Oxygen Vacancy-Enriched BiVO4/TiO2 S-Scheme Heterojunction for Efficient Visible-Light Photocatalytic Degradation of Tetracycline Hydrochloride

Tetracycline hydrochloride (TCH) contamination poses serious environmental risks due to its persistence and bioaccumulation. Here we present an oxygen-vacancy-enriched BiVO4/TiO2 S-scheme heterojunction (5% BVO/TO) synthesized via a one-step solvothermal method. Under visible light (λ > 420 nm), this composite achieves 78.8% TCH degradation in 80 min, outperforming TiO2 (69.5%) and BiVO4 (34.1%). Its rate constant (0.0198 min−1) is 1.4 and 4.0 times higher than TiO2 and BiVO4, respectively, while retaining over 70% activity after four cycles. XPS and EPR confirm that oxygen vacancies serve as electron traps to suppress recombination, and UPS combined with DFT calculations validates directional electron transfer from BiVO4 to TiO2. Radical scavenging tests and in situ EPR reveal h+ > •OH > •O2− as the dominant reactive species. This study offers a robust design strategy for OV-enhanced S-scheme photocatalysts toward efficient, sustainable degradation of antibiotic pollutants.