Balanced generation of holes and superoxide radicals on Bi25CoO40 sillenite photocatalysts for rapid synergetic degradation of quinolone antibiotics

Abstract

Herein, Bi₂₅CoO₄₀ sillenite nanosheets with a thickness of approximately 1.4 nm were successfully prepared. These nanosheets exhibit broad solar spectrum absorption beyond 900 nm and excellent photodegradation of ciprofloxacin. The degradation rate of Bi₂₅CoO₄₀ nanosheets reached 0.327 min⁻¹, which is 4.2 times higher than that of Bi₂₅CoO₄₀ nanoparticles and 8.1 times higher than that of the well-known P25-TiO₂ catalyst. The enhancement is attributed to the significant exposure of the (400) plane in the Bi₂₅CoO₄₀ sillenite nanosheets, leading to the generation of a strong internal electric field that promotes charge spatial separation. This enables a more balanced generation of holes and superoxide radicals for both the cleavage of the quinolone ring and the defluorination, thereby enhancing photocatalytic activity. This work provides valuable insights into the degradation of pollutants and contributes to the design of efficient photocatalyst materials.