Antibiotics photodegradation over recycling Z-scheme Bi₂Ti₂O₇@Bi₂S₃/PU with super-efficiency: DFT calculation, toxicity of oxytetracycline intermediates and photoactivation mechanism

Inspired by the high sustainability, energy saving, cleanliness of photocatalysis (PC) with respect to antibiotics decomposition, we developed a stable, highly efficient Bi₂Ti₂O₇@Bi₂S₃/polyurethane (BTO@Bi₂S₃/PU) photocatalytic system. It exhibited the best degradation performance with the removal of 82.08 % oxytetracycline (OTC) within 180 min under the optimal reaction parameters. Systematic characterization of BTO@Bi₂S₃/PU revealed its wider light-harvest capacity, higher electron–hole (e⁻–h⁺) separation efficiency, lower interface resistance, and better redox potential in heterojunction. Based on electrochemical characterization and density functional theory calculation, the construction of Z-scheme BTO@Bi₂S₃ photocatalyst substantially optimized the band structure. Moreover, the redox cycles of Bi³⁺/Bi⁵⁺ and Ti⁴⁺/Ti³⁺ further enhanced the charge transfer rate during the photoactivation process. For the OTC photodegradation pathways, ·OH, h⁺, ·O₂⁻, and ¹O₂ dominated the pollutant decomposition and the toxicity of intermediates were decreased. Overall, the BTO@Bi₂S₃/PU photocatalytic system may provide a universal and stable technique for advanced photoheterojunction applications and wastewater purification.