Engineering MOFs for thin-film and nanofilm nanocomposite membranes for CO₂separation

Microporous crystalline metal–organic frameworks (MOFs) have been incorporated into polymers to enhance carbon capture performance due to their well-controlled pore sizes and porosity. However, MOFs may aggregate in the polymers and form interfacial voids, resulting in reduced selectivity. Such challenges are exacerbated when they are incorporated into thin-film nanocomposite (TFN) or nanofilm nanocomposite (NFN) membranes, where the effects of interfacial interactions and nanoconfinement become more pronounced in defect-free films as thin as <100 nm. To address these issues, novel MOFs have been developed to improve their distribution in thin films and their contribution to gas separation properties, such as surface functionalization, defect engineering, amorphization, and incorporation with polymers and macrocycles. We critically assess these strategies and highlight their contributions to enhancing CO₂ separation properties. Understanding the scaling and integration of these engineered MOFs in TFNs provides insights into designing next-generation membranes for molecular and ion separations.