To characterize the crystal structure of the film material, the film was peeled off from the substrate, and crushed to a powder. Analysis of this powder by X-ray diffraction (XRD) shows other peaks expected with the structure of Zn2(bim)4 (Fig. ). Following Rietveld refinement confirmed that the as-prepared film is indeed Zn2(bim)4 (Supplementary Fig. ). Based on this and the SAED data, it can be confirmed that the Zn2(bim)4 film is c-oriented with its 4-MR pore aperture parallel to the substrate and perpendicular to the direction of molecular transport (Fig. ) which is attractive for membrane-based H2/CO2 separation.