MnO2@Co3O4 nanocomposite based electrocatalyst for effective oxygen evolution reaction

Abstract

For large-scale energy applications, conceiving low-cost and simple earth-abundant electrocatalysts are more difficult. By using an aqueous chemical technique, MnO₂ was added into Co₃O₄ with varying concentrations to prepare MnO₂@Co₃O₄ nanocomposite (CM). In an aqueous solution of 1 M KOH, the electrocatalyst with a greater concentration of MnO₂ outperforms in terms of OER. To confirm the composition, crystalline structure, and morphology of the electrocatalyst, analytical methods such as X-ray diffraction (XRD) techniques, Fourier transformed infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used. At 20 mA/cm² current density, the electrocatalyst had a lowest overpotential of 310 mV verses Reversible hydrogen electrode (RHE). The CM-0.4 electrocatalyst has a small Tafel slope value and charge transfer resistance of approximately 72 mV/dec and 74 Ω which confirm its high catalytic activity. The electrocatalyst reveals a double layer capacitance (R_ct) of 18 µF/cm² and an electrochemical active surface area (ECSA) of 450 cm², demonstrating that addition of MnO₂ impurities into Co₃O₄ enhances the active catalyst sites. These findings contribute to the knowledge of these kind of catalysts, that will assist in the development of novel electrocatalysts which are feasible for prospective energy generation technologies.