Anisotropic Gas Separation in Oriented ZIF‐95 Membranes Prepared by Vapor‐Assisted In‐Plane Epitaxial Growth
Xixi Ma, Zheng Wan, Yanhong Li, He Xiao, Jürgen Caro, Aisheng Huang
Abstract
Abstract Control of the microstructure grain orientation, grain boundaries and thickness are crucial for MOF membranes. We report a novel synthesis strategy to prepare highly c ‐oriented ZIF‐95 membranes through vapor‐assisted in‐plane epitaxial growth. In a mixed DMF/water vapor atmosphere, in‐plane epitaxial growth of a ZIF‐95 seeds layer was achieved to obtain an oriented and well‐intergrown ZIF‐95 membrane with a thickness of only 600 nm. Demonstrated by both experimental and simulation studies, the c ‐oriented ZIF‐95 membrane displayed superior separation performance because a perfectly oriented structure resulted in a notable reduction of intercrystalline defects and transport pathways. For the separation of equimolar binary mixtures at 100 °C and 1 bar, the mixture separation factors of H 2 /CO 2 and H 2 /CH 4 were 32.2 and 53.7, respectively, with an H 2 permeance of over 7.9×10 −7 mol m −2 s −1 Pa −1 , which was 4.6 times higher than that of a randomly oriented ZIF‐95 membrane.