▎ 摘　　要

A hydrothermal method assisted with freeze drying process was adopted to form composite supercapacitor materials of metastable vanadium dioxide [VO2(B)] nanobelts on reduced graphene oxide (RG) layers. The VO2(B) nanobelts were well dispersed on the graphene layers as verified by scanning electron microscopy and high-resolution transmission electron microscope. Cyclic voltammetry and galvanostatic charge-discharge measurements were adopted to investigate the electrochemical properties of VO2(B)/RG composites in 1.0 M Na2SO4 aqueous solution. The VO2(B)/RG composites delivered better specific capacitance and superior rate capability in comparison with the pure VO2(B). The initial specific capacitance of the composites reached 290.4 F g(-1) at 0.2 A g(-1) and maintained 82.3 % of the initial value after 1000 cycles at 2 A g(-1), 37.9 % higher than the pure VO2(B). Therefore, our results suggest that graphene greatly enhances the electrochemical performance of VO2(B) and VO2(B)/RG composite is a potential material for supercapacitor.