Interfacial V ⁵⁺ /V ⁴⁺ Redox Kinetics Enabling Fe-free Photo-Fenton Catalysis in α-V ₂ O ₅ -ACNT Nanohybrids for Efficient Removal of Mixed CBZ and DFN

Efficient removal of structurally diverse and persistent pharmaceutical contaminants from wastewater, particularly in mixed-pollutant systems, remains a critical challenge in advanced water treatment technologies. Conventional Fe-based photofenton systems suffer from iron (Fe) sludge generation and secondary metal contamination, limiting their practical and sustainable application. Herein, we report Fe-free photofenton catalysis enabled by interfacial V⁵⁺/V⁴⁺ redox kinetics in α- V₂O₅-decorated activated carbon nanotube (α-V₂O₅-ACNT) nanohybrids for simultaneous removal of two emerging pharmaceutical pollutants, diclofenac (DFN) and carbamazepine (CBZ), from their mixed system. Electronic coupling at the V₂O₅/ACNT interface promotes rapid charge separation, abundant oxygen vacancies, and dynamic V⁵⁺/V⁴⁺ redox cycling, which efficiently activates H₂O₂ to generate highly reactive •OH radicals without the need for Fe species. Under optimized conditions, the catalyst achieved ∼96% removal efficiency for DFN and ∼95% against CBZ within 60 min. Transient photocurrent, EPR/ESR, and radical trapping analyses confirm improved charge transport and intensified •OH generation. Density functional theory calculations further reveal favorable adsorption geometries, charge redistribution, and reactive site localization of both pollutants on defect-rich surfaces, rationalizing the observed removal pathways. This study establishes mechanistic synergy between V₂O₅ and ACNTs as an effective strategy for designing sustainable, Fe-free photofenton systems.