Continuous interface-coupled COF-MOF membranes for precise CO₂/N₂ gas sieving

Composite membranes, which consist of a multi-layer membrane structure comprising an ultra-thin dense separation layer and a porous support layer, are used for gas separation. However, issues such as poor adhesion between layers often arise. In this study, a novel reverse-induced diffusion method was employed to achieve the in situ growth of a covalent organic framework COF (TaPa-1) on one side of polyacrylonitrile (PAN) at room temperature, resulting in the formation of a tightly bonded gutter layer. Subsequently, a metal-organic framework MOF (NH 2 -ZIF-8) was secondarily grown in situ on the TaPa-1 membrane to prepare a PAN/COF-MOF composite membrane with stable interlayer bonding. The TaPa-1 layer, with high gas permeability, and the NH 2 -ZIF-8 layer due to sheltering effect, with high gas selectivity, act synergistically to enable efficient gas sieving and rapid transport. When treating simulated flue gas (CO₂/N₂ = 1:4), the gas separation selectivity of the PAN/COF-MOF composite membrane reach 29.9, with a CO₂ permeability of 825 GPU, achieving excellent CO₂ separation performance. In this study, the PAN/COF-MOF composite membrane is constructed using the reverse-induced diffusion method, achieving stable interlayer bonding and synergistic separation, demonstrating excellent CO₂ permeability and selectivity.