Light-activated charged nanopores in gas permselective membrane

Gas permselective membranes are inherently constrained by a trade-off between permeability and selectivity. Overcoming this limitation is key to enabling broader industrial adoption, and advanced porous materials—particularly metal-organic frameworks (MOFs)—have emerged as promising candidates. Yet, to truly rival established separation technologies such as distillation, innovative design strategies remain essential. Traditionally, efforts to surpass the trade-off have focused on tuning porosity, pore architecture, chemical functionality, and macroscopic transport pathways (particle morphology). These modifications are achieved either through bottom-up synthetic approaches or by employing external stimuli such as light, pressure, or electric fields. In this work, we introduce a photo-chargeable membrane that enhances gas permselectivity through precise, molecule-specific interactions—without altering the underlying porous architecture. This is achieved by incorporating a nanoporous MOF, constructed from redox-active organic ligands, as filler in a mixed matrix membrane. Upon photoexcitation, ligand–ligand charge separation induces stable surface charges within the pores, enhancing CO₂/N₂ and CO₂/CH₄ selectivity surpassing the Robeson upper bound.