Ultralow-peroxymonosulfate-initiated dissolved oxygen activation for micropollutant decomposition by an asymmetric single-site metal (Fe-N2O1S1) catalyst

A novel Fe-N 2 O 1 S 1 single-atom catalyst (Fe SA -NS-Ti 3 C 2 T x ) was developed for dual activation of ultra-low concentration peroxymonosulfate (PMS) and dissolved oxygen in wastewater treatment. The catalyst was synthesized via a multivariate heteroatom doping strategy using transition metal salt solution and thiourea on Ti 3 C 2 T x . Under 0.1 mM PMS, the Fe SA -NS-Ti 3 C 2 T x achieved 100 % acetaminophen (20 μM) removal within 6 min, with a K c mp of 889.77 min −1 g −2 L 2 and a turnover frequency over two orders of magnitude higher than homogeneous Fe 2+ /Fe 3+ and iron oxides. Mechanistic analysis and theoretical calculations showed that the asymmetric Fe-N 2 O 1 S 1 site optimizes the generation of ·O 2 − and 1 O 2 , efficiently removing ACE through deacetylation and electrophilic attack on the benzene ring. In the long-term tests, the iron leaching of the high-density catalytic bed is negligible, ensuring environmental safety. This study highlights a cost-effective and scalable strategy to advance PMS-based advanced oxidation technologies in wastewater treatment.