Unraveling the Oxygen Vacancy Site Mechanism of a Self-Assembly Hybrid Catalyst for Efficient Alkaline Water Oxidation

Exploring perovskite oxide electrocatalysts with high activity for the oxygen evolution reaction (OER) is of vital importance for various energy conversion processes. Although the materials proceeding a lattice oxygen-mediated mechanism-single metal site mechanism (LOM-SMSM) could break the inherent theoretical overpotential ceiling of the absorbent evolution mechanism (AEM), the fast surface remodeling and activity loss are still the huge obstacles hindering robust electrolysis. Herein, via delicately tuning the stoichiometry of precursor dosage, we reported a hybrid electrocatalyst consisting of self-assembled Ruddlesden–Popper and perovskite phases, which delivered attractive activity (overpotential at 280 mV at 10 mA/cm2) and durability over 120 h. As compared to the physically mixed counterparts, the self-configured electrocatalyst enjoyed a large amount of oxygen defects, which doubled the oxygen exchange rate. Quasi in situ X-ray photoelectron spectroscopy (XPS) further demonstrated the reversibility of these reactive oxygen defects (Vo.. ↔ Olattice2–) under OER working potentials. Further, collective differential electrochemical mass spectrometry (DEMS) and theoretical calculations revealed that AB0.8 passed through a more optimal reaction path of the lattice oxygen-mediated mechanism-oxygen vacancy site mechanism (LOM-OVSM) happening on interface tying RP and perovskite, further elaborating the unique stabilization mechanism. This work provides a rational recipe to develop a highly efficient catalyst for electrochemical oxidative reactions.