Highly efficient H2/CO2 separation via an ultrathin metal-organic framework membrane

We propose a strategy for rapid in situ fabrication of zeolitic imidazolate framework-8 (ZIF-8) hybrid membrane with assistance of the two dimensional (2D) graphitic carbon nitride (g-C 3 N 4 ) nanosheets at room temperature. The negatively charged g-C 3 N 4 nanosheets with abundant nitrogen coordinating sites are capable to capture and anchor Zn 2+ and thus provide a large number of heterogeneous nucleation sites for the formation of initial ZIF-8 crystals. During the cyclical spin coating of the Zn 2+ /g-C 3 N 4 nanosheets and the ligand (2-methylimidazole), the in situ formed ZIF-8 crystal nucleus on g-C 3 N 4 nanosheets promote the further growth of continues defect-free membranes. The ZIF-8/g-C 3 N 4 membrane with thickness of ∼240 nm can be obtained using this strategy within 30 min at room temperature, which is attractive for fast and facile preparation of molecular sieving membranes. Moreover, it exhibits promising H 2 /CO 2 separation performance with the selectivity up to 42, which is superior to many other ZIF-8 membranes.