Nanoporous materials are highly promising by advancing the prospects of separations, thanks to the rapid permselective gas transport from the pore channels. In this respect, membranes based on zeolites , MOFs, and exfoliated 2D layers (graphene oxide , MXenes , and covalent-organic frameworks(54-57)) have shown promising performances for H2/CO2 separation. However, most studies reporting high performance use zero ∆𝑃 for performance evaluation . Generally, a significant selectivity decline is observed upon pressurization either from the limited stability of transport channels or from the presence of pinhole defects in the selective layer. The latter results in a dominant viscous transport which leads to the loss of selectivity. A promising approach to address this challenge is to prepare a porous 2D film as a selective layer of the membrane such that the film has an infinite aspect ratio. This way, challenges from pinhole defects and stacking will be eliminated. Recently, we demonstrated the synthesis of 2DZIF film with an infinite aspect ratio. It hosted a selective pore aperture made from six-membered ring (6-MR) and could successfully separate H2 from N2. However, its pore was too large for H2/CO2 separation. Zn2(bim)4 is attractive for H2/CO2 separation because it consists an extremely small pore aperture formed by 4-member ring (4-MR) along the c-axis with a crystallographic dimension of 2.1 Å . The aperture is expected to expand in the presence of guest molecules, from the flexibility of the linker to rotate (Fig. ) . In fact, the first example of 2D-MOF based membrane was demonstrated using Zn2(bim)4. In this case, membranes were prepared by stacking exfoliated nanosheets . However, these membranes could not be pressurized likely due to changes in the stacked structure of the film upon pressurization. Apart from the pressurization issue, the synthesis of the Zn2(bim)4 membrane follows a lengthy multistep approach. Briefly, its precursor (ZIF-7, phase I) is synthesized in an organic solvent at high temperatures(69). This is followed by a hydrothermal process that converts it into the lamellar Zn2(bim)4 . Nanosheets are obtained by exfoliating the lamellar precursor . A coating suspension is prepared. Finally, membranes are prepared by stacking nanosheets.