Novel Co-MOF/GO triggered peroxymonosulfate activation: Insight into singlet oxygen generation mechanism from peroxymonosulfate self-decomposition and secondary radical conversion

Peroxymonosulfate (PMS)-triggered non-radical pathways have potential for environmental application due to the high activity and pH tolerance of singlet oxygen (1O2). However, the mechanism of 1O2 generation remains unclear. Herein, new insights into 1O2 generation are discussed based on the postulated precursors of PMS, DO, O2–, SO4−, and OH with Co-MOF/GO catalyst. According to experimental results and theoretical calculation, Co (II) and Co (III) were identified as dominant active sites for PMS attachment, leading to the simultaneous breakage of S-O and O-O bonds and the generation of SO4−, OH, and 1O2. SO4− and OH were critical precursors for 1O2 generation, while PMS self-decomposition had a small contribution. DO and O2– acted more likely as quenchers than vital precursors of 1O2. Results provide in-depth understanding of the mechanism of 1O2 generation to broaden the application prospects of PMS oxidation technology.