Enhanced electrochemical performance of NiO by addition of sulfonated graphene for supercapacitors
A facile approach for the fabrication of NiO/sulfonated graphene composites (NiO/sGNS) using ammonium carbamate as a precipitating agent was developed. With an enhanced specific surface area and a desirable surface chemical environment, the NiO/sulfonated graphene composites exhibit excellent electrochemical performance. The results from cyclic voltammetry (CV) demonstrate that traditional electrical double-layer capacitive processes contribute to improving the storage energy capabilities of the NiO/sGNS composites. Galvanostatic charge–discharge tests show that the specific capacitance of the NiO/sulfonated graphene composites increased to 530 F g−1 at a current density of 1.0 A g−1 in comparison with specific capacitances of 382 F g−1 for NiO/thermal reduced graphene composites (NiO/TRG) and 238 F g−1 for pristine NiO. Moreover, electrochemical impedance spectroscopy (EIS) indicates the considerable effect of sulfonated graphene on building electron and ion transport channels for faradaic reaction processes of the NiO/sGNS composites.