The implementation of mixed matrix membranes (MMMs) for sub-angstrom scale gas separations remains a grand challenge. Herein, a series of analogous mixed matrix membrane (AMMMs) were constructed via molecular-level hybridization by utilizing a reactive ionic liquid (RIL) as the continuous phase and graphene quantum dots (GQD) as nanofiller for sub-angstrom scale ethylene/ethane (0.416 nm/0.443 nm) separation. With a small number of GQDs (3.5 wt%) embedded in GQD/RIL AMMMs, ethylene permeability soared by 3.1-fold, and ethylene/ethane selectivity simultaneously boosted by nearly 60 % and reached up to 99.5, which outperformed most previously reported state-of-the-art membranes. Importantly, the interfacial pathway structure was visualized and their self-assembly mechanism was revealed, where the non-covalent interactions between RIL and GQDs induced the local arrangement of IL chains to self-assemble into plenty of compact and superfast interfacial pathways, contributing to the combination of superhigh permeability and selectivity.
Keywords: graphene quantum dots; interfacial pathways; ionic liquids; mixed matrix membranes; molecular-level hybridization.
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