Single Fe atoms confined in two-dimensional MoS2 for sulfite activation: A biomimetic approach towards efficient radical generation

[Display omitted] •Single Fe atoms confined in two-dimensional MoS2 mimic sulfite oxidase enzyme.•MoS2 not only consists of Mo catalytic sites but also provides the support for Fe catalytic sites.•Dual catalytic sites play collaboratively to obtain high reactivity for sulfite activation.•2D catalyst allows interpretation of catalytic performances using theoretical calculation. Sulfite has been recently recognized as a source of radicals for oxysulfur radical-based advanced oxidation process due to its low cost and low toxicity. Inspired by sulfite oxidase enzyme, we demonstrate single Fe atoms confined in two-dimensional MoS2 nanosheets (FexMo1-xS2) as highly reactive catalysts for heterogeneous activation of sulfite, thereby promoting efficient oxidative degradation of propranolol in water. Highest propranolol degradation efficiency of ∼90 % was observed at pH 4.0. The Fe or Mo sites of FexMo1-xS2 activate sulfite via the Fe2+/Fe3+ or Mo4+/Mo5+/Mo6+ redox cycle. More importantly, the synergistic catalysis involving the Fe and Mo sites play an essential role. SO5− is the major radical responsible for propranolol degradation with the 2nd-order rate constant of (1.1 ± 0.6)×107 M−1 s−1. Furthermore, the FexMo1-xS2/sulfite system is capable of degrading a wide range of recalcitrant organic pollutants and operating in a real water environment, suggesting its great potential in practical water treatment applications.