Precision Pore Engineering of COF Membranes for Advanced Gas Decarbonization

Membrane technology offers an energy-efficient approach for gas decarbonization; however, developing materials that combine high permeance with strong selectivity remains challenging. Covalent organic frameworks (COFs), characterized by high porosity and tunable pore apertures, are considered ideal candidates for high-performance gas separation membranes. Angstrom-precision membrane pore engineering enables highly efficient separation of gas molecules with subangstrom size differences through synergistic control of pore size distribution and selective binding sites. This work presents a strategic advance in COF membrane design through a facile crystallinity-enhanced interfacial stitching strategy. We report the synthesis of a highly crystalline, amine-functionalized aminal-linked COF (hcTPA-PZ COF) featuring sub-1 nm pores, which was subsequently assembled into continuous hcTPA-PZ COF layers via a rapid Schotten–Baumann reaction at the water/heptane interface. This approach yields a membrane rich in basic nitrogen sites (secondary and tertiary amines) that serve as facilitated transport carriers for CO2. The resulting membrane exhibits a CO2 permeance of approximately 1000 GPU, with gas selectivities of 33 for CO2/N2, 8 for CO2/H2, and 12 for CO2/CH4, surpassing the most previously reported COF membranes. The synergistic combination of long-range ordered channels from high crystallinity and specific CO2-facilitated transport sites establishes a paradigm for designing high-performance membranes for gas decarbonization.