Interlayer single-atomic Fe−N4 sites on carbon-rich graphitic carbon nitride for notably enhanced photo-Fenton-like catalytic oxidation processes towards recalcitrant organic micropollutants

Glucose-assisted supramolecule self-assembly of melamine and cyanuric acid in the presence of Fe(NO3)3 combined with thermal polymerization is designed to fabricate C-rich g-C3N4-embedded interlayer single-atomic Fe−N4 sites catalyst (Fe1/C-CN). Fe1/C-CN exhibits outstanding photo-Fenton-like catalytic oxidation activity towards typical recalcitrant organic micropollutants. For example, the pseudo-first-order kinetic constant of Fe1/C-CN photo-Fenton-like system is 7.5 and 21.1 times higher than Fe1/C-CN photocatalysis and Fenton-like systems in degradation of p-nitrophenol, and TOC removal efficiency reaches up to 100% after reaction proceeds for 4 h. Mechanism studies reveal that synergy of maximum Fe atom utilization efficiency and boosted photoexcited charge separation dynamics accelerates regeneration of ≡Fe(II) and efficient H2O2 activation of Fe1/C-CN, leading to plentiful active oxygen species for deep oxidation of organic micropollutants. Fe1/C-CN also shows a robust reusability in long-term remediation of organic micropollutants, attributing to interlayer Fe−N coordination interactions for preventing single Fe atoms from agglomeration and leaching to reaction media.