Engineering interfacial transport channels in hybrid membranes via size-tunable MOF nanosheets for efficient aromatics/alkanes pervaporation separation

The energy-efficient separation of chemically similar aromatic/alkane mixtures is pivotal for modern molecular refining, yet polymeric membranes are perennially constrained by the permeability-selectivity trade-off. To circumvent this bottleneck, we report an interfacial engineering strategy utilizing size-tunable MOF (Cu-TCPP, TCPP: tetrakis (4-carboxyphenyl)porphyrin) nanosheets to engineer selective interfacial transport channels in hybrid membranes. By modulating the reaction time, the size-to-thickness ratio of the nanosheets was precisely regulated. Crucially, the sub-nanopores (0.38 nm) of Cu-TCPP preclude transport through intrinsic pore channels, thereby indicating that molecular transport preferentially occurs through MOF-polymer interfacial regions. This architecture establishes a synergistic mechanism of geometric exclusion and facilitated transport. Our results reveal that the extended diffusion pathways, dictated by the lateral sizes of the 2D nanosheets, significantly enhance geometric exclusion for n -heptane. Meanwhile, the abundant MOF active sites provide low-resistance transport channels for toluene through preferential interaction. Consequently, at an ultralow loading of 0.1 wt%, the optimized membrane achieved an exceptional flux (1170 g m −2  h −1 ) and a separation factor (6.17) for a toluene/ n -heptane mixture, with robust stability over 160 h. This work provides an effective approach for exploiting 2D nanomaterials to engineer interfacial transport channels for challenging molecular separations.