Enhanced adsorption and photocatalytic activity for Fe-based MOFs via dual metallic sites regulation

The efficient removal of emerging organic pollutants from water poses a significant challenge in the field of water treatment. In this study, we proposed that introducing dual metallic sites into an iron-based metal-organic framework (MOF) could synergistically enhance both adsorption capacity and photocatalytic activity. To test this hypothesis, we successfully incorporated cerium into MIL-101(Fe) via a simple one-pot hydrothermal method, synthesizing a series of Ce/Fe bimetallic MOFs. Systematic characterization results revealed that Ce doping effectively modulated the material's electronic structure, markedly enhancing visible light absorption by narrowing the bandgap from 2.81 to 2.75 eV and promoting photogenerated charge separation. The 0.1Ce/Fe-1 composite demonstrated superior chloramphenicol (CTC) adsorption, with a saturated capacity of 1551 μmol/g and rapid equilibrium attainment within 60 min. This material attained a 98.2% removal efficiency for 10 mg/L CTC within 1 h under visible light, the corresponding apparent rate constant (0.0107 min −1 ) was 26.75 times that of pristine material. Trapping experiments confirmed that •OH and •O₂⁻ radicals were the predominant active species responsible for the photocatalytic degradation. This material maintained high efficiency and stability across wide pH range, exhibited good resistance to humic acids and common ions, and demonstrated excellent removal capacity (>89.3%) and cycling stability (94.0% efficiency retained after five cycles) in actual water samples. This work demonstrates the efficacy of dual-metal-site regulation as a viable strategy to concurrently enhance both the adsorptive and photocatalytic functionalities of MOF-based materials, offering a novel pathway for developing highly efficient and stable functional materials for water treatment.