Synergistic interplay between oxygen-vacancy and S-scheme charge transfer dynamics in an LaFeO3/FeOOH heterojunction towards sono-assisted photo-Fenton antibiotic degradation and water splitting

Abstract

The increasing prevalence of pharmaceutical pollutants in water bodies is a significant threat to public health, and there is a need for a sustainable approach to their remediation. Ultrasound-assisted photo-Fenton reactions are considered the most effective approach for active oxidation processes in sustainable and environmentally friendly remediation. This study represents the step scheme (S-scheme) charge transfer dynamics in FeOOH-anchored LaFeO₃ towards the degradation of ofloxacin (OFL) by harnessing ultrasonic waves and simulated solar energy. The heterojunction with intimate interfacial contact and ample oxygen vacancies (O_Vs) was fabricated through a facile two-step sol–gel and in situ coprecipitation method. The optimized catalyst attains superior catalytic activity for sono-photo-Fenton OFL degradation (92.3%) with a “k_app” of 21.95 min⁻¹, which is 2.19 and 2.05 times higher than pristine semiconductors, and an O₂ evolution rate of 1270 μmol h⁻¹ through water splitting. The enhanced catalytic activity is likely ascribed to the facile separation and usage of photogenerated charges through a dynamic S-scheme charge transfer route, the introduction of O_Vs, and continuous charge shuttling between Fe^3+/Fe²⁺. Comprehensive characterizations were undertaken to confirm the structural integrity and physicochemical attributes of the binary heterostructure. EPR, Raman, and XPS studies established the fabrication of O_Vs. Furthermore, the scavenging experiment and EPR analysis confirmed the S-scheme charge transfer pathway. Systematic investigation of various parameters uncovers the catalyst's reaction kinetics, stability, and durability. This dual-function catalyst can be considered a blueprint for the active oxidation process (AOP) for the degradation of toxic environmental pollutants and production of solar fuels.