Electrochemical capacitance of porous reduced graphene oxide/nickel foam

Porous reduced graphene oxide (rGO) supported on nickel foam (NF) had been prepared for electrochemical supercapacitor application. The GO/NF was synthesized by depositing graphene oxide on NF through ultrasonic-assisted coating process. The rGO/NF was formed through chemical reduction treatment of GO/NF using hydrazine hydrate. The hydrothermal reduced graphene oxide/nickel foam (HrGO/NF) was formed through hydrothermal reduction treatment of rGO/NF using hydrazine hydrate. The morphology and microstructure of HrGO/NF were characterized by scanning electron microscopy, transmission electron microscope and Raman spectroscopy. The electrochemical capacitance performance was investigated by cyclic voltammetry and galvanostatic charge/discharge measurements. The specific capacitance was increased from 112.5 F g(-1) for rGO/NF up to 334 F g(-1) for HrGO/NF at a current density of 0.3 A g(-1) when only the mass of rGO was considered. The hydrothermal reduction treatment of rGO could well promote its electrical conductivity, which accordingly contributed to its improved capacitance performance of HrGO. The capacitance retention kept 99.6 % after 1,000 charge/discharge cycles even at a high current density of 4.0 A g(-1), presenting a good cycling stability. The aqueous supercapacitor was also constructed using two symmetric electrodes of HrGO/NF and KOH electrolyte, exhibiting the energy density of 4.2 Wh kg(-1) and the power density of 1.0 kW kg(-1) at a current density of 2.0 A g(-1). These results indicated the potential application of HrGO/NF as supercapacitor electrode material.