(293c) Electrophoretic Nuclei Assembly for Crystallization of High Performance Membranes on Unmodified Supports

Metal-organic frameworks (MOFs) films have recently emerged as highly permselective membranes yielding orders of magnitude higher gas permeance than that from the conventional membranes.^1,2 However, the synthesis of highly-intergrown, ultrathin MOF films on porous supports without complex support-modification has proven to be a challenge.³ Moreover, there is an urgent need of a generic crystallization route capable of synthesizing a wide-range of MOF structures in an intergrown, thin-film morphology. Herein, we report a novel electrophoretic nuclei assembly for crystallization of highly-intergrown thin-films (ENACT) approach, that allows synthesis of ultrathin, defect-free ZIF-8 on a wide range of unmodified supports (porous polyacrylonitrile, anodized aluminum oxide, metal foil, porous carbon and graphene).⁴ As a result, a remarkably high H₂ permeance of 8.3 x10^-6 mol/m²-s-Pa, and ideal gas selectivities of 7.3, 15.5, 16.2, 2655 for H₂/CO₂, H₂/N₂, H₂/CH₄, and H₂/C₃H₈, respectively, are achieved from an ultrathin (500-nm-thick) ZIF-8 membrane. A high C₃H₆ permeance of 9.9 x10^-8 mol/m²-s-Pa, and an attractive C₃H₆/C₃H₈ selectivity of 31.6 are obtained. The ENACT approach is straightforward, reproducible and can be extended to a wide-range of nanoporous crystals, and we demonstrate its application in the fabrication of intergrown ZIF-7 films.

References

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3. Barankova, E.; Tan, X.; Villalobos, L. F.; Litwiller, E.; Peinemann, K. V. A Metal Chelating Porous Polymeric Support: The Missing Link for a Defect-Free Metal–Organic Framework Composite Membrane. Angew. Chemie - Int. Ed. 2017, 56, 2965–2968.
4. He, G.; Dakhchoune, M.; Zhao, J.; Huang, S.; Agrawal, K. V. Electrophoretic Nuclei Assembly for Crystallization of High-Performance Membranes on Unmodified Supports. Adv. Funct. Mater. 2018, (in press), doi: 10.1002/adfm.201707427.