Synergistic enhancement of Z-scheme (SiO2/TiO2)/Bi2WO6 heterojunction by oxygen vacancies and interfacial electric field for efficient degradation of antibiotics

Synthesis of efficient photocatalysts is essential for the removal of antibiotic-based contaminants from wastewater. In this work, novel Z-scheme (SiO2/TiO2)/Bi2WO6 (SiTiBi) heterojunction photocatalysts are synthesized by atomic layer deposition and hydrothermal methods, and the photocatalytic performance is improved by constructing oxygen vacancies and internal electric field (IEF). 15-SiTiBi (15 wt% SiO2/TiO2) exhibits excellent photocatalytic activity, with 89 % LVF degradation in 30 min and a degradation kinetic constant of 0.072 min- 1 . In addition, based on free radical trapping, electron spin resonance, photoelectrochemical tests, and DFT calculations, show that oxygen vacancies enhance the light absorption, and IEF strengthens the separation and migration of photogenerated carriers. Finally, the degradation intermediates and degradation pathways of LVF are predicted using LC-MS and first-principles. This work provides an effective method for constructing interfacial structures that facilitate the separation of photogenerated carriers and promote antibiotic degradation.