Discovery of the role of MoS2 in the promotion of peroxymonosulfate activation for the degradation of sulfamethoxazole in Fe/CN

The widespread application of antibiotics can lead to the growth of numerous antibiotic-resistant bacteria in the ecosystem. Electron-rich iron sites in iron-based catalysts are considered to be the main sites for activation of peroxymonosulfate (PMS), but the restricted Fe^2 +/Fe³⁺ cycling inhibits the catalytic performance of iron-based catalysts. To address the above challenges, we prepared Fe/CN@MoS₂-X (X represents the Fe/Mo mass ratio) samples with dual active sites by anchoring MoS₂ nanosheets on Fe/CN nanocomposite catalysts. The inclusion of MoS₂ not only promotes Fe²⁺/Fe³⁺ cycling and accelerates electron transfer, thus improving the catalytic performance, but enhances environmental tolerance (wide pH application range 3–9 and resistance to ionic interference). The degradation rate of sulfamethoxazole (SMX) by the Fe/CN@MoS₂-1/PMS system (0.15 min⁻¹) was 3.76 times higher than that of the Fe/CN/PMS system (0.04 min⁻¹). Moreover, the Fe/CN@MoS₂-1/PMS system exhibited excellent stability and regeneration ability, with the removal rate remaining stable at 92 % after 5 cycles. Quenching experiments and EPR tests demonstrated that •OH, SO₄^-•, O₂^-• and ¹O₂ in the Fe/CN@MoS₂-1/PMS system were all involved in the SMX degradation. Finally, the C-N, N-O, S-N, C-O and C-S bonds of SMX are readily attacked by reactive actives, resulting in the generation of non-toxic intermediates in the system. This work shows that Fe/CN@MoS₂ presents satisfactory versatility, recyclability and stability, as well as providing new perspectives to address Fe²⁺/Fe³⁺ cycling in iron-based catalysts.