One-pot hydrothermal synthesis of reduced graphene oxide/Ni(OH)2 films on nickel foam for high performance supercapacitors

Reduced graphene oxide (RGO) on nickel hydroxide (Ni(OH)2) film was synthesized via a green and facile hydrothermal approach. In this process, graphene oxide (GO) was reduced by nickel foam (NF) while the nickel metal was oxidized to Ni(OH)2 film simultaneously, which resulted in RGO on Ni(OH)2 structure. The RGO/Ni(OH)2 composite film was characterized using by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscope (FESEM). The electrochemical performances of the supercapacitor with the as-synthesized RGO/Ni(OH)2 composite films as electrodes were evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectrometry (EIS) in 1 M KOH aqueous solution. Results indicated that the RGO/Ni(OH)2/NF composite electrodes exhibited superior capacitive performance with high capability (2500 mF cm−2 at a current density of 5 mA cm−2, or 1667 F g−1 at 3.3 A g−1), compared with pure Ni(OH)2/NF (450 mF cm−2 at 5 mA cm−2, 409 F g−1 at 3.3 A g−1) prepared under the identical conditions. Our study highlights the importance of anchoring RGO films on Ni(OH)2 surface for maximizing the optimized utilization of electrochemically active Ni(OH)2 and graphene for energy storage application in supercapacitors.