Novel MIL-53(Fe)/SnS2 Z-scheme heterojunction as photoactivator of peroxymonosulfate for efficient degradation of RhB

The construction of heterojunction photocatalysts with high efficiency for activating peroxymonosulfate (PMS) to degrade organic pollutants has aroused wide concern. Herein, a novel MIL-53(Fe)/SnS₂ Z-scheme heterojunction photocatalyst was successfully prepared by solvothermal method, which was used for the degradation of rhodamine B (RhB) in the catalyst/PMS system under visible light irradiation. The results showed that the MIL-53(Fe)/SnS₂-3 % (3 % is the mass ratio of SnS₂ to MIL-53(Fe)) displayed the highest activity reaching a RhB (10 mg/L, 100 mL) removal rate of 85.6 % within 60 min with catalyst and PMS dosage of 0.1 and 0.1 g/L, respectively. The corresponding reaction rate constant exceeded that of MIL-53(Fe) and SnS₂ by a factor of 1.39 and 6.39 times, respectively. The enhanced performance of MIL-53(Fe)/SnS₂/PMS system can be attributed to the Z-scheme heterojunction formed between MIL-53(Fe) and SnS₂, which inhibits the recombination of photogenerated electron-hole pairs. The PMS activation mechanism by MIL-53(Fe)/SnS₂ was proposed based on the detailed catalyst characterization, degradation efficiency tests, electron paramagnetic resonance and radical quenching experiments. Furthermore, the MIL-53(Fe)/SnS₂ exhibited good stability and suitability for different environmental conditions. This work provides a valuable guide for the development of Fe-based metal-organic frameworks (MOF) composites for photoactivation of PMS to remove organic dyes in aquatic environment.