PIM-1-based membranes mediated with CO2-philic MXene nanosheets for superior CO2/N2 separation

Membrane gas separation technologies have emerged as highly prospective avenues for the selective separation of CO 2 . In this research, a novel array of mixed-matrix membranes (MMMs) was engineered, integrating two-dimensional nanosheets of MXene, specifically Ti 3 C 2 T x , into polymers of intrinsic microporosity (PIMs) to selectively separate CO 2 from N 2 . The inclusion of Ti 3 C 2 T x nanosheets, rich in polar functional groups, significantly increases the affinity between CO 2 molecules and the fabricated MMMs. Additionally, the precise modulation of the molecular diffusion channels for CO 2 and N 2 is achievable due to the interlayer spacing between MXene layers (∼0.35 nm) within the PIM-1 matrix. This innovation is predicated on the synergistic effect of solution-diffusion and molecular sieving mechanisms that underpin the gas separation process, leading to a marked improvement in both selectivity for CO 2 over N 2 and the permeability of CO 2 . Among the series, the MMMs with a 0.5 wt% MXene display exceptional separation efficiency, achieving a CO 2 permeability of 12475.3 barrer and a CO 2 /N 2 selectivity of 32.7. Notably, all the PIM-1/MXene membranes prepared with different compositions in this study exceed the Robeson upper bound defined in 2019, indicating their substantial promise for CO 2 separation and capture in industrial applications.