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

Abstract

• Defective MoS 2 enhanced PCA removal of Fe 3+ /PS system compared with pristine MoS 2 . • S defects in MoS 2 facilitated the cycle of Fe 3+ /Fe 2+ to enhance PCA degradation. • S defects in MoS 2 increased the electron density around Mo. • S defects in MoS 2 enhanced the adsorption of Fe 3+ . 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 Fe 2+ and little activation capability of Fe 3+ limit the broad applications of Fe 2+ (or Fe 3+ ) activated PS system in practical applications. In this work, taking molybdenum disulfide (MoS 2 ) as the co-catalyst in Fe 3+ /PS system, we report a strongly enhanced persulfate activation efficiency of Fe 3+ /PS system by engineering S defects in MoS 2 . The combination of experiments and density functional theory (DFT) calculation demonstrate that S defects in MoS 2 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 Fe 3+ in Fe 3+ /PS system is reduced into Fe 2+ by MoS 2 with S defects, resulting in more reactive oxygen species generated. Furthermore, S defects promote the adsorption of Fe 3+ on the MoS 2 surface, which further enhance the activating performance for PS through promoting to form cycle of Fe 3+ /Fe 2+ . This work provides a new strategy for improving co-catalytic properties of MoS 2 and expands the application of Fe 3+ /PS system for contaminants remediation.