Z-Scheme CdS/Fe-MOF Heterojunctions Enabling Efficient Photo-Fenton Reactions through In Situ H2O2 Production

This work demonstrates the rational design of a Z-scheme CdS/Fe-MOF heterojunction for photo-Fenton processes utilizing in situ generated H2O2 under visible light. The photocatalysts were synthesized by depositing CdS nanoparticles onto MIL-53(Fe), optimizing interfacial charge transfer and light absorption, and ensuring effective spatial segregation of photogenerated carriers, thereby maintaining robust redox potentials. The modified CdS/Fe-MOF exhibited exceptional catalytic performance, achieving 92% degradation of 40 mg·L–1 tetracycline within 15 min, surpassing pure CdS (43%) and MIL-53(Fe) (30%) by factors of 2.3 and 3.3, respectively. Mechanistic studies identified on-site H2O2 generation through two-step oxygen reduction (236 μmol·L–1) and its subsequent activation by Fe3+/Fe2+ cycling to produce ·OH as key pathways, with h+, ·O2–, 1O2, and ·OH collectively driving pollutant degradation. The prepared photocatalysts demonstrated remarkable stability (>90% efficiency after five cycles) and structural integrity, attributed to the robust heterojunction interface. This study provides deep insight into designing Z-scheme photo-Fenton catalysts and advancing sustainable wastewater treatment.