Non‐Noble‐Metal‐Based Electrocatalysts for Acidic Oxygen Evolution Reaction: Recent Progress, Challenges, and Perspectives

Abstract The oxygen evolution reaction (OER) plays a pivotal role in diverse renewable energy storage and conversion technologies, including water electrolysis, electrochemical CO 2 reduction, nitrogen fixation, and metal‐air batteries. Among various water electrolysis techniques, proton exchange membrane (PEM)‐based water electrolysis devices offer numerous advantages, including high current densities, exceptional chemical stability, excellent proton conductivity, and high‐purity H 2 . Nevertheless, the prohibitive cost associated with Ir/Ru‐based OER electrocatalysts poses a significant barrier to the broad‐scale application of PEM‐based water splitting. Consequently, it is crucial to advance the development of non‐noble metal OER catalysis substance with high acid‐activity and stability, thereby fostering their widespread integration into PEM water electrolyzers (PEMWEs). In this review, a comprehensive analysis of the acidic OER mechanism, encompassing the adsorbate evolution mechanism (AEM), lattice oxygen mechanism (LOM) and oxide path mechanism (OPM) is offered. Subsequently, a systematic summary of recently reported noble‐metal‐free catalysts including transition metal‐based, carbon‐based and other types of catalysts is provided. Additionally, a comprehensive compilation of in situ/operando characterization techniques is provided, serving as invaluable tools for furnishing experimental evidence to comprehend the catalytic mechanism. Finally, the present challenges and future research directions concerning precious‐metal‐free acidic OER are comprehensively summarized and discussed in this review.