Amine‐Rich Molecular Nodule‐Assembled Membrane Having 5 Angstrom Channels for CO₂/N₂ Separation

Abstract Porous organic cages (POCs) with abundant porosity and interconnected cavities have garnered significant research attention as a distinct class of porous materials due to their potential applications in gas sorption and separation. However, the ordered arrangement of POCs to eliminate inter‐cage defects remains challenging in the assembly of molecular‐selective membranes, which greatly hinders the effectiveness of pore sieving. Here, amine‐rich molecular nodules (AMNs) are created by reduction of the porous organic cage CC2, in which the spatial structure incurs a vertex collapse into the interior of the original tetrahedral structure, which eliminates the large window of CC2. By an interfacial reaction with terephthaloyl chloride, the AMNs assemble into a cross‐linked topological network having angstrom‐scale channels for selective CO₂/N₂ separation. The AMN‐assembled membrane displays a high CO₂ permeance of 752 GPU, a CO₂/N₂ selectivity of 67 at 1 bar, as well as high‐pressure resistance, operational stability, and scalable manufacture potential, which provides a cost‐effective and practical solution for developing membranes for capturing CO₂ from industrial flue gas.