Design Strategies for Boosting the Activity and Stability of CoO x ‐Based Electrocatalysts for Acidic Oxygen Evolution Reaction

ABSTRACT Proton exchange membrane (PEM) water electrolysis requires cost‐effective and stable electrocatalysts for acidic oxygen evolution reaction (OER). Cobalt‐based oxides (CoO x ) are among the most promising nonnoble candidates but suffer from the inherent trade‐off between activity and stability. Breaking this trade‐off demands innovative design paradigms. To this end, a timely and systematic understanding on the existing design strategies of enhancing the activity and stability of CoO x ‐based electrocatalysts for acidic OER is highly desirable. This review comprehensively summarizes the recent advancements in this field, with a focus on bridging design principles to the optimization of intrinsic properties of catalysts. First, the strategies for enhancing the activity are reviewed, including engineering crystalline structure, regulating surface oxidation states, modulating the redox properties of active sites, manipulating reaction pathways, and synergistically optimizing the reaction kinetics and charge transport. Then, the strategies for improving the stability are described, including strengthening the catalyst‐substrate interactions, coating catalyst with protective layers, designing oxide composites, regulating electronic structure, and optimizing local reaction microenvironments. Finally, the challenges and future opportunities for advancing CoO x ‐based electrocatalysts in acidic OER are discussed. These insights are expected to provide guidance for the development of CoO x ‐based electrocatalysts with both exceptional activity and stability for acidic OER.