MoS2 Nanosheets Anchored onto MIL-100(Fe)-Derived FeS2 as a Peroxymonosulfate Activator for Efficient Sulfamethoxazole Degradation: Insights into the Mechanism

By anchoring MoS2 nanosheets onto FeS2 derived from different MIL-100(Fe) precursors, a series of FeS2@MoS2-x samples featuring sulfur vacancies (SVs) were prepared as efficient peroxymono-sulfate (PMS) activators to degrade sulfamethoxazole (SMX) from aqueous solution. Benefiting from the strongly reductive sulfur species (S2- and S22-), enriched Mo(IV) sites, and abundant SVs, 40 mu M SMX was completely removed by the FeS2@MoS2-2/PMS system in 7 min (0.2 g/L FeS2@MoS2-2, 0.25 mM PMS). The kobs obtained by FeS2@MoS2-2 was 0.598 min-1, which was 5.8 and 51.1 times higher than that of FeS2 (0.103 min-1) and MoS2 (0.012 min-1), respectively. Quenching experiments, electron paramagnetic resonance (EPR) analysis, and 18O isotope labeling tests evidenced the involvement of radical (center dot OH, SO4 center dot-) and non-radical (1O2, FeIV = O) pathways in the FeS2@MoS2-2/PMS system, and MoS2 anchoring enormously enhanced the contribution of non-radicals to 45.5%. In addition, SVs possessed favorable affinity toward PMS and dissolved oxygen (DO), promoting continuous production of reactive active species. The degradation pathways of SMX were unveiled as well. The satisfactory recyclability, stability, and universality enabled FeS2@MoS2-2 to serve as a promising candidate for PMS activation. This study provides a novel strategy to construct sulfur vacancy-featuring Fe-based sulfide catalysts using MIL-100(Fe) as sacrificial templates for activating PMS to treat refractory organic-polluted water.

Automated summary

By anchoring MoS2 nanosheets onto FeS2 derived from different MIL-100(Fe) precursors, efficient FeS2@MoS2-x samples with sulfur vacancies were prepared for degrading sulfamethoxazole (SMX) from aqueous solution, demonstrating significant degradation performance.