Recent advances and challenges in single-atom catalysts for proton exchange membrane water electrolysis

Hydrogen energy represents a promising alternative to fossil fuels, with the potential to facilitate sustainable development in the future. Proton exchange membrane water electrolysis (PEMWE) technology can produce green hydrogen (H 2 ) at scale and with high purity, offering an environmentally benign solution. However, the advancement of PEMWE is currently restricted by challenges such as the sluggish kinetics of anode materials during the oxygen evolution reaction (OER) and high cost. Single-atom catalysts (SACs) possess high atomic utilization efficiency of loading metals with high mass activity, making them particularly promising applications in PEMWE. Additionally, the catalytic properties of SACs can be precisely tailored through specific interactions between the support and the active sites. This review elucidates the fundamental principles of OER and PEMWE, highlighting the unique advantages of SACs in the anodic reactions of PEMWE. Subsequently, we summarize recent research advances in the application of SACs within PEMWE and discuss essential characterization techniques for investigating the structure and mechanisms of SACs in OER. Finally, we provide a comprehensive overview of the current state of this field and outline prospective directions for future development.