Self-supported hydrothermal synthesized hollow Co3O4 nanowire arrays with high supercapacitor capacitance

Abstract

We report a facile hydrothermal synthesis method for the large-area growth of self-supported hollow Co₃O₄ nanowire arrays. The Co₃O₄ nanowires have an average diameter of 200 nm and grow vertically to the substrates forming aligned nanowire arrays. Interestingly, the as-prepared Co₃O₄ nanowire arrays combine properties of hollow structure and quasi-single crystallinity. A plausible formation mechanism of hollow Co₃O₄ nanowire arrays is proposed here. The Co₃O₄ nanowire arrays grown on the nickel foam are tested as a cathode electrode material for supercapacitor by cyclic voltammograms (CVs) and galvanostatic charge–discharge tests in 1 M KOH. The self-supported hollow Co₃O₄ nanowire arrays exhibit superior supercapacitor performances with high specific capacitances (599 F g⁻¹ at 2 A g⁻¹ and 439 F g⁻¹ at 40 A g⁻¹) as well as excellent cycle life, making them suitable for high-rate supercapacitor application. The enhanced supercapacitor performances are due to its unique porous structure providing fast ion and electron transfer, large reaction surface area and good strain accommodation.