Surface Reconstruction Activates Bridge Sites of Rutile IrO2(110) for Oxygen Evolution Reaction

IrO2 is the state-of-the-art catalyst for oxygen evolution reaction (OER) in acid. Previous theoretical investigations are largely based on the (110) surface, with undercoordinated Ircus sites being considered as active centers under reaction conditions, whereas coordinated Irbr sites are considered spectators. Using a combination of density functional theory and ab initio molecular dynamics, we demonstrate that the Irbr sites reconstruct under anodic polarization leading to the formation of single-atom catalyst (SAC)-like centers. These SAC sites exhibit higher activity for OER than Ircus sites and are identified as durable under anodic polarization using a stability analysis based on a Born-Haber cycle. This work provides a framework for understanding how surface reconstruction fundamentally alters the catalytic function of known oxide surfaces by transforming spectator sites into primary active centers for energy conversion and storage.