Generation of FeIV =O and its Contribution to Fenton-Like Reactions on a Single-Atom Iron-N-C Catalyst.

ABSTRACT

Generating FeIV =O on single-atom catalysts by Fenton-like reaction has been established for water treatment; however, the FeIV =O generation pathway and oxidation behavior remain obscure. Employing an Fe-N-C catalyst with a typical Fe-N4 moiety to activate peroxymonosulfate (PMS), we demonstrate that generating FeIV =O is mediated by an Fe-N-C-PMS* complex-a well-recognized nonradical species for induction of electron-transfer oxidation-and we determined that adjacent Fe sites with a specific Fe1 -Fe1 distance are required. After the Fe atoms with an Fe1 -Fe1 distance <4 Šare PMS-saturated, Fe-N-C-PMS* formed on Fe sites with an Fe1 -Fe1 distance of 4-5 Šcan coordinate with the adjacent FeII -N4 , forming an inter-complex with enhanced charge transfer to produce FeIV =O. FeIV =O enables the Fenton-like system to efficiently oxidize various pollutants in a substrate-specific, pH-tolerant, and sustainable manner, where its prominent contribution manifests for pollutants with higher one-electron oxidation potential.