Hydrothermally reduced graphene oxide as a supercapacitor

•Hydrothermal reduced GO contains few oxygen containing groups.•The supercapacitance behavior of RGO composed of both electrical double layer capacitance and pseudocapacitance.•The stability of the hydrothermally RGO capacitor was characterized over 1000 cycles.•RGO can be used as an effective electrode material in supercapacitors because of its high power and energy densities. The supercapacitance behavior of hydrothermally reduced graphene oxide (RGO) was investigated for the first time. The capacitive behavior of RGO was characterized by using cyclic voltammetry and galvanostatic charge–discharge methods. The specific capacitance of hydrothermally reduced RGO at 1A/g was 367F/g in 1M H2SO4 electrolyte, which was higher than that of RGO synthesized via the hydrazine reduction method. The RGO-modified glassy carbon electrode showed excellent stability. After 1000 cycles, the supercapacitance was 107.7% of that achieved in the 1st cycle, which suggests that RGO has excellent electrochemical stability as a supercapacitor electrode material. The energy density of hydrothermal RGO reached 44.4Wh/kg at a power density of 40kW/kg.