Effect of spin-coated and blade-casted MXene-polydimethylsiloxane asymmetric thin film composite membranes towards effective H2 and CO2 separation performance involving quaternary gas mixture

Mixed-matrix membranes (MMMs) have been widely studied for gas separation. However, MMMs have been mainly developed in a dense symmetric manner. Hence, such membranes suffer from high gas transport resistance, limiting their practical applicability. Thus, asymmetric MMMs were prepared by embedding MXene into a polymer matrix using the blade casting and spin coating method. The differences in the gas permeation were observed despite utilizing the identical dope solution and membrane thickness. Spin-coated membranes showed uniformly dispersed but randomly aligned MXene, forming loosely packed layers that facilitate gas transport. In contrast, blade-cast membranes exhibited dense and highly aligned MXene that hinders the permeation of gas molecules. Consequently, spin-coated membranes achieved higher H 2 and CO 2 (1.9 and 1.8 times) permeance and selectivity (H 2 /N 2 (9.7) and CO 2 /N 2 (17.5)) as compared to blade-cast membranes. These results underscore the critical role of utilizing appropriate coating methods to optimize the gas separation performance. • MXene alignment in the membrane is influenced by the fabrication method. • Spin-coating method yields dispersed and loosely packed MXene layers. • Blade-casted membranes lead to dense and aligned MXene. • Spin-coated membranes show higher gas permeability and mixed-gas selectivity. • The highest filler enhancement index was observed in H 2 /N 2 separation.