.7 GHz,while their environmental stability was effectively enhanced by virtue of GDC doping.Obviously,this work provides a promising candidate to realize frequency band tunability of EMW absorbers with exceptional perfor-mance and environmental stability.展开更多
基金supported by the National Natural Science Foundation of China(51772160 and 51977009)China Postdoctoral Science Foundation(Grant No.2020M682029)Regional Joint Fund for Basic Research and Applied Basic Research of Guangdong Province(No.2020SA001515110905)。
文摘High performance microwave absorption(MA)materials especially those with tunable frequency are highly desirable for telecommunication industries and military camouflage in the information era.Herein,we constructed hierarchical heterostructures based on VB-group laminated vanadium disulfide(VS_(2))nanosheets embedded with cobalt tetroxide(Co_(3)O_(4))nanoparticles.The highly dispersed Co_(3)O_(4)nanoparticles generate strong electromagnetic coupling networks that could enhance the loss properties of MA materials.Moreover,the interconnected VS_(2)layered network results in dipolar/interfacial polarization,multiple reflection and scattering favorable for the enhanced MA performance.Impressively,the maximum reflection loss of the VS_(2)/Co_(3)O_(4)hybrids containing 10%Co_(3)O_(4)can reach 57.96 dB at a thin thickness of 1.57 mm,and the bandwidth with an RL value less than-10 dB is as large as 3.5 GHz.The effective MA band could be adjusted in a range of 15.1 GHz(2.9-18 GHz)from S to Ku bands by the increase in thickness from 1.2 mm to 5.5 mm.The results show that the synergistic effect of multiple loss mechanisms and good impedance matching could be the reasons for strong MA capability in nearly all frequency bands,and thus,the high-performance and lightweight MA materials could be developed by the VS_(2)/Co_(3)O_(4)hybrids.
基金Hunan Provincial Innovation Foundation for Postgraduate(CX2014B127)
文摘通过一种单步水热法成功制备了花状VS_2纳米片。利用X射线衍射仪(XRD)、拉曼光谱、场发射扫描电镜(SEM)和透射电子显微镜(TEM)等手段对样品进行表征,并研究了其生长机制。实验结果表明:反应温度及时间的不同直接影响着VS_2纳米片的形貌。此外,通过使用VS_2纳米片作为锂离子电池阳极材料,分别研究了充放电电压和循环性能等性质。在200 m A/g电流密度下,电池初始充放电能力分别为195.4和90.6 m Ah/g。随着循环充放电的进行,该电极材料的库伦效率高达98%。可以认为VS_2纳米材料具备高效、高能量密度锂离子电池的阳极材料。
文摘Portable and furnished electronics appliances demand power efficient energy storage devices where electrochemical supercapacitors gain much more attention.In this concern,a simple,low-cost and industry scalable successive ionic layer adsorption and reaction(SILAR)approach has been adopted to deposit nanostructured VS_2onto flexible and light-weight stainless steel(SS)substrate towards supercapacitor application.The nanocrystalline nature with hexagonal crystal structure has been confirmed for VS_2through structural analysis.The VS_2electrode exhibits a maximum specific capacitance of 349 F g^(-1)with a super stable behavior in three-electrode liquid-state configuration.Fabricated flexible symmetric solid-state supercapacitor(FSSC)device using gel electrolyte yields specific power of 1.5 k W kg^(-1)(specific energy of 25.9 Wh kg^(-1))with a widen voltage window of 1.6 V.A red LED has been glown for30 s using the system consisted of two devices in series combination.Furthermore,the system glows a combination of 21 red LEDs network with acronym‘VNIT’,demonstrating commercial exposure.The attribution of device demonstration even under mechanical stress holds great promise towards advanced flexible electronics application.
基金This work was supported by the National Natural Science Foundation of China(51672082,21975074 and 91534202)the Basic Research Program of Shanghai(17JC1402300)+2 种基金the Shanghai Scientific and Technological Innovation Project(18JC1410500)the National Program for Support of Top-Notch Young Professionalsthe Fundamental Research Funds for the Central Universities(222201718002).
文摘Heterostructures have lately been recognized as a viable implement to achieve high-energy Li-ion batteries(LIBs) because the as-formed built-in electric field can greatly accelerate the charge transfer kinetics. Herein, we have constructed the Mott-Schottky heterostructured VS2/MoS2 hybrids with tailorable 1T/2H phase based on their matchable formation energy, which are made of metallic and few-layered VS2 vertically grown on MoS2 surface. The density functional theory(DFT) calculations unveil that such heterojunctions drive the rearrangement of energy band with a facilitated reaction kinetics and enhance the Li adsorption energy more than twice compared to the MoS2 surface. Furthermore, the VS2 catalytically expedites the Li–S bond fracture and meantime the enriched Mo6+ enables the sulfur anchoring toward the oriented reaction with Li+to form Li2S, synergistically enhancing the reversibility of electrochemical redox. Consequently, the as-obtained VS2/MoS2 hybrids deliver a very large specific capacity of 1273 m Ah g^-1 at 0.1 A g^-1 with 61% retention even at 5 A g^-1. It can also stabilize 100 cycles at 0.5 A g^-1 and 500 cycles at 1 A g^-1. The findings provide in-depth insights into engineering heterojunctions towards the enhancement of reaction kinetics and reversibility for LIBs.
基金supported by the National Natural Science Foundation of China(52102368,52072192,51977009)Regional Joint Fund for Basic Research and Applied Basic Research of Guangdong Province(No.2020SA001515110905).
文摘Although VB-Group transition metal disulfides(TMDs)VS_(2)nanomaterials with specific electronic properties and multiphase microstructures have shown fascinating potential in the field of electro-magnetic wave(EMW)absorption,the efficient utilization of VS_(2)is limited by the technical bottleneck of its narrow effective absorption bandwidth(EAB)which is attributed to environmental instability and a deficient electromagnetic(EM)loss mechanism.In order to fully exploit the maximal utilization values of VS_(2)nanomaterials for EMW absorption through mitigating the chemical instability and optimizing the EM parameters,biomass-based glucose derived carbon(GDC)like sugar-coating has been decorated on the surface of stacked VS_(2)nanosheets via a facile hydrothermal method,followed by high-temperature carbonization.As a result,the modulation of doping amount of glucose injection solution(Glucose)could effectively manipulate the encapsulation degree of GDC coating on VS_(2)nanosheets,further imple-menting the EM response mechanisms of the VS_(2)/GDC hybrids(coupling effect of conductive loss,interfacial polarization,relaxation,dipole polarization,defect engineering and multiple reflections and absorptions)through regulating the conductivity and constructing multi-interface heterostructures,as reflected by the enhanced EMW absorption performance to a great extent.The minimum reflection loss(Rmin)of VS_(2)/GDC hybrids could reach52.8 dB with a thickness of 2.7 mm at 12.2 GHz.Surprisingly,compared with pristine VS_(2),the EAB of the VS_(2)/GDC hybrids increased from 2.0 to 5.7 GHz,while their environmental stability was effectively enhanced by virtue of GDC doping.Obviously,this work provides a promising candidate to realize frequency band tunability of EMW absorbers with exceptional perfor-mance and environmental stability.
