Shifting Oxygen Evolution Reaction Pathway via Activating Lattice Oxygen in Layered Perovskite Oxide

Abstract Developing high‐performance oxygen evolution reaction (OER) catalysts are critical for the practical application of many electrochemical energy devices. In this study, taking layered perovskite oxide thin films as the model system, it is demonstrated that the OER pathway can be effectively shifted by activating lattice oxygen, leading to strongly enhanced intrinsic activity. The OER performance of Ruddlesden‐Popper (RP)‐phase cobaltite is significantly enhanced as Sr doping at the A site increases, which is attributed to the shift of the reaction pathway from adsorbate evolution mechanism (AEM) to lattice oxygen‐mediated mechanism (LOM). Advanced spectroscopic techniques and density functional theory calculations reveal that the Sr dopant effectively facilitates oxygen ligand hole formation, charge transfer from the oxygen sites, and the formation and migration of oxygen vacancy, hence promoting lattice oxygen to participate in surface reactions. The results provide critical insight into the role of oxygen activity and offer a potential way for constructing highly active electrocatalysts.