Metal‐Organic Framework Quasi‐Monolayer Integrated Composite Membranes for Selective Rare‐Metal Separation

Abstract Pliable integration of metal‐organic frameworks (MOFs) with polymers enables precise separations, advancing circular economy initiatives. Maximizing the pore functionality of MOFs is critical for rapid ion sieving but necessitates a uniform and stable distribution to expose their interpenetrated nanochannels. Here, this work reports a controlled approach for integrating an ultrathin Zr‐MOF monolayer with a flexible polyamide film using a coupled cathode electrophoretic deposition and interfacial polymerization (CED‐IP) strategy. By tuning the electric field intensity, this work achieves uniform monolayer coverage of diverse MOFs (UiO‐66, MOF‐808, and NU‐1000) with varying pore apertures on porous supports, followed by the formation of a thin‐film nanocomposite (TFN) configuration via confined IP. The exposed functional groups within these MOF pores enhance interaction with aqueous‐phase diamines, which polymerize with acyl chlorides, resulting in TFN membranes with a moderately reduced crosslinking degree, improved hydrophilicity and enhanced surface electronegativity. Experimental and simulation data reveal that the large‐pore NU‐1000 offers the lowest transport resistance in polyamide membranes, leading to an exceptional 186.3% increase in water permeance compared to control membranes. The resulting Zr‐MOF‐integrated polyamide membrane demonstrates outstanding selectivity for WO 4 2− /Cl − (50.6) and MoO 4 2− /Cl − (53.7), outperforming most MOF‐based nanofiltration membranes. These results underscore the potential of a mesoporous MOF‐monolayer based TFN membranes for low‐energy extraction of critical rare metals.