Plasma-Engineered Oxygen Vacancies Tailor Reaction Pathways for Stable High-Activity Acidic Oxygen Evolution

Abstract Developing acid-stable and efficient nonprecious metal electrocatalysts is crucial for scalable hydrogen production via proton exchange membrane water electrolysis. However, such catalysts generally suffer from a trade-off between long-term stability and high catalytic activity. Here, we present a plasma-induced oxygen vacancy strategy to activate Co3O4–x catalysts for the acidic oxygen evolution reaction. The optimized N2-Co3O4–x catalyst operates through an oxygen-vacancy-optimized AEM pathway that suppresses the unstable LOM pathway and lowers the *OOH formation barrier, thereby boosting catalytic activity with improved stability. As a result, the catalyst delivers overpotentials of only 274 mV at 10 mA cm–2 and 415 mV at 1000 mA cm–2 in 0.5 M H2SO4, while sustaining robust durability for over 100 h at 20 mA cm–2. Crucially, we demonstrate that the surface oxygen vacancy proportion governs reaction pathways. By elucidating plasma mechanisms governing defect generation, we established a quantitative plasma kinetics framework that enables vacancy tailoring and controlled regulation of reaction pathways. This work establishes plasma-induced defect engineering as a promising paradigm to break the activity-stability trade-off through reaction pathway tailoring, advancing the large-scale application of hydrogen energy.