Interface-enhanced CO 2 capture via the synthetic effects of a nanomaterial-supported ionic liquid thin film.

Ionic liquids (ILs) are effective CO 2 capture media and recent experimental evidence has demonstrated that the addition of two-dimensional (2D) nanomaterials into ILs can effectively improve their CO 2 capturing capability. However, an in-depth mechanism on how 2D nanomaterials enhance CO 2 absorption is poorly documented. In this study, the adsorption of CO 2 by a representative IL, namely 1-ethyl-3-methyl-imidazole-tetrafluoroborate ([EMIM][BF 4 ]), coated on graphene (GRA, the prototype 2D nanomaterial) and nitrogenized graphene (C 3 N) was investigated by molecular dynamics simulations. The influence of the IL film thickness on the amount of CO 2 adsorption was systematically analyzed. Our data clearly indicate that at the IL-gas interface the CO 2 accumulation is significantly enhanced. In contrast, at the IL-GRA and IL-C 3 N interfaces, only slight enhancement was observed for CO 2 accumulation. Quantitative calculations of the adsorption-free energy for CO 2 inside the IL film further support the simulation results. Our present results also reveal that the sub-nanometer IL film possesses a considerably high CO 2 capture efficiency because of the formation of the reduced bulk IL region. Moreover, the nanomaterial substrate surfaces can effectively accelerate the diffusion of CO 2 , which is beneficial for the CO 2 mass transfer. In general, our theoretical study provides a deep microscopic understanding of the CO 2 capture by nanomaterials and IL composites. These results could benefit the design and fabrication of a high-performance CO 2 capture and storage medium through the synthetic effects of ILs and nanomaterials.