Heterogeneous catalytic oxidation activity is limited by low radical utilization owing to the ultrashort lifetimes and nonselective consumption of radicals. Here, a template-free preassembly strategy was used to construct a single Fe atom catalyst with highly accessible Fe-N6 active sites for peroxymonosulfate (PMS) activation, and the catalyst achieved excellent pollutant degradation (0.364 s−1 g−2). High-valent iron–oxo species, ≡Fe(IV)=O, with long lifetimes and oxidation selectivity was verified to be the main active species. The ≡Fe(IV)=O mediated oxidation process exhibits 97.2% average PMS utilization rate which is hundreds of times higher than other PMS activators. Theoretical calculations indicated that orbital symmetry matching spontaneously drives ≡Fe(IV)=O formation. ≡Fe(IV)=O is reversibly reduced to ≡Fe–N6 by electron donor, which is beneficial for a fast and sustainable Fe–N6 to ≡Fe(IV)=O cycle. Fe–N6 active sites are highly stable which maintain 100% removal efficiency after 5867 BV in continuous filtration test.

High-valent iron–oxo species mediated cyclic oxidation through single-atom ≡Fe–N6 sites with high peroxymonosulfate utilization rate

ACS Spring 2022

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