Conversion of peroxymonosulfate to singlet oxygen by single-atom catalysts for water remediation

Peroxymonosulfate (PMS)-based advanced oxidation processes to produce reactive oxygen species (ROS) have been developed for water treatment. For actual wastewater, high-concentration inorganic anions and natural organic matter can react with reactive radicals to reduce utilization efficiency of oxidants. The non-radical degradation pathway initiated by singlet oxygen (1O2) can replace the oxidation process dominated by free radicals. The catalysts (such as single atom catalysts, SACs) with excellent catalytic performance and high selectivity are developed to activate PMS to generate 1O2. In this review, we firstly summarize recent developments in preparation and characterization of SACs. Then, the fundamentals of highly selective conversation PMS-to-1O2 by SACs, and the degradation mechanism of contaminants by 1O2 are discussed, respectively. Subsequently, we introduce the applications of advanced SACs catalyzed PMS-to-1O2 for degrading pollutants in wastewater. Furthermore, SACs are employed to construct the reactor for treating the flowing wastewater. Finally, we make some prospects for this emerging area in the future.