Orientation Control of Metal–Organic Framework Membranes Through Magnetic Induced Room-Temperature Growth

Precise orientation regulation represents an important pathway for microstructure optimization and performance enhancement of metal–organic framework (MOF) membranes, which remains challenging to achieve. In this study, a magnetic field is employed to prepare Co-based zeolitic imidazolate framework-L (Co-ZIF-L) membranes with controlled orientation. The application of a magnetic field promotes the ordered migration of Co 2+ ions along the magnetic field lines and enables Co 2+ ions to orderly coordinate with ligands along the easy magnetization axis of MOF crystals, exposing the lowest energy crystal plane and promoting selective growth of MOF crystals. Resulting (200)-oriented Co-ZIF-L membrane with a thickness of ≈40 nm exhibits H 2 /CH 4 separation factor of 59.1 with H 2 permeance of 2275 GPU. This work provides a facile and efficient strategy to accurately regulate the preferred orientation of MOF membranes toward superior gas separation.