Advances in understanding the role of surface hole formation in heterogeneous water oxidation

The electrochemical oxidation of water to molecular oxygen, that is, the oxygen evolution reaction (OER), is a key anodic reaction that supplies electrons and protons for many technologically interesting reduction processes, such as carbon dioxide reduction and nitrogen fixation. Because the OER is a slow reaction, it needs to be facilitated by (photo)electro-catalysts. To develop such catalysts, advances in the mechanistic understanding of the OER are critical. In this opinion, we focus on a key aspect of the OER, namely, how the accumulation of oxidative charge ('holes') on the surface of a catalyst triggers O - O bond formation. We discuss recent advances in understanding the factors that drive surface hole formation at specific sites.