Atomically Dispersed Fe‐Modified SnS for Sn‐Centered Peroxymonosulfate Activation Toward Acetaminophen Degradation

SnS is a low‐cost and environmentally benign semiconductor for photocatalysis and piezocatalysis, but its direct use for peroxymonosulfate (PMS) activation remains limited. Here, we develop a facile Fe substitution strategy to construct atomically dispersed Fe‒S in SnS nanostructures (Fe‐SnS) for efficient PMS activation. The catalytic activity shows a volcano‐shaped dependence on Fe incorporation, with 5% Fe‐SnS (Fe/Sn molar ratio of 4.63%) giving the optimal performance, achieving efficient acetaminophen (APAP) removal with a rate constant of 1.23 min ‒1 , which is 3.84 and 176‐fold higher than those of SnS and commercial SnS, respectively. In situ X‐ray absorption spectroscopy reveals a site‐dependent activation mechanism in which Sn sites directly coordinate with O in PMS. Density functional theory calculations further show that Fe incorporation induces local electronic redistribution around neighboring Sn sites and enhances the Sn–PMS interfacial interaction. Fe incorporation also attenuates the negative surface charge of SnS, further facilitating PMS interaction. Mechanism studies revealed that APAP degradation proceeds via sulfate and hydroxyl radical‐dominated pathway. These findings clarify the distinct roles of host Sn and atomically dispersed Fe sites in PMS activation.