The gutter layer of thin film composite membranes (TFCMs) promotes the formation of ultrathin top layers. MOFs nanosheets gutter layer is an efficient strategy for building gas separation TFCMs while suffers from such an issue that gas molecules transport between interlayer thus making it difficult to fully utilize the excellent molecule sieving ability of MOFs. In this work, both MOFs nanosheets and continuous MOFs gutter layers were constructed to prepare TFCMs for CO 2 separation. The polyamide top layer with irregular structure was formed on MOFs gutter layer by interfacial polymerization. The physical and chemical properties as well as separation performance of different TFCMs were further compared. Benefitting from the denser structure and stronger hydrophobicity of continuous ZIF-8 gutter layer, the obtained top layer showed more regular structure with ultrathin thickness (≈30 nm). At the same time, due to the ZIF-8 gutter layer provided additional and stable CO 2 selectivity, the CO 2 permeance reached 588.2 GPU with the selectivity of CO 2 /N 2 and CO 2 /CH 4 of 49.8 and 52.3, which surpassed the 2008 Robeson upper bound. We believe that such a membrane design based on continuous MOFs gutter layers is a promising approach for high-performance gas separation membranes.
Two-dimensional (2D) materials-based membranes with artificial transfer channels have shown significant potential for selective separation. However, the challenges such as uncontrollable interlayer spacing and undesirable molecular sieving capabilities of 2D channels have impeded their further application in separation. Inspired by biological selectivity transport channels with proper steric and affinity sites, herein we have designed biomimetic 2D selective transport channels based on a ZIF-L nanosheet membrane. In this design, the UiO-66-NH 2 nanoparticles tune the appropriate interlayer confinement and compensate for laminate framework defects of 2D selectivity transport channels, the artificial imprinting recognition sites establishes the essential chemical environment for specific separation. As a result, the obtained MOFs nanosheet based membranes with imprinted recognition sites (MN-IMs) exhibited enhanced permeation flux ( J = 1.0847 × 10 −3 and 1.0423 × 10 −3 mg min −1 cm −2 ) and permselectivity ( α = 3.77 and 4.10), outperforming state-of-the-art similar technologies. Besides, the composite MOFs demonstrated good photoinduced self-recovery ability, which also enables MN-IMs to have long-lasting selective separation performance (the separation efficiency is 90.76 %) in the continuous separation process. This study introduces a novel design strategy for developing sophisticated 2D materials-based membranes and offers new insights into the precise separation of specific molecules.
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