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.