Dynamic Cation Intercalation Facilitating Chemical Oxidation of Water and Surface Stabilization During the Oxygen Evolution Reaction

A comprehensive understanding of the dynamic processes at the catalyst/electrolyte interfaces is crucial for the development of advanced electrocatalysts for the oxygen evolution reaction (OER). However, the chemical processes related to surface corrosion and catalyst degradation have not been well understood so far. In this study, we employ LiCoO₂ as a model catalyst and observe distinct OER activities and surface stabilities in different alkaline solutions. Operando X-ray diffraction (XRD) and online mass spectroscopy (OMS) measurements prove the selective intercalation of alkali cations into the layered structure of LiCoO₂ during OER. It is proposed that the dynamic cation intercalations facilitate the chemical oxidation process between highly oxidative Co species and adsorbed water molecules, triggering the so-called electrochemical-chemical reaction mechanism (EC-mechanism). The results of this study emphasize the influence of cations on OER and provide insights into new strategies for achieving both high activity and stability in high-performance OER catalysts.