Properties and mechanism of uranium adsorption on single-sided fluorinated graphene: A first-principles study

Functionalized two-dimensional materials have been widely explored as possible candidates to adsorb radioactive nuclide due to their large specific surface and tunable properties. In this work, single-sided fluorinated graphene (ssFG) with different fluorinated rates have been predicted to be an effective adsorbent for uranium atoms using density functional theory (DFT) simulations. The linear response method was used to obtain a more accurate Hubbard U value (3.1 eV) of the 5f orbital of the uranium atom. Our calculated results show that uranium atoms were energetically favorable adsorbed on the C2F, C6F, C8F ssFGs, and their adsorption energies are 3.45, 1.20, and 1.12 eV, respectively. The electronic analysis, such as the density of states, charge transfer and differential charge density suggest that the uranium atom has the strongest chemisorption with the substrate C2F. C2F also exhibits excellent performance in terms of the adsorption capacity of uranium atoms. In addition, the critical temperature for the adsorption-desorption transition of uranium atoms was predicted to be 632 K by the adsorption rate equation. The results suggest that ssFG, especially C2F, was a promising material for uranium adsorption, have promising application in nuclear waste disposal, extraction of uranium from seawater, uranium detection, etc.