Electrochemical Properties of Coke-Derived Graphene Oxide Reduced by Ascorbic Acid

Resumo

Abstract—The capacitive characteristics of reduced graphene oxide are investigated. The graphene is produced from coke by the modified Hummers method and then reduced by means of ascorbic acid. The curves obtained by cyclic voltammetry in acidic and alkaline electrolytes, with scanning of the potential at 10 mV/s, do not include pseudocapacitive peaks. Such peaks may be due to oxygen-bearing groups at the carbon surface. In the experiments, a two-electrode electrochemical supercapacitor cell is used, as well as a PARSTAT 4000 potentiostat–galvanostat. The greatest specific capacitance (310 F/g in the range from –1 V to +1 V at a scanning rate of 10 mV/s) and the lowest internal resistance of the cell are found for reduced graphene oxide in 2 M H₂SO₄ solution.