Almost 100 % Peroxymonosulfate Conversion to Singlet Oxygen on Single-Atom CoN Sites.

Single-atom CoN active sites have demonstrated excellent efficiency in peroxymonosulfate activation. However, the identification of CoN active sites and the detailed singlet oxygen generation mechanism in peroxymonosulfate activation remains ambiguous. We demonstrate a strategy to regulate the generation of reactive oxygen species by atomically dispersed cobalt anchored on nitrogen-doped carbon. As indicated by experiment and DFT calculations, CoN was the active site and singlet oxygen was the predominant reactive oxygen species with a proportion of 98.89 %. Spontaneous dissociation of adsorbed peroxymonosulfate on the CoN active sites was energetically unfavorable because of the weakly positive Co atoms and CoN coordination, which directed PMS oxidation by a non-radical pathway and with simultaneous singlet oxygen generation. The generated singlet oxygen degraded several organic pollutants with high efficiency across a broad pH range.