Plasmonic bismuth and CuBi₂O₄–Bi₂O₂CO₃ deposition on sulfur-doped g-C₃N₄ for efficiently removing antibiotics upon visible light

Lately, there has been significant focus on pharmaceutical contaminants due to their destructive effects on the environment and potential toxicity to animals, humans, and aquatic ecosystems. An effective strategy to address these challenges is the application of heterogeneous photocatalysis utilizing semiconducting materials, which plays a crucial role in mitigating environmental hazards. In this research, bismuth nanoparticles and CuBi₂O₄–Bi₂O₂CO₃ (denoted as CBO–BOC) were effectively deposited on S-doped g-C₃N₄ (denoted as SCN) through a simple approach. These photocatalysts were employed to purify water contaminated with four different antibiotics (tetracycline hydrochloride (TCH), cephalexin (CPN), azithromycin (AZM), and metronidazole (MET)) upon visible light. The TCH degradation rate over the optimized Bi/CBO–BOC/SCN nanocomposite reached 99.7 % within 75 min, and the degradation constant was 754 × 10⁻⁴ min⁻¹, which was 8.98, 9.08, and 2.52 folds higher than SCN, CBO–BOC, and CBO–BOC/SCN (10 %) photocatalysts, respectively. The enhanced performance was devoted to the presence of metallic bismuth with surface plasmon resonance properties, sulfur doping, and the development of dual Z-type heterojunctions in the developed nanocomposite. This combination promoted the movement of photogenerated electrons while suppressing the recombination of electron/hole pairs, promoted the number of active sites, as well as visible-light harvesting properties. The results provide a simple method for preparing heterogeneous plasmonic photocatalysts for the degradation of common antibiotics, and we expect that they could be applied on a large scale for the treatment of industrial and domestic wastewaters.