Binary‐Cooperative Ultrathin Porous Membrane for Gas Separation

Abstract The construction of ultrathin porous membranes with stable structures is critical for achieving efficient gas separation. Inspired by the binary‐cooperative structural features of bones and teeth—composed of rigid hydroxyapatite and flexible collagen, which confer excellent mechanical strength—a binary‐cooperative porous membrane constructed with gel‐state zeolitic imidazolate frameworks (g‐ZIFs), synthesized using a metal‐gel‐induced strategy, is proposed. The enlarged cavity size and flexible frameworks of the g‐ZIF nanoparticles significantly improve gas adsorption and diffusion, respectively. After thermal treatment, the coordination structures forming rigid segments in the g‐ZIF membranes appear at the stacked g‐ZIF boundaries, exhibiting a higher Young's modulus than the g‐ZIF nanoparticles, denoted as the flexible segments. The g‐ZIF membranes demonstrate excellent tensile and compression resistances, attributed to the effective translation of binary‐cooperative effects of rigidity and flexibility into the membranes. The resulting dual‐aperture structure, composed of g‐ZIF nanoparticles surrounded by nanoscale apertures at the boundaries, yields a membrane with a stable CO 2 permeance of 4834 GPU and CO 2 /CH 4 selectivity of 90 within 3.0 MPa.