Enhancing co-catalysis of MoS2 for persulfate activation in Fe3+-based advanced oxidation processes via defect engineering

Advanced oxidation processes (AOPs) based on persulfate (PS) has attracted great attention because of its outstanding performance for decomposing chlorinated aromatic hydrocarbons in wastewater. While Fe-based materials can effectively activate PS and are environment-friendly, the low stability of Fe2+ and little activation capability of Fe3+ limit the broad applications of Fe2+ (or Fe3+) activated PS system in practical applications. In this work, taking molybdenum disulfide (MoS2) as the co-catalyst in Fe3+/PS system, we report a strongly enhanced persulfate activation efficiency of Fe3+/PS system by engineering S defects in MoS2. The combination of experiments and density functional theory (DFT) calculation demonstrate that S defects in MoS2 modify the surface charge distribution, leading to the formation of an electron deficient center near S defect and increasing the electron density near Mo site. As a result, more Fe3+ in Fe3+/PS system is reduced into Fe2+ by MoS2 with S defects, resulting in more reactive oxygen species generated. Furthermore, S defects promote the adsorption of Fe3+ on the MoS2 surface, which further enhance the activating performance for PS through promoting to form cycle of Fe3+/Fe2+. This work provides a new strategy for improving co-catalytic properties of MoS2 and expands the application of Fe3+/PS system for contaminants remediation.