Novel high-valent copper species-involved photo-Fenton-like process boosted by nitrogen/oxygen dual defects modulation

High-valent metal species generated during peroxymonosulfate (PMS) activation have demonstrated significant potential in wastewater treatment. However, the rapid generation of high-valent metal species, especially high-valent copper (Cu(III)), has been challenging. Moreover, the mechanisms behind Cu(III) generation and its role in the PMS-based Fenton-like process have not been fully understood. Herein, a novel N, O dual defects co-modified 0D/2D hybrid of CuO nanodots (NDs)/g-C3N4 nanosheets was constructed as an integrated photocatalytic platform to efficiently activate PMS, which exhibited excellent catalytic activity and stability towards tetracycline degradation through consecutive generation of surface Cu(III) as the key active species. The N, O dual-defects and strong interfacial coupling of NDs/g-C3N4 markedly increased charge separation and induced electron-rich Cu sites. This led to a continuous and rapid Cu(II)/Cu(I) conversion, further triggering persistent Cu(III) generation through Cu(I)-oxidation with a two-electron transfer. The work provides new insights into exploring the properties of Cu(III) species during PMS activation and offers encouraging guidance for their application in pollutant removal.