Urchin-like Co3O4 microspherical hierarchical superstructures constructed by one-dimension nanowires toward electrochemical capacitors

Abstract

We describe in this report a novel synthetic strategy for synthesizing urchin-like Co3O4 microspherical hierarchical superstructures constructed by one-dimension Co3O4 nanowires, precipitating hydroxides followed by a calcinating process. Electrochemical data reveals that the as-synthesized urchin-like Co3O4 superstructures can deliver a specific capacitance (SC) of 614 F g−1 at a current density of 1 A g−1, and remain as large as 536 F g−1 at 4 A g−1 in a 3 M KOH aqueous solution. Such unique urchin-like hierarchical superstructures facilitate the electrolyte ions and electrons to easily contact the electroactive Co3O4 nanowire building blocks at high rates, which allows for sufficient Faradaic reactions to take place at large current densities for energy storage. Moreover, a SC degradation of ca. 23% after 5 000 continuous charge–discharge cycles at a large current density of 4 A g−1 demonstrates their good electrochemical stability at high rates.