Unveiling the influence of electrolyte pH on the structural evolution of cobalt oxide pre-catalyst in oxygen evolution reaction

The pH effects play a critical role in electro-catalysis, yet their influence on the structural evolution of electrocatalysts during the oxygen evolution reaction (OER) remains underexplored. In this study, we combined in-situ Raman and UV–Vis spectroscopy with density functional theory (DFT) calculations to track the structural evolution of electrodeposited amorphous cobalt (oxy)hydroxide under different pH conditions. Our findings reveal distinct responses of the synthesized catalyst to varying electrolyte pH levels. The formation of relatively ordered β-CoOOH structure from amorphous cobalt (oxy)hydroxide under alkaline conditions may serve as the active phase, while the less active amorphous cobalt (oxy)hydroxide remained stable under neutral conditions. This study emphasizes the pivotal role of electrolyte pH in driving surface reconstruction of metal oxides, even in the absence of applied electrode potential.