Electronic structure modulation of p-n type CeO2/Eu-CN heterojunction system: efficient promotion of photocatalytic degradation of tetracycline

Antibiotic pollution seriously damages the ecological balance of the water environment. Efficient degradation of excessive antibiotics in water is worth further exploration. Photocatalytic antibiotic degradation not only makes full use of solar energy, but also exhibits high degradation efficiency and no by-product generation. In this paper, a novel yCeO₂/5Eu-CN photocatalyst with a p-n heterojunction was successfully synthesized by solid-phase methodology, which can effectively photodegrade the antibiotic tetracycline under visible light. Firstly, rare earth Eu ions were doped into the layered g-C₃N₄ prepared by melamine calcination, and then combined with CeO₂ to obtain the effective composite photocatalyst 0.3CeO₂/5Eu-CN. Catalytic exploration indicates that it can effectively photodegrade tetracycline antibiotics with a degradation of 94.0 %, and is recycled three times without loss of photoactivity. Control experiments show 5Eu-CN photocatalyst possesses abundant hole states with a certain width and DOS distribution of VBM through the hybridization of N 2p and Eu 3d, which not only provides more active sites but also exhibits a unique very narrow energy band structure, showing p-type semiconductor characteristics. In addition, 5Eu-CN photocatalyst composites with the n-type semiconductor CeO₂ to form the p-n heterojunction 0.3CeO₂/5Eu-CN. The composite structure efficiently promoted the separation and migration of photogenerated carriers by utilizing the different energy bands of the two semiconductors, significantly suppressing electron-hole pair complexation and enhancing the photocatalytic efficiency. Theoretical calculation also reveals the charge transfer and interaction at the p-n heterojunction interface. This work has achieved innovation in the entire chain of “material design structure – optimization − mechanism elucidation”, providing clearer ideas and theoretical basis for the design of high-performance p-n heterojunction photocatalysts.