Defect-Regulated Charge Dynamics and Ros Pathways in Lafetio₃ Photocatalysts for Enhanced Antibiotic Degradation Under Uva Irradiation Publisher

Summary: Can crystal defects help remove drug residues from water? Modified LaFeO3 photocatalysts cut organic carbon 44.3%, and lowered toxicity. #Photocatalysis #WaterTreatment

Majidi S ; Ebrahimpour K ; Pourzamani H R
Source: Journal of Photochemistry and Photobiology A: Chemistry Published:2027

Abstract

Defect engineering can modify photogenerated charge-carrier behavior in perovskite photocatalysts without necessarily changing their optical band gap. In this study, La vacancies at the A-site were combined with Ti incorporation at the B-site to examine their effects on charge separation and reactive oxygen species (ROS) pathways in LaFeO₃ under UVA irradiation. A series of La₁₋ᵧFe₁₋xTixO₃ (x = 0.1, y = 0–0.15) photocatalysts were synthesized by a sol–gel method and evaluated for metronidazole (MTZ) degradation. The defect-engineered perovskite showed a similar optical band gap (~3.28 eV) to the reference material but higher photocatalytic activity, achieving nearly complete MTZ degradation within 70 min with an apparent rate constant of 0.2241 min−1. Photoluminescence, electrochemical impedance spectroscopy, and transient photocurrent measurements indicated reduced charge recombination and improved charge transfer after introducing La vacancies and Ti. Radical scavenging tests and electron spin resonance measurements showed that •OH was the main reactive species, while O₂•− also contributed to MTZ degradation. The higher contribution of •OH may be associated with electronic-structure changes caused by La vacancies, which may promote Fe3+/Fe2+ redox cycling and Fenton-like •OH generation. LC–MS analysis identified intermediates associated with hydroxylation, denitrification, and ring-cleavage reactions. The treatment achieved 44.3% TOC removal and reduced cytotoxicity based on the HeLa cell assay. The catalyst maintained its structure during repeated cycles, with low Fe/Ti leaching. Overall, the results indicate that combining La vacancies with Ti incorporation affects charge separation and ROS generation in LaFeO₃, supporting its application in photocatalytic treatment of pharmaceutical contaminants. © 2026 Elsevier B.V.