Solvothermal synthesis of mesoporous NiCo2O4 spinel oxide nanostructure for high-performance electrochemical capacitor electrode

NiCo₂O₄ nanostructure was successfully synthesized via a d-glucose-assisted solvothermal process. Spinel-type cubic phase and mesoporous microstructure of the sample for different calcination temperatures were confirmed by X-ray diffraction and transmission electron microscopy. Typical pseudocapacitance feature of the NiCo₂O₄ treated at different temperatures was then evaluated in aqueous 6 M KOH electrolyte solution. Electrochemical measurements showed that the spinel nickel cobaltite nanostructure heated at 300 °C exhibits maximum specific capacitances of 524 F g^?1 at 0.5 A g^?1 and 419 F g^?1 at 10 A g^?1 with excellent cycle stability and only ~9 % of capacitance loss after 2,500 cycles. This demonstrates the potential application of the material for supercapacitors. The attractive pseudocapacitive performance of NiCo₂O₄ is mainly attributed to the redox contribution of the Ni and Co metal species, high surface area, and their desired mesoporous nanostructure.