Interfacial polymerization on MOFs nanosheets gutter layer for ultrathin polyethyleneimine composite membranes toward efficient CO2 separation

Efficient CO 2 separation is pivotal to lowering the energy consumption and costs of carbon capture, utilization, and storage (CCUS), and thin-film composite membranes (TFCMs) with high permeance have emerged as a preferred solution for carbon neutrality and global climate change mitigation. Polyethyleneimine (PEI) exhibits excellent CO 2 adsorption capability owing to its unique amino structure, however, its excessive accumulation on the substrate surface and pore penetration lead to an overly thick functional layer, which significantly impairs the gas permeability of TFCMs. This work successfully developed a novel ultrathin polyethyleneimine (PEI) composite membrane based on MOFs nanosheets gutter layer via interfacial polymerization. Benefiting from the significant improvement of the surface properties of substrate by the MOFs nanosheets gutter layer, the prepared PEI functional layer exhibited an ultrathin thickness less than 135 nm with a highly ordered structure. The CO 2 permeance reached 779.6 GPU, with excellent selectivities of 59.1 for CO 2 /N 2 and 54.1 for CO 2 /CH 4 . The resulting TFCMs demonstrated excellent CO 2 separation performance, surpassing the 2008 and 2019 upper bound while maintaining long-term separation stability.‌ The study provided new insights into the precise design and controllable preparation of gas separation membranes, offering valuable reference for the industrial development of high-performance CO 2 separation membranes.