Europium‐Modified Urea‐Assisted TiO ₂ Nanoparticles as Multifunctional Materials for Natural Sunlight‐Driven Photocatalysis, Antimicrobial Defense, and Anticancer Activity

ABSTRACT Europium‐doped urea‐assisted TiO 2 (Eu:U‐TiO 2 ) nanoparticles were synthesized via a hydrothermal method with Eu doping levels of 1, 3, and 5 wt%, together with undoped U‐TiO 2 as a reference. Structural, morphological, surface, and optical properties were systematically characterized. Photocatalytic activity was assessed under natural sunlight via the degradation of methylene blue (MB), acid black 1 (AB 1), and reactive red 120 (RR 120). The 3 wt% Eu:U‐TiO 2 catalyst exhibited superior performance, achieving near‐complete degradation of MB (10 ppm) and degradation efficiencies of 81.06% for AB 1 (20 ppm) and 63.28% for RR 120 (50 ppm) within 90 min under optimized conditions (pH 9, 20 mg catalyst per 100 mL). Kinetic analysis followed pseudo ‐first‐order behavior, with the highest rate constant observed for the 3 wt% Eu‐doped sample. In parallel, antibacterial activity against both Gram‐positive and Gram‐negative bacteria demonstrated a marked enhancement for Eu‐doped samples compared to undoped U‐TiO 2 . Radical scavenging experiments and GC–MS analysis identified O 2 • − and • OH radicals as the dominant reactive species responsible for dye mineralization. Overall, the optimized 3 wt% Eu:U‐TiO 2 functions as a multifunctional material, integrating efficient sunlight‐driven photocatalysis with significant antibacterial activity, and shows strong potential for combined environmental remediation and biomedical applications.