Preparation and application of cobalt oxide nanostructures as electrode materials for electrochemical supercapacitors

Abstract

In a reaction between cobalt(II) and ammonium oxalate in the presence of CTAB or F-127 as surfactant to control the particle size, a cobalt oxalate complex was formed. The precipitate was calcined and the resulting nano cobalt oxide was characterized by Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) methods. The crystalline pure and nano-sized particles had an average size of less than 40 nm. Electrochemical properties were examined by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. A maximum specific capacitance of 351 F g⁻¹ was obtained at a scan rate of 0.85 A g⁻¹ in 2 M of KOH solution for Co₃O₄@Ni foam electrode (Co₃O₄@NF). Furthermore, the electrode exhibits excellent cycle life stability, and almost 98.6% of its initial specific capacitance was maintained after 1000 cycle tests.