Halogen-Driven Electronic Modulation of Single-Atom Fe Sites for Universal Non-Radical Catalysis.
basic_science · Level V
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- Record sourced from PubMed, PMID 42246687.
- Also identified by DOI 10.1002/adma.73634.
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Abstract
Selective and matrix-tolerant advanced oxidation processes (AOPs) are essential for treating real waters. Iodine-polarized Fe-N<sub>4</sub> single-atom sites in N-doped carbon (Fe-NI-C) are engineered to molecularly adsorb peroxymonosulfate (PMS) and lower its activation barrier, enabling ultrafast, non-radical phenol oxidation. Fe-NI-C/PMS achieves complete removal within 2 min (k<sub>obs</sub> = 4.098 min<sup>-1</sup>, 195-fold over N-C) with 71.2% total organic carbon abatement, maintaining near-quantitative activity from pH 3-11 and in tap, river, and seawater. Electrochemical, quenching, and EPR assays decipher an electron-transfer-to-singlet-oxygen cascade (ETP → <sup>1</sup>O<sub>2</sub>): a surface Fe-PMS* adduct triggers interfacial electron flux, producing <sup>1</sup>O<sub>2</sub> as the selective oxidant while suppressing free-radical and matrix scavenging. Spin-polarized density functional theory (DFT) shows iodine upshifts the Fe 3d band toward E_F, strengthens Fe 3d-PMS σ* coupling, stabilizes side-on O-O adsorption (E<sub>ads</sub> = -1.89 eV), and lowers the transition-state barrier to 0.35 eV. Activity follows I > Br > Cl > F, consistent with dopant polarizability and Bader charge transfer (up to 0.88 e). Intrinsic metrics (turnover frequency, TOF; K<sub>ac</sub>) confirm site-level acceleration beyond textural effects. These results establish soft-ligand electronic polarization of Fe-N<sub>4</sub> as a programmable route to radical-free, selective, and matrix-robust PMS activation for advanced water purification.