Oxygen-Redox in Perovskite Oxide Catalysts for Oxygen Evolution Reaction

Perovskite oxides with formula ABO₃ are a promising group of materials for numerous electrochemical reactions. In recent years, the reaction mechanism based on metal-centred redox faces challenging as it leads to pH independent activity for reaction such as oxygen evolution reaction (OER). However, several cases have shown that under various pH values oxide-based electrocatalysts can be quite different. Therefore, the current metal-centered theory needs revision. The oxygen-centred redox reaction is believed to be key for explaining such phenomena and be implemented. To exam this, we used LaCo_xFe_1-xO₃ and doped with different P atoms as OER catalysts, which show improved catalytic activity and stability. Using several in-situ surface-sensitive synchrotron X-ray scattering and spectroscopy techniques, we exclude the metal-redox on these materials. In contrast, using soft X-ray absorption spectroscopy on oxygen K-edge, we identify the significant differences from these materials and believe the electronic structure of oxygen p-band is responsive for their OER activity.