Continuous MOFs gutter layer promoting ultrathin TFCMs for enhanced CO2 separation

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.