On the Role of MoSe2 in Promoting Persulfate Activation by Fe-Based Catalysts: Dual Redox Cycles and Performance and Mechanism of Efficient Phenol Degradation in Water

The recalcitrance and biological toxicity of phenolic pollutants pose a serious threat to the safety of aquatic environments, and developing efficient and stable catalytic degradation technologies is a key research focus in the current environmental field. In this study, a composite material (MSN) of NH2-MIL-101(Fe) modified by MoSe2 nanosheets was constructed via a one-step composite strategy, aiming to address the bottlenecks of low Fe3+/Fe2+ cycling efficiency and iron ion leaching in traditional Fe-based MOFs when activating peroxymonosulfate (PMS). Characterization results showed that MoSe2 nanosheets were uniformly dispersed on the surface of NH2-MIL-101(Fe), and strong electronic interactions existed between them, which significantly optimized the electronic environment of active sites. MSN-3 exhibited excellent performance in activating PMS for phenol degradation: the degradation rate reached 90% within 30 min, with a k = 0.073 min−1, which was much higher than that of other systems. It also showed good structural stability and cyclic regeneration ability. Mechanistic studies confirmed that the core active species in the MSN-3/PMS system are 1O2, •SO4− and •OH. The two-dimensional layered structure of MoSe2 can serve as an efficient electron transport bridge to promote Fe3+/Fe2+ cycling; amino modification further optimizes the electron density of Fe active centers. The two synergistically construct a dual redox cycle of Fe3+/Fe2+ and Mo4+/Mo6+, significantly enhancing PMS activation efficiency and 1O2 production. This study provides a new strategy for designing Fe-MOFs-based PMS activation catalysts and also offers technical support for the practical treatment of recalcitrant organic pollutants in water.