Tanja Cuk and Jin Suntivich
Encyclopedia of Solid-Liquid Interfaces, Edited by Wandelt and BussettiÌý2023, DOI (current, online):Ìý
The oxygen evolution reaction (OER) from water is a critical component of a sustainable energy future; however, its mechanism has proved difficult to identify experimentally. This complexity is due to the elusive nature of electron and proton transferÌýintermediates that form within an interfacial water network and are buried at the solid–liquid interface. Here, we summarize recent measurements identifying the first two electron and proton transfer intermediates, e.g., OH∗ and O∗, on metallic oxide surfaces prior to the OER cycle, and the first electron and proton transfer intermediate, OH∗, as a metastable species during OER on a photo-excited, semiconducting oxide surface. These measurements provide information on the free energies of the intermediates, such that they can be used to approximate the reaction energy landscape of the catalytic cycle. We also highlight questions concerning the role that the interfacial environment (e.g., pH, interfacial water structure, and interfacial electric fields) plays in determining intermediate populations and their reaction kinetics.