Precise regulation of missing linkers in MOF pervaporation membranes for desalination of hypersaline waters

We report a method for the precise regulation of intracrystalline missing-linkers to control the permeability and selectivity of metal-organic framework (MOF) membranes. The method is applied for the design of stable ceramic-based MOF-801 membranes for hypersaline water treatment via pervaporation. For efficient membrane growth, an in situ nano-seeding strategy was employed to provide nucleation sites followed by surfactant posttreatment to minimize cracks. Missing-linkers are regulated in MOF-801 membranes by altering the ratio of fumarate to formic acid, which positively enhances water transport by modifying the MOF-801 structure and chemistry. Specifically, missing-linkers enhance membrane structural hydrophilicity with stronger host-guest interaction energy, resulting in faster transport with a lower energy barrier by enlarging the pore window and pore cage. The MOF-801 membranes demonstrated near-perfect salt rejection (~99.9%) and high water flux, outperforming most state-of-the-art silica, MOF, and zeolite polycrystalline membranes for the treatment of both saline and hypersaline waters. Notably, the membranes exhibited stable desalination performance, highlighting their promising application potential. This work provides a strategy for the rational design of next-generation high-performance MOF nanochannel membranes for challenging water purification applications.