Dual Anchoring Strategy for Single-Atom Fe Catalysts: Insights into 1O2-Driven Oxidation of Organic Contaminants

Single-atom catalysts (SACs), known for their maximized atom utilization and unique electronic structures, were widely utilized in Fenton-like reactions for organic contaminant removal. Due to prolonged use or complex reaction environments, the active sites were prone to oxidation, agglomeration, or carrier degradation, leading to deactivation. Herein, a single-site Fe catalyst anchored on N-doped carbon nanotubes (Fe SA -N-CNT) was successfully synthesized by a dual anchoring strategy of EDTA and melamine. Fe SA -N-CNT catalyst exhibited an outstanding performance in peroxymonosulfate (PMS) activation, achieving more than 90% removal of sulfasalazine (SSZ) within 10   min. Combined experimental results and density functional theory (DFT) calculations revealed that the Fe-pyridine N 4 coordination sites and the adjacent carbon atoms (sub-C) served as dual active sites, facilitating a singlet oxygen ( 1 O 2 )-dominated oxidation of SSZ. Fe-N 4 sites could promote the formation of SO 5 •− , which subsequently generated 1 O 2 , while the sub-C sites contributed to the generation of superoxide anion radical (O 2 •− ), a precursor of 1 O 2 . The present study provided a novel strategy for synthesizing highly active SACs and deeper insights into the mechanisms of reactive oxygen species (ROS) generation within SACs/PMS systems for effective organic pollutant decontamination.