Robust and versatile metal–organic frameworks (MOFs) have emerged as a sophisticated scaffold to meet the critical needs of the nuclear community (e.g., fission product capture, radiation detection, and actinide/lanthanide separations). The performance of MOF materials in such applications, however, is inextricably linked to their structural integrity under ionizing radiation, and this key property is relatively underexplored. In this presentation, we identify the contributions of the selected metal node in the radiation stability of the isostructural M-UiO-66 series (where M = Ce, Hf, Th, and Pu). MOF samples were irradiated via gamma and He<sup>2+</sup> ion methodologies to obtain doses up to 3 MGy and 85 MGy, respectively, the latter strikingly higher than that obtained in most other studies. Appreciable self-irradiation constituted the total absorbed doses of the isotopically weapons-grade Pu-UiO-66 samples. Structural degradation was ascertained by powder X-ray diffraction, vibrational spectroscopy, and where possible, N<sub>2</sub> physisorption isotherms. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) probed atomic-level mechanistic insight to reveal the node-linker connection was most susceptible to radiation damage. Density functional theory (DFT) truncated cluster models were optimized to evaluate the binding affinity of linkers to each metal node. While the isostructures disclosed the same breakdown signatures, distinct radiation sensitivity as a function of metal selection was evident. We hope these endeavors will contribute to the rational design of radiation-resistant materials for targeted applications.

Role of metal selection in the radiation stability of isostructural M-UiO-66 metal–organic frameworks

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