Ultrathin Node‐Missing Glass Membranes Enabled by Vapor Deposition of Lattice‐Defective ZIF Nanofilms for Gas Separation

Membrane technology for gas separation is more efficient and energy-saving than thermally driven processes, including cryogenic distillation and adsorption. Metal-organic framework (MOF) and related glass membranes hold great potential for precise gas separation, but it remains challenging to construct ultrathin MOF glass membranes and optimize their transport pathways. In this study, a strategy based on vapor-linker deposition and melt-quenching is reported to design ultrathin zeolitic imidazolate framework (ZIF) glass membranes with node-missing defect passageways. Vapor-linker deposition can prepare ZIF nanofilms with lattice defects, enabling melt-quenching of ZIF glass membranes with an ultrasmall thickness of 100 nm and node-missing defects. Moreover, this study demonstrates that node-missing defects can reduce the dissociation energy barrier of coordination bonds to reduce melting temperature and serve as adsorption sites and modulators to improve preferential sorption properties and gas transport processes. For challenging CH4/N2 separation, which is critical to natural gas upgrading but energy-intensive, the ZIF glass membranes exhibit competitive performance and stability, with CH4 permeance of 100 gas permeation units and CH4/N2 selectivity up to 6.73 for binary separation, surpassing those of most state-of-the-art membranes. This study offers a viable route to obtain high-performance separation membranes and underscores the pivotal roles of molecular-level mismatch defects in glasses.