Decoration of carbon dots on S-scheme TiO_2-x/Bi₂₄O₃₁Br₁₀ heterojunction photocatalyst: Impressive QDs-sized photocatalyst for efficient degradation of common antibiotics and organic pollutants

The effectiveness of photocatalytic materials strongly depends on factors such as stability, light absorption range, charge transfer efficiency, and biocompatibility. Therefore, in the present work, Ti^{3 +} self-doped/oxygen vacancies (Ti³⁺/OVs) TiO₂ was integrated with Bi₂₄O₃₁Br₁₀ and carbon dots and employed for degradation of various organic pollutants (malachite green: MG, methylene blue: MB, and rhodamine B: RhB dyes, tetracycline hydrochloride: TC and amoxicillin: AMX antibiotics). The light-induced charge separation pathway was evaluated through free radical trapping experiments, and it was confirmed that the TiO_2-x, Bi₂₄O₃₁Br₁₀, and carbon dots components collaborated through S-scheme charge transfer pathway. Under the optimal reaction conditions, the TC degradation rate over TiO_2-x/Bi₂₄O₃₁Br₁₀/carbon dots-2 nanocomposite reached 98 % within 30 min, and the reaction rate constant was 1280 × 10^[sbnd]4 min^[sbnd]1, which was 9.70 times of Bi₂₄O₃₁Br₁₀, 5.64 folds of TiO_2-x, and 2.05 folds of TiO_2-x/Bi₂₄O₃₁Br₁₀ (20 %) photocatalysts. Such outstanding performance was attributed to the optimal anchoring of Bi₂₄O₃₁Br₁₀ and C-Dots on the surface of TOVs, the quantum dot size of the resultant photocatalyst, increased surface area, low charge transmission resistance, the effective presence of carbon dots with mediator properties, and most importantly the construction of a S-scheme system which suppressed e^–/h⁺ pair recombination, as confirmed by EIS and PL analyses. The stability and biocompatibility of the TiO_2-x/Bi₂₄O₃₁Br₁₀/carbon dots-2 nanocomposite were confirmed by reusing five times and growing wheat seeds in the treated solution, respectively. This research has presented a novel nanocomposite that can be utilized in dye degradation and antibiotic removal with the aim of plants irrigation.