Three-dimensional cobalt oxide microstructures with brush-like morphology via surfactant-dependent assembly

In this study, three-dimensional cobalt oxide microstructures were developed. Cobalt oxide microdumbbells and microspheres, assembled by nanowires and primary particles, were successfully synthesized by a multistep hydrothermal method. Of all of the structures, the cobalt oxide microdumbbell electrode possesses the largest surface area of 70.8 m² g^-1 and the highest specific capacitance of 407.5 F g^-1. The as-prepared electrode also demonstrates excellent electrochemical stability and retains 97.5% of the initial capacitance after 2000 charge-discharge cycles. This performance is attributed to the desirable morphology, uniform microarchitecture stability, and high surface area. The results show that the as-fabricated Co₃O₄ is a promising electrode material for supercapacitor applications.