Efficient Photocatalytic Degradation of Tetracycline Over a Novel Dual Z-Scheme Bi<sub>2</sub>O<sub>3</sub>/ZnTiO<sub>3</sub>–SrTiO<sub>3</sub> Composite Photocatalyst
L.G. Wang, Lu Yang, Shuying Wang, Mengjia Li, Lan Zhang, Huizhong Ma
Abstract
Tetracycline (TC) is a broad-spectrum antibiotic, and its introduction into the environment is known to cause serious water pollution issues and can result in the evolution of drug-resistant genes and superbugs. In this study, a new ZnTiO 3 –SrTiO 3 double perovskite composite photocatalyst, synthesized using a simple molten salt method, was found to exhibit excellent performance in the photocatalytic degradation of TC in an aqueous solution under visible-light photoirradiation at λ = 420 nm. Individually, ZnTiO 3 and SrTiO 3 were identified as being inactive in the same reaction. However, the addition of Bi 2 O 3 to the ZnTiO 3 –SrTiO 3 composite (Bi 2 O 3 /ZnTiO 3 –SrTiO 3 ) formed a dual-Z-scheme heterojunction, achieving 87.1% photocatalytic degradation rate of TC within 60 min. The obtained reaction rate constant ( k = 0.03052 min –1 ) was 9.5 and 1.62 times higher than those achieved using the individual SrTiO 3 ( k = 0.00321 min –1 ) and ZnTiO 3 –SrTiO 3 ( k = 0.01882 min –1 ) species, respectively. Furthermore, a potential degradation pathway and mechanism for TC degradation using the Bi 2 O 3 /ZnTiO 3 –SrTiO 3 composite photocatalyst was proposed. Overall, this approach provides a cost-effective and efficient method for preparing dual Z-scheme heterojunction photocatalysts.