Fabrication of nanoporous NiO@CoO composites by dealloying method as ultra-high capacitance electrodes

Transition metal oxide materials prepared by dealloying method have attracted more and more attention and researches due to their high theoretical specific capacitance. In this study, nanoporous NiO@CoO composite electrodes were facilely synthesized by the melting and in situ corrosion, which exhibits an excellent electrochemical performance. The superior performance is ascribed to the reasonable pore size distribution (average pore diameter of 5.1 nm) and high specific surface area (50.75 m² g⁻¹) of the NiO@CoO, which provides a fast channel for electrolyte ions, shorten the free path of ion transfer and provide sufficient active sites for redox reactions. Moreover, the as-prepared material demonstrates a highest specific capacitance of 18.4 F cm⁻² at a current density of 10 mA cm⁻², and exhibits an excellent cycling stability with 93.9% retention after 5000 cycles at 30 mA cm⁻². In a word, owing to the porous structure and pseudocapacitance effect, the NiO@CoO composite electrode has an ultra-high performance, which proves that this study has a great research value in the field of supercapacitors.