Nonstoichiometric Modulation for Defect Engineering in Ce-UiO-66 Beyond Zr-UiO-66

The rational introduction of structural defects into metal-organic frameworks (MOFs) is an effective strategy to enhance catalytic performance. However, precise defect modulation in Ce-UiO-66 remains challenging because Ce(IV) is readily reduced under solvothermal conditions, leading to the formation of thermodynamically stable cerium formate byproducts, unlike the prototype Zr-UiO-66 system. In this study, a series of Ce-UiO-66 samples with tunable defect densities was synthesized via a nonstoichiometric modulation approach, enabling control of defect concentration by adjusting the Ce-to-linker ratio. Catalytic performance was evaluated using the hydrolysis of dimethyl 4-nitrophenyl phosphate (DMNP) as a nerve-agent simulant. The results show that defect-rich Ce-UiO-66 samples exhibit significantly enhanced catalytic activity, with a linear correlation between activity and defect concentration, even as long-range order breaks. This work provides a straightforward and environmentally friendly strategy for defect engineering in Ce-MOFs and highlights their potential for the catalytic detoxification of hazardous compounds.