The mechanistic difference of 1T-2H MoS2 homojunctions in persulfates activation: Structure-dependent oxidation pathways

Two-dimensional layered MoS2 recently demonstrates great potentials in water purification via adsorption and catalysis. The structure-catalysis relationship of MoS2 has not been well addressed. Herein, we investigated the mechanistic difference of 1 T-2H MoS2 homojunctions in catalytic activation of peroxymonosulfate (PMS) and peroxydisulfate (PDS) for degrading butyl paraben (BPB). PMS/1 T-2H MoS2 attains higher performance in BPB removal compared to PDS/1 T-2H MoS2. 1 T phase in MoS2 primarily contributed to PMS activation to produce SO4−, OH and 1O2, while the defects in MoS2 coordinated the PDS activation to generate OH, 1O2 and O2−. Nevertheless, OH-induced BPB removal was the top priority for PMS/1 T-2H MoS2 and PDS/1 T-2H MoS2. The different activation pathways and reactive species resulted in the varying BPB removal, by-product distributions and toxicity. This work provides new insights into the different functions of MoS2 in persulfates activation and the guidance in rational design of oxidant-oriented MoS2 composites for sewage purification.