Self-assembly of hierarchical 3D starfish-like Co<inf>3</inf>O<inf>4</inf> nanowire bundles on nickel foam for high-performance supercapacitor

Abstract

Recently Co3O4-based nanostructures have received great interests owing to their potential applications as supercapacitor. In this work, novel three-dimensional (3D) starfish-like Co3O4 nanowire bundles on nickel foam (Co3O4-oNF) were successfully prepared via a facile hydrothermal method. The phase/micro structure and morphology of the sample were identified by X-ray diffraction, scanning and transmission electron microscopy, respectively, and demonstrated a unique 1D–3D combined mesoporous nanostructure. Cyclic voltammetry, chronopotentiometry, and impedance measurements were employed to characterize the electrochemical performance of the specimen in 3.0 M KOH solution, and show that the Co3O4-oNF not only has a superior specific capacitance of 1399.28 F g−1 at a current density of 1.0 A g−1 but also exhibits reliable capacitance retention of 92.26 % after 1000 cycles even at a high current density of 12.5 A g−1. The Nyquist plot reveals that the internal resistance of the specimen is merely 0.9 Ω, indicating that the starfish-like Co3O4 has a solid mechanical bonding with the nickel substrate. The synthesized 3D nanostructured Co3O4 holds great promises for applications in supercapacitor.