Synergistic integration of oxygen vacancy enrichment and Z-scheme heterojunction in novel BiO/TiO photocatalyst for enhanced tetracycline degradation in wastewater.

The novel Z-scheme heterojunction BiO/TiO photocatalytic system with oxygen-rich vacancies was constructed in this paper, which realized the efficient degradation of tetracycline. The tetracycline was 92.2 % removed by BiO/TiO after 60 min of visible-light driving, which is not only attributed to the high density of oxygen vacancies (0.3676 a.u.), but also depends on the synergistic integration of oxygen vacancies with Z-scheme heterojunctions. It is shown that the electron transfer energy from the oxygen vacancy-induced intermediate energy level in BiO/TiO to the BiO valence band is significantly lower than that from the TiO conduction band, which contributes to the establishment of the Z-scheme charge transfer mechanism. Meanwhile, the intermediate energy level in the system can trap and stabilize the photogenerated electrons, thus reducing the electron-hole complexation rate. Combined with chromatography-mass spectrometry, density functional theory and toxicity assessment studies, the series of tetracycline degradation intermediates and their corresponding transformation pathways in the BiO/TiO photocatalytic system were revealed, confirming that this technology can reduce the risk of the global ecological spread of tetracycline antibiotics. This study provides a new design paradigm for oxygen vacancy engineering to modulate Z-scheme heterojunction, which shows application prospects in the field of treatment of antibiotic pollution in wastewater.