Enhanced degradation of micropollutants by visible light photocatalysts with strong oxygen activation ability

Visible light photocatalysis is widely considered a sustainable approach to break down micropollutants without chemical addition. To promote the output of photogenerated carriers under visible light, a Z-scheme plasmonic photocatalyst Bi-CeO₂/Ag⁰/BiO₂ was designed and fabricated to activate dissolved oxygen in water for micropollutant degradation. The doped Bi not only improved the separation of electron-hole, but also narrowed the band gap of CeO₂ to enhance its absorption of visible light. Notably, metallic silver (Ag⁰) works as an electronic transmission vehicle from Bi-CeO₂ to BiO₂ in a Z-scheme mechanism. Likewise, the surface plasmon resonance effect of Ag⁰ also enhanced the absorption of visible light. Furthermore, the Bi doping induced abundant surface oxygen vacancies on CeO₂ for enhanced capability and selectivity towards O₂ adsorption and activation, which favored the generation of O₂^•- by photogenerated electrons to degrade sulfamethoxazole, enrofloxacin, and bisphenol A. Theoretical calculation results also confirmed the O₂^•--driven degradation pathway for sulfamethoxazole. Therefore, the Z-scheme Bi-CeO₂/Ag⁰/BiO₂ not only extends the photocatalytic reactivity of CeO₂-based catalysts to the visible light range, but also provides a chemical-free method to effectively degrade micropollutants.