Advances in Single-Atom Catalysts for Acidic and Alkaline Oxygen Evolution Reactions: Mechanisms and Applications.

Water electrolysis for hydrogen production has become an industrial focus in the era of green chemistry due to its high purity of hydrogen production and environmentally friendly, efficient process. As the half reaction of water splitting at the anode, the oxygen evolution reaction (OER) features a complex and sluggish process that restricts the efficiency of water splitting. The mechanism of OER varies with different electrolytes. Single-atom catalysts (SACs) have become a research hotspot due to their advantages, such as nearly 100% atomic utilization efficiency and abundant, uniform active sites. Through structural optimization and coordination environment regulation, SACs can effectively enhance the efficiency of OER. This review comprehensively summarizes the OER mechanisms under both acidic and alkaline conditions, systematically compiles the performance and applications of precious-metal and nonprecious-metal SACs in OER, and provides mechanistic insights through density functional theory calculations. Finally, it provides an outlook on the research prospects of single-atom electrocatalysts, offering references and guidance for the preparation of higher-performance single-atom electrocatalysts.