Synergistic surface plasmon resonance and S-scheme charge migration in oxygen vacancy rich TiO2/Bi19Br3S27/Bi nanostructures enabling outstanding photocatalytic degradation of pollutants

Background Dye and pharmaceutical pollution in water bodies poses a serious worldwide challenge, endangering both aquatic ecosystems and human health because of their durability, harmful effects, and potential to cause cancer, making urgent intervention. Methods In this study, plasmonic TiO2-X/Bi19Br3S27/Bi photocatalysts were successfully formulated through a two-step hydrothermal method using sodium borohydride as a reducing agent. The synthesized photocatalyst exhibited greatly improved photocatalytic performance in the degradation of various pollutants, including azithromycin (AZM), tetracycline hydrochloride (TCH), and cephalexin (CPN), and three dyes, including methyl orange (MO), methylene blue (MB), and rhodamine B (RhB). Key improvements are superior redox efficiency resulting from the highly negative conduction potential of Bi19Br3S27, improved visible-light response induced by bismuth nanoparticles and defects formed in TiO2 (abbreviated as TiO2-x), efficient separation rate and photoinduced charge carrier transport, creation of active sites and species, development of S-scheme mechanism between the photocatalyst counterparts, and quantum size of the synthesized photocatalysts. Significant findings The impact of Bi19Br3S27 nanoparticles (5, 10, and 20 wt%) on the performance of TiO2-X was investigated to determine the optimal photocatalyst composition. The highest photocatalytic degradation of TCH was achieved by the TiO2-X/Bi19Br3S27 (10 %) nanocomposite (98 % in 180 min). The optimized TiO2-X/Bi19Br3S27/Bi-2 nanocomposite achieved a TCH degradation rate of 99.7 % within 60 min with a reaction rate constant of 1002 × 10‒4 min‒1, which was 4.81 times of TiO2-X/Bi19Br3S27 (10 %), 16.6 folds of Bi19Br3S27, 14.6 times of TiO2, and 4.41 as high as TiO2-x under the identical conditions. The TiO2-X/Bi19Br3S27/Bi-2 nanocomposite exhibited stability across four reuse cycles, while its compatibility with biological systems was shown by successful lentil seed growth in the treated solution. This work introduces an innovative nanocomposite designed for the degradation of dyes and the elimination of antibiotics with usability in plant irrigation applications. © © 2025. Published by Elsevier B.V.