Honeycomb-like open-edged reduced-graphene-oxide (rGO)-incorporated NiO/Co3O4 as advanced cathodes as hybrid supercapacitors for energy storage device applications

Abstract

Honeycomb-like open-edged reduced-graphene-oxide nanosheets (HOrGO NSs) filled with transition metal oxides (TMOs) as Co₃O₄/NiO nanoparticles (NPs) have been synthesized by a simple and cost-effective hydrothermal-calcination route. The properties of the prepared materials were studied by powder X-ray diffraction, scanning electron microscopy, TEM, XPS, and Brunauer−Emmett−Teller techniques. The hybrid electrode has a high specific capacity of 1345 Fg⁻¹ at 1 Ag⁻¹ with a superior rate performance of 93.6% capacity retention even at a current density of 1 Ag⁻¹. Moreover, the assembled Co₃O₄/NiO/rGO//AC hybrid supercapacitor achieves excellent performance with a maximum voltage of 1.6 V and a high energy density of 65.2 Whkg⁻¹ at a power density of 780 Wkg⁻¹ and excellent cycle stability performance with a capacity retention of 98.1% after 10,000 cycles. The excellent electrochemical performance is probably attributed to highly dispersed cobalt and nickel oxides nanoparticles on rGO nanosheets. This can increase the electron conductivity, provide more exposed electroactive sites, and facilitate the faradaic redox processes.