Facile synthesis of oxygen vacancy-rich BiMnx composites for enhancing antibiotic removal driven by LED visible light

Abstract

NaBiO₃ is a low-cost photocatalyst with good performance for organic removal. Oxygen vacancies (OVs) play crucial roles in mediating oxygen activation and electron-hole separation during visible light-driven photocatalysis. In this study, Mn ions were doped into the commercial NaBiO₃ by a facile in-situ technique to construct OVs for enhancing sulfamethazine (SMT) removal. By doping 0.001–0.01 mmol of Mn^2 + ions, abundant OVs were formed on the initial NaBiO₃ surface, endowing the as-prepared BiMn_x composites (e.g. BiMn_0.001) with a fast kinetic (first-order rate constant k 0.68 h⁻¹) and a high efficiency (>99 % within 6 h) for SMT degradation. Excellent removal of SMT could be attained across a broad pH range (i.e. pH₀ 5–9) using BiMn_0.001 as the photocatalyst, which could harvest full-spectrum LED white light and showed anti-interference to common water co-existent constituents. Increasing solution temperature was also beneficial for SMT removal. Reactive species including ¹O₂, holes and electrons played dominant roles for SMT removal. Based on HPLC-MS, the degradation intermediates were identified, and a degradation pathway for SMT was formulated in the BiMn_x/LED system. The results may shed some light for constructing OVs on catalyst surfaces and preparing LED visible light-responsive photocatalysts for antibiotic removal.