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/Ag-0/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 (Ag-0) works as an electronic transmission vehicle from Bi-CeO2 to BiO2 in a Z-scheme mechanism. Likewise, the surface plasmon resonance effect of Ag-0 also enhanced the absorption of visible light. Furthermore, the Bi doping induced abundant surface oxygen vacancies on CeO2 for enhanced capability and selectivity towards O-2 adsorption and activation, which favored the generation of O-2(center dot-) by photogenerated electrons to degrade sulfamethoxazole, enrofloxacin, and bisphenol A. Theoretical calculation results also confirmed the O-2(center dot-)-driven degradation pathway for sulfamethoxazole. Therefore, the Z-scheme Bi-CeO2/Ag-0/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.