Molecular simulation study on CO2 separation performance of GO/ionic liquid membrane

•Gas transfer with different IL loading and layer structure were studied.•Gas separation were attributed to the interfacial compactness and free volume.•Effect of SILM deformation on selectivity was weakened by narrow-pore.•Structural heterogeneity affecting gas separation was highlighted. The supported ionic liquid membrane (SILM) has advanced to a promising solution for CO2 capture. It has been extensively studied owing to its high efficiency and complexity. Here, we showed that various heterogeneities, such as ionic liquid (IL) loading and pore size, are likely to affect CO2 transport and separation behavior within the SILMs by molecular dynamics simulation. Our results reported that the intra-membrane further controls the gas selectivity and permeability mainly through its effect on the compactness of the gas-liquid interface and the free volume within the membrane. Additionally, compared with a wide-pore monolayer, the confined space effect of a narrow-pore bilayer is more significant, and the influence of the deformation (flexibility and rigidity) on separation is weakened. This study highlighted the effect of structural heterogeneity on gas separation at a molecular level, which might facilitate the development of 2D-materials. [Display omitted]