Implications of Nonelectrochemical Reaction Steps on the Oxygen Evolution Reaction: Oxygen Dimer Formation on Perovskite Oxide and Oxynitride Surfaces

According to the conventional understanding, oxygen evolution reaction on metal oxide surfaces involves four proton-coupled electron transfer steps with *OH, *O, and *OOH intermediates. Recently, several alternative mechanisms lower overpotentials were proposed for highly active catalysts. While such additional intermediates leading nonelectrochemical could be considered, they are usually neglected when thermodynamic overpotential of is investigated. We show here that this a valid approximation endothermic steps, which only affect kinetics, while exothermic can also overpotential. basis density functional theory calculations one those different perovskite oxides oxynitrides. find weakly binding *O adsorbate spontaneously adopts bidentate bridged dimer structure in step an energy gain excess 1 eV. This decrease free needs compensated by equivalent increase magnitude electrochemical change may result without having smaller thus being more favorable.