Thermal-Assisted Electrochemical Synthesis of Cobalt Oxide Nanoparticles for Oxygen Evolution Reaction

In this study, the layers including Co₃O₄ nanoparticles were fabricated on the nickel foams using an electroplating method to be adopted for oxygen evolution reaction. Various times of 5, 10, and 15 minutes were considered to choose the optimal one for electrodeposition. The experiments were carried out at a temperature of 400°C under air atmosphere. The fabricated layers were electrochemically examined by means of various analyses, consisting of chronoamperometry (ChA), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV). Additionally, the layers were structurally and morphologically studied by different techniques such as field-emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR). The optimal electrodeposition time was determined as 10 min at which a layer possessing an appropriate thickness is obtained. However, at the time 20 min, electroplating led to generation of a layer showing a decrease in conductivity. Moreover, at 5 min, the fabricated layer manifested decreased active surface area in the oxygen evolution reaction. Worth mentioning that the layer electrodeposited at 10 min delivered a current density of 61.72 mA/cm² and a Tafel slope of 69 mV/dec, which were recorded at the potential of 1.65 V compared to a standard hydrogen electrode.