Bismuth oxyhalide modified bimetallic Ce/Zr-MOF to construct Z-scheme heterojunction for enhanced visible light photocatalytic degradation of typical antibiotics

The rapid recombination of photogenerated charge carriers is a major challenge for photocatalysts. In this study, a novel Z-scheme heterojunction photocatalyst was synthesized via a hydrothermal method by coupling bimetallic Ce/Zr-NH 2 -UiO-66 (CNU) with solid solution of BiOCl 0.7 I 0.3 (Bi-0.3) for ciprofloxacin (CIP) degradation. The catalyst combines the excellent charge separation ability of Ce/Zr bimetallic metal organic framework (MOF) with the broad light absorption of solid solution of bismuth oxyhalide, achieving outstanding photocatalytic performance under visible light. The characterization results demonstrate that the formation of the Z-scheme heterojunction significantly enhances the material's visible light absorption and promotes efficient electron-hole separation through the built-in electric field, thereby effectively suppressing the recombination of photogenerated charge carriers. Photoelectrochemical and radical trapping experiments further demonstrated excellent interfacial charge transfer and reactivity. The catalyst achieved a CIP removal efficiency of 90.06 ± 2.78 % within 90 min and exhibited good stability in various water matrices. The response surface methodology analyzed the interactions between key reaction parameters, while density functional theory (DFT) confirmed that the electron transfer mechanism follows a Z-scheme heterojunction. It also predicted the degradation pathway of CIP and identified the primary attack sites, along with evaluating the environmental toxicity of the intermediate products. This study provided new insights into the design of bimetallic MOF-based Z-scheme heterojunction and expands the application potential of photocatalysts for environmental remediation.