Preparation of nanospherical porous NiO by a hard template route and its supercapacitor application

•Nanospherical porous NiO was synthesized by a facile hard template method.•The material possesses high surface area and superior mesoporous structure.•The prepared NiO electrodes exhibit prominent specific capacitance.

A nanospherical porous NiO electrode material was successfully prepared by a nanocasting method using porous carbon nanospheres as a hard template. The obtained porous NiO materials were characterized with high crystalline degree, larger surface area than 200 m2 g-1, 5–6 nm mesoporous channels and nanospherical morphology with 500–700 nm in diameter, which render them excellent electrochemical performance. The galvanostatic charge–discharge measurements demonstrated that the optimal electrode possessed a high specific capacitance of 1201 F g−1 at a discharge current density of 0.5 A g−1. In addition, specific capacitances at different discharge current densities indicated a good capacitance at high current density and electrochemical impedance spectra suggested low charge transfer resistance of the electrodes. It also exhibited cycling stability of 70% capacity retention after 500 continuous charge/discharge cycles.