Fabrication of highly (110)-Oriented ZIF-8 membrane at low temperature using nanosheet seed layer

Preferred orientation represents a main concern for microstructure control and performance optimization of MOF membranes. To date, it remains a challenging task to precisely control preferred orientation of ZIF-8 membrane. Herein, we prepared highly (110)-oriented ZIF-8 membrane by oriented secondary growth. Among various elements, preparation of uniform ZIF-8 nanosheet seeds through thermal conversion of identically shaped ZIF-L precursors, spin-coating-assisted oriented deposition of (110)-oriented ZIF-8 seed layer, and controlled in-plane secondary growth at low temperature were found crucial for obtaining well-intergrown (110)-oriented ZIF-8 membrane whose H-2/CO2 ideal selectivity exceeded H-2/N-2 and H-2/CH4 under ambient conditions, owing to preferential CO2 adsorption capacity of not only PEI but also ZIF-8 nanosheets compared with their bulk counterparts. Our research highlighted the significance of preferred orientation regulation in tailoring the gas permeation behavior of MOF membranes.

Automated summary

The study demonstrated the importance of preferred orientation regulation in controlling the gas permeation behavior of MOF membranes, by achieving highly (110)-oriented ZIF-8 membrane through oriented secondary growth. Through key steps such as thermal conversion and spin-coating, the membrane's preferred orientation could be effectively controlled to enhance gas selectivity.