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.