Abstract

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We have demonstrated that activated carbon could be produced via microwave-assisted activation at a much shorter time (ranging from 2-5 min) and reduced cost compared to the conventional activation method embraced by most researchers in the production of activated carbon. The research work is not only limited to surface chemistry and adsorption studies but also includes structural, microstructural and electrochemical studies/investigations of the produced Nickel Oxide Filled Activated Carbon (NOFAC). Its uniqueness is tied to cost effectiveness and the use of agricultural waste product. Activated carbon filled with nickel oxide was prepared via microwave-assisted chemical activation using coconut shell, palm kernel shell and their mixture with potassium hydroxide as activating agent. The effect of the incorporation of NiO on the structure and surface chemistry of the raw materials after activation was studied employing Fourier Transform Infra-Red (FTIR) Spectroscopy, Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) analysis. The electrochemical characteristics were investigated employing Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) analysis and Electrochemical Impedance Spectroscopy (EIS). The FTIR spectroscopy confirmed the existence of strong interfacial interaction between NiO and the host matrices showing creation and annihilation of absorption bands in the IR spectra with significant absorptions observed below 500cm-1 for nickel oxide. The TEM results showed that the microstructural evolution of host matrices is as a result of incorporation of NiO and activation using microwave power respectively. A follow-up with XRD confirmed the presence of anomalous graphite structure surrounded by traces of impurities resulting from the activating agent. Finally, the scan rate studies revealed activated palm kernel shell as the best candidate with better current response, higher value of specific capacitance and better electrochemical behaviour.

Keywords: Activated carbon, nickel oxide, microwave activation, supercapacitor electrode, microstructures, electrochemical behaviour.