Sequestration of Radionuclides in Metal-Organic Frameworks from First Principles Calculations
Shubham Pandey1 , Zhilin Jia1 , Brian Demaske1 , Natalia Shustova2 , Ekaterina Dolgopolova, Wahyu Setyawan3 , Charles H. Henager3 , Simon R. Phillpot1
1Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611, United States
2Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
3Nuclear Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, United States
Metal-organic frameworks (MOFs) could lead to development of novel class of hybrid materials emerging as potential wasteforms to sequester nuclear waste. Density Functional Theory (DFT) calculations were used to determine the favorability of substitution of relevant radionuclides in various parent MOF clusters. The radionuclides of interest are U, Th, Am, Cm and Tc. Results from various levels of treatment of the exchange-correlation functional are compared to establish the robustness of the results. Various other DFT methods such as effect of electron localization (+U corrections), effect of spin-orbit coupling (SOC), hydration of ions and tuning of hybrid functionals are also investigated. We find that Tc incorporation is energetically well-favored in all of the MOFs considered. The electronic structures of both the actinide-based MOFs and radionuclide substituted MOFs are analyzed and correlated with experimental data. We also study the effect of the electronic properties tunability as a function of transition metal incorporation.
This work was supported by the Center for Hierarchical Waste Form Materials (CHWM), an Energy Frontier Research Center (EFRC) funded by the United States Department of Energy Office of Basic Energy Sciences through Award DESC0016574.