The Effects of Alkali Metal Cations on Oxygen Evolution in Acidic and Basic Electrolytes

The choice of electrolyte in electrocatalytic systems can significantly impact measured performance. While these effects are well documented, a clear explanation remains lacking. Here, we demonstrate that alkali metal cations have a promoting effect on the oxygen evolution reaction (OER) over iridium (Ir) catalysts, even when accounting for the confounding effects of pH. Additionally, we show that the cations’ promoting effect is more prominent in relatively high pH levels and becomes insignificant as the electrolyte is made strongly acidic. In the absence of cations, we find a positive correlation between acidity and activity for OER over Ir catalysts. We hypothesize that cations favorably interact with reaction intermediates and help optimize interactions between the catalyst surface and key adsorbates. These experiments further our understanding of the role of the electrolyte in controlling electrocatalytic activity.