Bimetallic-organic frameworks derived Bi-doped CeO2 nanorods with oxygen vacancies for boosted photo-Fenton activity

Metal ions doping has attracted noteworthy attention for tuning the electronic structure of semiconductors. However, high doping content usually leads to the formation of heterophase or impurity. Herein, ultra-high Bi-doped CeO₂ nanorods (doping amount up to 20 mol%) without dopant segregation were fabricated by pyrolyzing Bi/Ce bimetallic-organic frameworks (Bi/Ce-BMOFs), and adaptive oxygen vacancies (OVs) were introduced. The Bi-doped CeO₂ not only retains the unique porous structure of Bi/Ce-BMOFs, thus possessing a large specific surface area, but also significantly enhances the visible-light response and promotes the redox cycling of Ce³⁺ /Ce⁴⁺ ion pairs, thereby accelerating the efficient activation of H₂O₂. Moreover, the adaptive OVs serve as electron-trapping sites, further facilitating the separation of charge carriers. Consequently, the Bi-doped CeO₂ exhibits an excellent photo-Fenton degradation efficiency of tetracycline (TC) over a broad pH range (pH = 2–9). Mechanistic studies revealed that ·O₂^– and ⋅OH are the dominant reactive species. Additionally, the possible degradation pathways of TC were explored using joint characterizations. The ecotoxicity of intermediate products formed during the degradation process was also assessed. This work demonstrates the great potential of the Bi-CeO₂ heterojunction in antibiotic degradation and risk control, providing a feasible strategy for designing efficient and stable catalyst with heteroatom doping derived from BMOFs.