Enhanced Electrochemical Performance of MnCo_1.5Fe_0.5O₄Spinel for Oxygen Evolution Reaction through Heat Treatment

MnCo_1.5Fe_0.5O₄ spinel oxide was synthesized using the sol-gel technique, followed by heat treatment at various temperatures (400, 600, 800, and 1000 °C). The prepared materials were examined as anode electrocatalysts for water-splitting systems in alkaline environments. Solid-state characterization methods, such as powder X-ray diffraction and X-ray absorption spectroscopy (XAS), were used to analyze the materials’ crystallographic structure and surface characteristics. The intrinsic activity of the MnCo_1.5Fe_0.5O₄ was fine-tuned by altering the electronic structure by controlling the calcination temperature, and the highest activity was observed for the sample treated at 800 °C. A shift in the valence state of surface cations under oxidative conditions in an alkaline solution during the oxygen evolution reaction was detected through ex situ XAS measurements. Moreover, the influence of the experimental conditions on the electrocatalytic performance of the material, including the pH of the electrolyte and the temperature, was demonstrated.