Designed and constructed the lamellar MXene/PVA composite membrane for H2/CO2 separation

Two-dimensional MXene materials exhibit significant promise in hydrogen separation membranes, especially for the effective separation of H 2 /CO 2 mixtures, thanks to their structured interlayer channels and profusion of surface functional groups. However, in humid or watery conditions, MXene membranes are susceptible to interlayer swelling, which significantly impairs their ability to separate materials. In order to improve the hydrothermal stability of MXene membranes for effective H 2 /CO 2 separation, we used polyvinyl alcohol (PVA) to intercalate between the MXene nanosheets and cross-link them via heat treatment. The method of heat cross-linking makes it easier for the functional groups of PVA and MXene nanosheets to connect, giving the membrane superior molecular sieving capabilities. Additionally, PVA improves MXene's interlayer spacing, resulting in quicker gas transport paths. MXene's size-selective characteristics and surface adsorption capability efficiently inhibit CO 2 diffusion while facilitating H 2 permeation. The resultant 20 % PMM composite membrane demonstrates a H 2 permeance of 1453 GPU and a H 2 /CO 2 selectivity of 45, sustaining steady separation performance during 72 h of operation, including 20 h in a humid environment. • The integration of polyvinyl alcohol (PVA) between MXene nanosheet layers and subsequent thermal crosslinking improves the hydrothermal stability of the MXene membrane. • The incorporation of PVA enhances the interlayer spacing of MXene, facilitating gas permeation. • The resultant 20 % PMM composite membrane exhibited a H 2 permeance of 1453 GPU and a H 2 /CO 2 selectivity of 45, surpassing the polymeric membranes upper bound.