Green Synthesis of Cobalt (II, III) Oxide Nanoparticles using Moringa Oleifera Natural Extract as High Electrochemical Electrode for Supercapacitors

摘要

The research work involved the development of a better, inexpensive, reliable, easily and accurate way for the fabrication of Cobalt (II, III) oxide (Co_3O_4) nanoparticles through a green synthetic method using Moringa Oleifera extract. The electrochemical activity, crystalline structure, morphology, isothermal behaviour and optical properties of Co_3O_4 nanoparticles were studied using various characterization techniques. The X-ray diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS) analysis confirmed the formation of Co_3O_4 nanoparticles. The pseudo-capacitor behaviour of spinel Co_3O_4 nanoparticles on Nickel foam electrode was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 3M KOH solution. The CV curve revealed a pairs of redox peaks, indicating the pseudo-capacitive characteristics of the Ni/Co_3O_4 electrode. EIS results showed a small semicircle and Warburg impedance, indicating that the electrochemical process on the surface electrode is kinetically and diffusion controlled. The charge-discharge results indicating that the specific capacitance Ni/Co_3O_4 electrode is approximately 1060 F/g at a discharge current density of at 2 A/g.