Carbon-nanoparticles encapsulated in hollow nickel oxides for supercapacitor application

Monodisperse carbon nanoparticles encapsulated in hollow NiO nanostructures (C@NiO) have been successfully synthesized by calcination from a Ni(OH)2 covered carbon (C@Ni(OH)2) precursor. The as-prepared products at each stage were extensively characterized and carefully discussed. The electrochemical properties of the carbon encapsulated in hollow NiO nanostructures were investigated using cycling voltammetry and charge–discharge techniques. The specific capacitance of the obtained C@NiO electrode was about 988.7 F g−1 at a current density of 0.5 A g−1. It shows better performance than hollow NiO spheres obtained in oxygen atmosphere. Furthermore, the C@NiO electrode shows a good capacitive retention of ca. 90.7% after 1000 charge–discharge cycles.