Metal–organic framework (MOF) membranes have shown great potential for energy-efficient gas separation and ion separation. Ultrathin and defect-free MOF membranes are required to achieve high flux and thus reduce process costs. We have developed new seeding strategies for fabricating ultrathin and high-quality molecular sieving membranes on various porous substrates. For instance, hybrid MOF nanosheets are formed by growing MOF nanocrystals on both sides of 2D GO nanosheets. These flexible, micro-sized hybrid nanosheets allow for seeding substrates with large-pores and rough surface, eliminating substrate modification required in the conventional synthesis using nanocrystal seeds. We have further developed a novel nanocrystal-mask plasma etching method for synthesizing MOF/mesoporous GO (MOF/MGO) hybrid nanosheets. And then, a nacre-mimetic MOF membrane was fabricated by intergrowth of MOF within a preformed laminated MOF/MGO matrix via a biomimetic “assembly-and-intergrowth” approach. Due to their small thickness (about 430 nm) and well-aligned MGO nanosheets, this hierarchical structural MOF/MGO membrane exhibit excellent hydrogen molecular sieving performance with H2/C3H8 selectivity and H2 permeance as high as 2409 and 1.17×10-6 mol m-2 s-1Pa-1. In addition, the nacre-mimetic MOF/MGO membrane showed improvement of the homogeneity in mechanical deformation and fracture resistance compared with the polycrystalline MOF membrane. We have recently found that such molecular sieving membranes also have fast, selective ion permeation properties. The ion permeation results will be presented in detail.

Synthesis of ultrathin metal-organic framework membranes for gas and ion separations

255th National Meeting (2018)

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