Influence of addition of cobalt oxide on microstructure and electrochemical capacitive performance of nickel oxide

Abstract

Ni–Co oxide nanocomposite was prepared by thermal decomposition of the precursor obtained via a new method—coordination homogeneous coprecipitation method. The synthesized sample was characterized physically by X-ray diffraction, scanning electron microcopy, energy dispersive spectrum, transmission electron microscope, and Brunauer–Emmett–Teller surface area measurement, respectively. Electrochemical characterization of Ni–Co oxide electrode was examined by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance measurements in 6-mol L−1 KOH aqueous solution electrolyte. The results indicated that the addition of cobalt oxide not only changed the morphology of NiO but also enhance its electrochemical capacitance value. A specific capacitance value of 306 F g−1 of Ni–Co oxide nanocomposite with n Co = 0.5 (n Co is the mole fraction of Co with respect to the sum of Co and Ni) was measured at the current density of 0.2 A g−1, nearly 1.5 times greater than that of pure NiO electrode. Lower resistance and better rate capability can also be observed.