V2O5/MXene纳米复合材料制备及储能性能

Preparation and energy storage properties of VO/MXene nanocomposites

利用氢氟酸(HF)刻蚀MAX(Ti3AlC2)相获得一种新型二维层状材料MXene(Ti3C2Tx),利用液相插层法扩大MXene材料层间距,然后在MXene表面分别负载纳米片状(NSV)和纳米带状(NBV)的五氧化二钒(V2O5).利用X射线衍射(XRD)、比表面积测试分析(BET)和高分辨场发射扫描电镜(FESEM)等手段对复合材料进行了结构表征.结果表明:MXene层间距增加;且两种形貌的五氧化二钒均匀的负载在MXene表面.这两种纳米复合材料的比表面积比MXene高,意味着它们可以为电化学反应提供更多的活性位点.利用多种电化学技术对V2O5,MXene和不同V2O5/MXene纳米复合材料在1.0 mol·L^-1 Na2SO4和1.0 mol·L^-1 LiNO3电解液中进行了电化学性能测试.结果表明:当电流密度为1 A·g^-1时,在1.0mol·L^-1Na2SO4电解液中MXene,V2O5,NSV/MXene和NBV/MXene的比电容分别为8.1,15.7,96.8和88.5F·g^-1;在1.0 mol·L^-1 LiNO3电解液中NSV/MXene和NBV/MXene的比电容分别为64.6,46.7,180.0和114.0 F·g^-1.表明所制备的NSV/MXene纳米复合材料是一种有研究和开发潜力的超级电容器电极材料.

Supercapacitors are usually used in new energy storage devices,communication technology,military,and aerospace fields due to their long lifecycle and high power density.Presently,it is imperative to find the electrode materials with low cost and excellent capacity.MXenes have received increasing attention due to their unique physical and chemical properties.They not only have superior electrical conductivity but also contain abundant surface groups(-OH,-F or-O);therefore,they are regarded as versatile 2D materials.MXenes can generate higher volumetric capacitance than that of graphene.However,MXene nanosheets are inclined to stack together,limiting the electrochemical properties of supercapacitors.In this work,an MXene(Ti3C2Tx)was obtained by etching an MAX(Ti3AlC2)phase using HF.To expand the interlayer spacing of Ti3C2Tx,the liquid-phase intercalation method was adopted.After the interlayer spacing was expanded,V2O5 nanosheet(NSV)and V2O5 nanobelt(NBV)were loaded on the MXene surface by a facile hydrothermal process.Their structure and morphology were characterized using different techniques,such as X-ray diffraction,Brunauer–Emmett–Teller surface area measurements,and field-emission scanning electron microscopy.The results show that the interlayer spacing of MXene is increased after liquid-phase intercalation,and NSV and NBV are uniformly loaded on the MXene surface.Moreover,the specific surface areas of the NSV/MXene and NSV/MXene nanocomposites are higher than that of the MXene;therefore,the nanocomposites can provide more active sites for electrochemical reactions.The electrochemical performances of the nanocomposites were investigated in 1.0 mol·L^-1 Na2SO4 and 1.0 mol·L^-1 LiNO3 aqueous solutions.The specific capacitances of V2O5,MXene,NSV/MXene,and NBV/MXene are 8.1,15.7,96.8,and 88.5 F·g^-1in 1.0 mol·L^-1 Na2SO4,respectively.When they are tested in 1.0 mol·L^-1 LiNO3,their specific capacitances are 64.6,46.7,180.0,and 114.0 F·g^-1,respectively.Therefore,the NSV/MXene nanocomposite is a potential electrode material for supercapacitors.