Selective synthesis of hierarchical mesoporous spinel NiCo ₂O₄ for high-performance supercapacitors

Hierarchical mesoporous spinel NiCo₂O₄ was synthesized by a facile hydrothermal method assisted by polyvinylpyrrolidone (PVP) and a post annealing treatment. The synthesized hierarchical mesoporous NiCo₂O₄ presents a hierarchical mesoporous structure with diameters of 5.0 and 25 nm, respectively. Compared to conventional flower-like NiCo₂O₄, the hierarchical mesoporous structured NiCo ₂O₄ exhibits excellent supercapacitor performance. The specific capacitance can reach 1619.1 F g^-1 at a current density of 2.0 A g^-1. When the current density is increased to 10.0 A g ^-1, a specific capacitance of 571.4 F g^-1 can be obtained. Furthermore, the hierarchical mesoporous structured NiCo₂O ₄ presents excellent stability. The outstanding electrochemical performance of the hierarchical mesoporous NiCo₂O₄ reveals its potential to be a promising material for use in supercapacitors, and also inspires continued research on binary metal oxides as energy transformation materials.