Low-temperature and template-free fabrication of cobalt oxide acicular nanotube arrays and their applications in supercapacitors

Abstract

Layered cobalt carbonate hydroxide (LCCH) acicular nanorod arrays (ANRAs) grown on a graphite substrate are converted to Co₃O₄ acicular nanotube arrays (ANTAs) via the anion-exchange reaction and Kirkendall effect at low temperature. The Co₃O₄ ANTAs exhibit an area capacitance of 369 mF cm⁻² and a specific capacitance of 979 F g⁻¹ at 2.5 mA cm⁻², which are much higher than those of the Co₃O₄ ANRAs prepared by calcining the LCCH ANRAs at 350 °C (64.5 mF cm⁻² and 191 F g⁻¹).