Electric field-driven assembly of (110) oriented metal–organic framework ZIF-8 monolayer with high hydrogen selectivity.

• Compact and (110) oriented ZIF-8 membrane are prepared on the graphite substrate via electric-field-driven strategy. • Compact and (110) oriented ZIF-8 membrane is formed within 1 h at room temperature in the electric field. • The oriented ZIF-8 membrane displays high hydrogen selectivity due to the reduction of inter-crystalline defects. • At 100 ℃ and 1 bar, the separation factors of H 2 /CO 2 , H 2 /CH 4 and H 2 /C 3 H 8 are 49.5, 90.9 and 121.8 for the ZIF-8 membrane. Metal-organic framework (MOF) membranes have showed great potential in gas separation. To date, it is still a great challenge to precisely control the optimal orientation of MOF membranes with an enhanced gas separation performance. Herein, we prepared a compact and (110) oriented ZIF-8 membrane with a thickness of about 265 nm on graphite substrate within 1 h at room temperature via electric-field-driven strategy. Since the membrane is an intergrown one-crystal layer, grain boundary retardation of the flux is eliminated. Furthermore, due to the reduction of the transport pathways through the oriented structure, the (110) oriented ZIF-8 membrane exhibits a high gas separation performance. At 100 °C and 1 bar for the separation of equimolar binary gas mixtures H 2 /CO 2 , H 2 /CH 4 and H 2 /C 3 H 8 , separation factors of 49.5, 90.9 and 121.8 can be obtained, with H 2 permeance of about 1.7 × 10-7 mol·m−2·s−1·Pa−1. The developed strategy exhibits excellent reproducibility and scalability, and a large area ZIF-8 membrane can be consistently prepared on the graphite substrate, thus facilitating the preparation and application of the ZIF-8 membrane on a large scale. Further, the electric-field-driven strategy is also helpful for the preparation oriented ZIF-67 and ZIF-L membranes, confirming its versatility for the preparation of oriented MOF membranes. [ABSTRACT FROM AUTHOR]