Synthesis and controlled sulfidation of Ni-Co alloy on reduced graphene oxide as an electrode with enhanced conductivity and capacitance for supercapacitors

Highlights: • Ni-Co-S/Ni-Co/RGO hybrid is fabricated via the partial sulfidation of Ni-Co alloy. • Partial retention of Ni-Co alloy makes the hybrid retain higher conductivity. • A hybrid with good stability and enhanced conductivity and capacitance is obtained. • The strategy to optimize the capacitor performance is effective. In this study, the partially sulfidized Ni-Co/reduced graphene oxide (NCS/NC/RGO) hybrid was developed as a supercapacitor electrode material. Because Ni-Co sulfide (NCS) possessed good pseudocapacitor property and non-sulfidized Ni-Co (NC) alloy had high conductivity, we attempted to optimize the electrochemical performance of NCS/NC/RGO hybrid by controlling the sulfidation of NC/RGO hybrid. RGO was incorporated as a substrate to help the dispersion of NCS/NC nanoparticles and contribute some capacitance. It was demonstrated that an appropriate sulfidation of NC/RGO hybrid could lead to the highest capacitance effectively. Moreover, the optimal NCS/NC/RGO hybrid also exhibited good stability. The result revealed that the strategy to optimize the capacitor performance of NCS/NC/RGO hybrid via the controlled sulfidation of NC/RGO hybrid was indeed effective.