Fabrication of metal organic framework membranes via hierarchical metal-governed interfacial regulation synergy for efficient propylene/propane separation

Metal-organic framework (MOF) membranes are regarded as promising candidates for achieving excellent propylene/propane separation performance and possess the potential for industrial application. However, the complexity of regulating the growth process of MOF on substrates renders the directly preparation of defect-free films extremely challenging. Herein, we proposed a hierarchical metal governed-interfacial regulation (HMG-IR) strategy to engineer structurally optimized MOF/substrate interfaces by synergistically integrating hydroxyl-rich robust vermiculite (VMT) nanosheets, Zn²⁺ ions, and phosphate-functionalized phytic acid (PA). Pre-introduced Zn²⁺ facilitate the formation of a uniform Zn-PA coordination network via hierarchical interactions, while subsequent coordination saturation increases interfacial metallization density, thereby reducing the MOF nucleation energy barrier and guiding its epitaxial growth. Based on this targeted designed interface, a crystalline ZIF-8 membrane with remarkable properties has been fabricated through a surface-induced solution process. The optimized membrane exhibits structural integrity, a defect-free morphology and an ultrathin thickness of ∼251 nm. It demonstrates excellent C₃H₆/C₃H₈ separation performance with a C₃H₆ permeance of 141.6 GPU and C₃H₆/C₃H₈ selectivity of 40.1, coupled with outstanding long-term stability and mechanical durability. This study establishes a novel strategy for the in-situ construction of ultrathin MOF films through multi-level interfacial engineering, highlighting the pivotal role of coordinated nucleation manipulation and controlled crystal growth in overcoming traditional fabrication limitations.