Microenvironment modulation of Fe single atoms in porous g-C3N4 by introducing −SOx groups for enhanced photo-Fenton reactions

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Heterogeneous photo-Fenton reactions based on hydrogen peroxide (H2O2) activation exhibit great potential in the treatment of organic wastewater. For developing efficient photo-Fenton catalysts, a fundamental investigation into the specific catalytic sites and the reaction mechanism is highly desired. Herein, a novel photo-Fenton catalyst (Fe1/CN-SOx) was constructed by synchronously anchoring Fe single atoms (SAs) and oxidized sulfur (−SOx) groups into porous graphitic carbon nitride (g-C3N4). The presence of trace −SOx groups altered the local configuration of g-C3N4 and optimized the coordination microenvironment of Fe SAs, thereby modulating the electronic structures of catalytic sites in favor of H2O2 activation. The cooperation between Fe SAs and the neighboring C atoms bonded with −SOx (C-SOx) enhanced the adsorption and cleavage of H2O2. The photoinduced charge carriers further accelerated Fe2+/Fe3+ redox cycles and hydroxyl radical (•OH) production, achieving an efficient photo-Fenton synergistic catalysis for continuous degradation of organic contaminants. The Fe1/CN-SOx catalyst also exhibited excellent anti-interference performance in diverse aquatic systems and good long-term stability, indicating its great potential for applications in water treatment. This study provides an in-depth insight into the optimal fabrication of single-atom active sites by modulating the local structures of support materials, aiming to enhance photo-Fenton reactions.