Highly ordered mesoporous NiCo2O4 with superior pseudocapacitance performance for supercapacitors

Abstract

Conventional NiCo₂O₄ without mesopores prepared by direct thermal decomposition of an appropriate solution mixture consisting of Co(NO₃)₂·6H₂O and Ni(NO₃)₂·6H₂O does not provide superior pseudocapacitance performance due to the inadequate redox reaction during the charge and discharge process when used as an electrode material for pseudocapacitors. In this work, we demonstrate the synthesis of highly ordered mesoporous NiCo₂O₄ by a nanocasting method and examine its electrochemical performance by means of cyclic voltammetry and the galvanostatic charge–discharge method. The highly ordered mesoporous NiCo₂O₄ prepared using mesoporous silica KIT-6 as a template presents an exceptionally high specific capacitance (1699 F g⁻¹ at a current density of 1 A g⁻¹) and an excellent cycling stability (∼104.1% retention after 10 000 cycles). In addition, other 3D mesoporous nanostructures (mesoporous Co₃O₄ and mesoporous NiO) synthesized by a similar nanocasting method also show outstanding pseudocapacitive performance. Thus, the effective design of highly ordered mesoporous electrodes demonstrated in this work offers a promising strategy for supercapacitors with superior electrochemical properties.