The effect of temperature on the rate of oxygen evolution reaction during ferrate(VI) synthesis by anodic dissolution of iron in highly alkaline media

Abstract

This study investigates the effect of temperature on the rate of the oxygen evolution reaction (OER) during the electrochemical production of ferrate(VI) through anodic iron dissolution. We employed a membrane-divided electrochemical cell with a galvanostatically operated three-electrode setup. During the experiments, we recorded the anode potential at various temperatures and monitored temperature variations over time. Simultaneously, we measured the rates of ferrate(VI) formation and the oxygen evolution reaction. The latter, considered a parasitic reaction, competes with ferrate synthesis. By quantifying the extent to which the OER consumed the applied charge, we discovered that the OER rate decreases with temperature. Specifically, at 25 °C and 168 Am−2, the OER consumes more than double the charge of the produced ferrate, at higher temperatures the rate sensibly decays and with it the consumed charge by the OER. The specific energy required for ferrate(VI) production decreases as temperatures increase, aligning well with current efficiency and space-time yield values within the same temperature range.