Charge State Evolution in Electrocatalysts for Bridging the Activity–Stability Gap in Acidic Oxygen Evolution

ConspectusThe acidic oxygen evolution reaction (OER) is a critical component in industrial hydrogen production via proton exchange membrane water electrolysis (PEMWE). However, under the harsh operating conditions of strong acid and high potential, catalysts often reach high oxidation states to achieve high catalytic activity, which concomitantly accelerates the dissolution of active components and leads to structural degradation, making it challenging to simultaneously attain both high activity and long-term stability. Therefore, developing more precise strategies to regulate acidic OER catalysts to balance activity and stability is essential for advancing PEMWE technology.Notably, charge effects play a crucial role in regulating catalytic performance. This dependence arises not only from the intrinsic electronic structure of the catalysts but also from the dynamic generation, redistribution, and migration of charge during the reaction. This is particularly evident in the acidic OER, where under sustained high-potential conditions, active sites undergo continuous valence-state evolution, dynamic adsorption and desorption of intermediates, and both the interfacial double layer and the local coordination environment are subject to real-time change. In such a dynamic regime, design strategies based solely on static electronic structures or equilibrium properties often fail to predict or control catalytic behavior under practical operating conditions. Consequently, the systematic understanding and regulation of dynamic charge-state evolution is an essential step for balancing activity and stability in acidic OER.In this account, we focus on the dynamic regulation of charge states during operation and illustrate its central role in governing both the activity and stability of the acidic OER. First, we provide an overview and analysis of the fundamental characteristics of charge effects during the reaction, including: (i) the tunability of operational charge states, which enables adaptive response to electronic demands; (ii) the directionality of reaction-induced charge distribution, which governs the evolution of reaction pathways and local environments; (iii) the sustainability of charge-transferring and buffering capacity, which underpins long-term structural and performance stability. Then, based on our recent research advances in this field, we systematically outline the strategies for modulating these dynamic charge behaviors across multiple scales through active-site engineering, support engineering, and surface engineering. Furthermore, we summarize how in situ characterization, electrochemical analysis, and theoretical calculations are jointly employed to probe charge state evolution, and to correlate it with reaction pathway selection and stability. Finally, we discuss the limitations and emerging opportunities in dynamic charge regulation concerning in situ mechanism elucidation, cross-scale integration, and material system expansion. This account provides insights for designing acidic OER catalysts with charge evolution tailored to PEMWE operating conditions.