Boosting visible-light photocatalysis of tetracycline through Eu3+ doping in hydrothermally synthesized Bi2WO6 composites

The rapid charge recombination in Bi 2 WO 6 severely limits its photocatalytic efficiency for antibiotic wastewater treatment. To address this, Eu 3+ -doped Bi 2 WO 6 was synthesized via controlled hydrothermal method, exhibiting 2.5-fold enhanced tetracycline (TC) degradation kinetics (0.05889 min −1 ) and 23 % higher efficiency than pristine Bi 2 WO 6 under visible light. Comprehensive characterization reveals three synergistic mechanisms: first, Eu 3+ incorporation induces lattice distortion and charge imbalance, generating oxygen vacancies that act as electron traps to suppress recombination; second, UV-Vis DRS shows bandgap narrowing from 2.8 to 2.3 eV enabling broader light absorption; third, electrochemical impedance spectroscopy demonstrates 3.1-fold improved charge separation efficiency. ESR and radical trapping experiments identify h + and ·O 2– as the dominant active species, with the former contributing approximately 68 % of the degradation activity according to quantitative analysis. The catalyst retains 88.57 % activity after four cycles, showing superior stability. This work provides atomic-level insights into rare-earth doping effects on charge carrier dynamics, offering a viable strategy for designing visible-light photocatalysts.