凯发

Zeolitic imidazolate framework (ZIF) membranes are attractive for many molecular sieving separation applications, but the fabrication of high-selectivity, high-flux ZIF membranes remains a great challenge. We have recently made significant efforts in developing new strategies for the fabrication of defect-free ZIF membranes. In particular, defect-free zeolitic imidazolate framework-8 (ZIF-8)/graphene oxide (GO) membrane with a thickness of 100 nm was also prepared using two-dimensional (2D) ZIF-8/GO hybrid nanosheets as seeds. 2D hybrid nanosheets with a suitable amount of ZIF-8 nanocrystals were essential for producing a uniform seeding layer that facilitates fast crystal intergrowth during the membrane formation. Moreover, the seeding layer acts as a barrier between two different synthesis solutions, and self-limits crystal growth and effectively eliminates defects during the contra-diffusion process. The resulting ultrathin membranes show excellent molecular sieving gas separation properties, such as with a high CO2/N2 selectivity of 7.0. This new 2D nano-hybrid seeding strategy can be readily extended to the fabrication of other defect-free and ultrathin MOF or zeolite molecular sieving membranes for a wide range of separation applications.