Deciphering Cationic and Anionic Overoxidation: Key Insights into the Intrinsic Structural Degradation of Catalysts

Abstract Proton exchange membrane water electrolyzer (PEMWE) technology holds tremendous promise for large‐scale green hydrogen production. However, its widespread application faces significant constraints due to the limited lifespan of the oxygen evolution reaction (OER) catalyst in highly acidic and oxidative operating environments. Therefore, a comprehensive understanding of the catalyst's structural degradation mechanism is imperative for the rational design of high‐performance acidic catalysts. In this review, the essence of the structural degradation of catalysts: and irreversible cationic and anionic overoxidation is initially unveiled. This is followed by an in‐depth exploration of their intricate relationship with the adsorbate evolution mechanism (AEM) and lattice oxygen oxidation mechanism (LOM). Then, state‐of‐the‐art characterization techniques for cationic and anionic overoxidation analysis are introduced. Subsequently, 4 cutting‐edge catalyst antioxidation strategies, including heterostructure engineering, doping strategy, nanostructuring, and phase engineering are systematically discussed, aiming to reveal their intrinsic factors for effectively inhibiting catalyst overoxidation. Finally, the remaining challenges and prospective insights into catalysts for PEMWE are delineated. The overarching goal of this review is to facilitate a fundamental understanding of catalyst structural degradation mechanisms and provide principal guidelines for the rational design of robust acidic OER catalysts.