Facile Synthesis of Cu2O/RGO/Ni(OH)2 Nanocomposite and its Double Synergistic Effect on Supercapacitor Performance

A nanocomposite for supercapacitor electrode materials was designed and developed by integrating partially disabled Cu2O (low specific capacity, but high cycling ability) and Ni(OH)2 (low cyclability and high specific capacity) in the presence of reduced graphene oxide (RGO) nanosheets. Nanocomposite of Cu2O/RGO/Ni(OH)2 was directly grown on nickel foam (NF) through a facile one-pot hydrothermal process without any other reductant or oxidant, in which nickel foam acted as both a reductant of GO and Ni source, and a substrate for nanocomposite. The resultant Cu2O/RGO/Ni(OH)2 nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectrometer (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The electrochemical performance of the as-synthesized Cu2O/RGO/Ni(OH)2/NF electrodes were evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectrometry (EIS) in 6 mol L−1 KOH aqueous solution. This Cu2O/RGO/Ni(OH)2 nanocomposite exhibits superior capacitive performance: high capability (3969.3 mF cm−2 at 30 mA cm−2, i.e., 923.1 F g−1 at 7.0 A g−1), excellent cycling stability (92.4% retention even after 4,000 cycles, for RGO/Ni(OH)2/NF, 92.3% after 1,000 cycles), and good rate capacitance (50.3% capacity remaining at 200 mA cm−2).