Revisiting the Heterogeneous Peroxymonosulfate Activation by MoS2: a Surface Mo–Peroxymonosulfate Complex as the Major Reactive Species

Heterogeneous peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) are under extensive investigation for their great potential in water remediation. The understanding of the PMS activation mechanism is crucial but still debatable. Here, we describe a thorough investigation of the mechanism involved in PMS activation by using molybdenum disulfide (MoS2) as a catalyst. This MoS2/PMS system exhibited intriguing target-dependent reactivity. Further comprehensive experimental results excluded the major contributions of various possible species, including HO•, SO4•–, O2•–, 1O2, homogeneous Mo(VI), and heterogeneous Mo(VI). We then proposed a surface ≡Mo–OOSO3– complex as the major reactive species, while SO4•– derived from the decomposition of ≡Mo–OOSO3– acted as the secondary reactive species for pollutant removal. This complex could oxidize pollutants through the oxygen-atom-transfer mechanism and perform both nucleophilic and electrophilic attacks. This work provides novel perspectives for the mechanistic understanding of heterogeneous PMS-based AOPs for water remediation.