Graphene/vanadium oxide hybrid electrodes for electrochemical capacitor

• Graphene/vanadium oxide hybrid electrodes were prepared by one-step simultaneous hydrothermal-reduction technology.
• The hydrothermal treatment made the reduction of graphite oxide to graphene and the formation of VOx·nH2O nanoplates.
• An obviously synergistic effect existed between VOx·nH2O nanoplates and graphenes.
• RG (0.5)/VOx·nH2O electrode exhibited a high specific capacitance of 384 F g−1 and excellent cycle stability.

Graphene/vanadium oxide (RG/VOx·nH2O) hybrid electrodes with different graphene (RG) amounts were prepared by one-step simultaneous hydrothermal-reduction technology in a suspension of NH4VO3, NH2CSNH2 and graphite oxide (GO) nanosheets. The hydrothermal treatment made the reduction of GO to RG and the formation of VOx·nH2O nanoplates. The graphene nanolayers were dispensed on the surface of VOx·nH2O nanoplates, and further intimated contact between the RG nanosheets and VOx·nH2O nanoplates, which caused the mesoporous structure derived from the self-assembly between RG nanosheets and VOx·nH2O nanoplates and the high active utilization of VOx·nH2O. 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 VOx·nH2O nanoplates and GR nanosheets. RG (0.5)/VOx·nH2O 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 K2SO4 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.

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