Membrane-based gas separation is currently attracting tremendous attention as this unit operation has been considered as one of the available strategies that can contribute toward carbon neutrality. Nevertheless, polymeric membranes suffer from material-related limitation, namely the permeability/selectivity trade-off as exemplified through the Robeson plot due to the intrinsic properties of polymers. Recently, a new rising star in 2D nanomaterial, MXenes, shows a new route to produce high-performance gas separation membranes. This study investigates the potential utility of 2D MXenes as nanofillers to enhance the gas separation performance of polydimethylsiloxane (PDMS) membrane, which generally possesses high intrinsic permeability but low selectivity. Thus, we fabricated mixed-matrix membranes by incorporating multilayer MXene (ML-MXene) and single-layer MXene (D-MXene) under different loading (1�5 wt) into PDMS matrices. The addition of MXene improved the separation capacity of the rubbery dense layers. Based on the optimization study performed in this work, D-MXene-loaded mixed-matrix membrane at 1 wt loading demonstrated an increment in both CO2 permeability and CO2/N2 selectivity by 64.1 and 21.3, respectively, with respect to pure PDMS membrane. © 2023 Elsevier Ltd