Defect-tailored MoS2 for superior Fenton-like catalysis: The synergistic reactive sites of 1T phase and sulfur vacancy in electron transfer and radical generation

Abstract

Pollutants removal by Fenton-like catalysis is of considerable interest, and the solid catalyst play governing roles. Two-dimensional MoS2 can activate peroxymonosulfate (PMS) for radical-mediated catalysis via metallic 1T phase and/or crystal defects (i.e., sulfur vacancy). Herein, we explored the significant synergism between defective sulfur vacancy and metallic 1T rather than semiconducting 2H phase for Fenton-like catalysis on MoS2. This synergism was substrate-dependent during MoS2 preparation. A series of sulfur-defected 1T-MoS2 were prepared by H2O2 oxidation, drastic structural but no morphological changes were measured. The defect-tailored 1T-MoS2 exhibited a superior Fenton-like reactivity toward PMS activation and pollutant degradation in various water matrices. A 10.0 mg·L-1 of aqueous phenol was completely degraded in one hour, and the corresponding pseudo-first order reaction constant increased more than 12 times after defect engineering. No synergistic effect was measured between sulfur vacancy and semiconducting 2H phase on defective 2H-MoS2. Radical-mediated reaction mechanism was identified by ESR, scavenger inhibiting, spectroscopic analysis and electrochemical measurements. Electron transfer was accelerated within metallic 1T phase to favor PMS activation and pollutant degradation on defective sulfur vacancies serving as surface reactive sites. Our findings provided fundamental insights into PMS activation on sulfur vacancy promoted by 1T-MoS2 in Fenton-like catalysis for water purification.