Mechanical insight into direct singlet oxygen generation pathway: The significance of Co-O-X bond formation anchored by cobalt single atoms on mesoporous oxides

The understanding of how single atoms anchoring on oxides contribute to high-activity catalysis in the sulfate radical-advanced oxidation process (SR-AOP) remains obscure. Here we presented a new strategy for regulating singlet oxygen (¹O₂) generation in peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) by engineering the Co-O-X active sites on oxide supports in this study. The Co single atoms supported on mesoporous oxides (Co_SA-XO₂) were first successfully developed using a modified sol–gel solvent vaporization self-assembly method. We found that Co_SA-XO₂ catalysts served as efficient PMS activators for pollutant decomposition over a wide pH range. Notably, Co_SA-TiO₂ exhibited exceptional performance, achieving nearly 100% removal of sulfasalazine (SSZ) within 10 min. Furthermore, evidenced by experimental results and density functional theory (DFT) calculations, ¹O₂ was confirmed to be predominately active oxidizing species by the unique Co-O-X bonds for activating PMS in Co_SA-XO₂/PMS system, resulting in an excellent pollution degradation. This study provides valuable insights into the construction of highly loaded single-atom catalysts using oxide substrates in the PMS-AOP system, along with the mechanism of regulating reactive oxygen species (ROS) formation through interfacial bonding between active metal and support.