Graphene/vanadium oxide hybrid electrodes for electrochemical capacitor

Abstract Graphene/vanadium oxide (RG/VO x · n H 2 O) hybrid electrodes with different graphene (RG) amounts were prepared by one-step simultaneous hydrothermal-reduction technology in a suspension of NH 4 VO 3 , NH 2 CSNH 2 and graphite oxide (GO) nanosheets. The hydrothermal treatment made the reduction of GO to RG and the formation of VO x · n H 2 O nanoplates. The graphene nanolayers were dispensed on the surface of VO x · n H 2 O nanoplates, and further intimated contact between the RG nanosheets and VO x · n H 2 O nanoplates, which caused the mesoporous structure derived from the self-assembly between RG nanosheets and VO x · n H 2 O nanoplates and the high active utilization of VO x · n H 2 O. The vanadium was existed in a mixed valance, and some V (V) could be reduced into V (ІV) by the carbon on the graphene nanosheets. An obviously synergistic effect was existed between VO x · n H 2 O nanoplates and GR nanosheets. RG (0.5)/VO x · n H 2 O electrode with RG content of 10 wt% exhibited not only high specific capacitance of 384 F g −1 at a scan rate of 5 mV s −1 in 0.5 mol L −1 K 2 SO 4 electrolyte, but also relatively good cycle stability at a current density of 5 A g −1 (60% capacitance retention after 1000 cycles), which made it has a potential application as a supercapacitor electrode material.