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

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.