In Silico-Directed Design and Experimental Validation\nof an IL/UiO-66 Nanocomposite with Exceptional CO<sub>2</sub> Selectivity\nacross a Wide Pressure Range

Ionic liquid (IL)/metal–organic\nframework (MOF) (IL/MOF)\nnanocomposites have been shown to offer a broad potential in adsorption-based\nCO<sub>2</sub> separation, especially at very low pressures. Selection\nof the most suitable ILs is crucial for synthesizing IL/MOF nanocomposites\ncapable of achieving exceptionally high CO<sub>2</sub> selectivities\nunder more applicable conditions, such as at atmospheric pressure.\nHowever, the existence of a very wide range of IL-MOF pairs makes\nthe design of such materials time-consuming when relying solely on\nexperimental approaches. In this work, we employed a multitiered computational\napproach involving conductor-like screening model for realistic solvents,\ngrand canonical Monte Carlo simulations, and density functional theory\ncalculations. The goal was to screen 35,476 diverse ILs from various\nfamilies to identify the IL that could boost the CO<sub>2</sub> selectivity.\nResults of the computational screening highlighted 1-<i>n</i>-butyl-3-methylimidazolium tricyanomethanide ([BMIM][C(CN)<sub>3</sub>]) as the promising IL candidate offering significant potential for\nseparation of CO<sub>2</sub> from N<sub>2</sub> and CH<sub>4</sub>. We then experimentally incorporated this IL into a robust MOF,\nUiO-66, and characterized the resulting structure in deep detail.\nTesting of [BMIM][C(CN)<sub>3</sub>]/UiO-66 for adsorption of CO<sub>2</sub>, N<sub>2</sub>, and CH<sub>4</sub> demonstrated that the\nnanocomposite provides exceptional CO<sub>2</sub> separation performance,\noffering an appreciable amount of CO<sub>2</sub> uptake, while almost\ncompletely rejecting N<sub>2</sub> and CH<sub>4</sub> up to 1 and\n0.3 bar, respectively, at 25 °C. Our results illustrated the\nimportance of accurate selection of the IL for the design of IL/MOF\nnanocomposites with high performance for target gas separations.