CO₂-Philic Nanocomposite Polymer Matrix Incorporated with MXene Nanosheets for Ultraefficient CO₂ Capture

The incorporation of two-dimensional (2D) functional nanosheets in polymeric membranes is a promising material strategy to overcome their inherent performance trade-off behavior. Herein, we report a novel nanocomposite membrane design by incorporating MXene, a 2D sheet-like nanoarchitecture known for its advantageous lamellar morphology and surface functionalities, into a cross-linked polyether block amide (Pebax)/poly(ethylene glycol) methyl ether acrylate (PEGMEA) blend matrix, which delivered exceptional CO₂/N₂ and CO₂/H₂ separation performances that are critical to industrial CO₂ capture applications. The finely dispersed Ti₃C₂T nanosheets in the blend polymer matrix led to an expansion of the free volume within the resultant mixed matrix membrane (MMM), giving rise to a substantially enhanced CO₂ permeability of up to 1264.6 barrer, which is 102% higher than that of the pristine polymer. Moreover, these MXene-incorporated MMMs exhibited preferential sorption for CO₂ over light gases, which contributed to an exceptional CO₂/N₂ and CO₂/H₂ selectivity (64.3 and 19.2, respectively) even at a small loading of only 1 wt %, allowing the overall performance to not only surpass the latest upper bounds but also exceed many previously reported high-performance nanosheet-based nanocomposite membranes. Long-term performance tests have also demonstrated the good stability of these membranes. This composite membrane design strategy reveals the remarkable potential of combining a blend copolymer matrix with ultrathin MXene nanosheets to achieve superior gas separation performance for environmentally important gas separations.