Covalent organic frameworks (COFs) are promising membrane materials due to their high porosity, ordered arrangements, and high stability. However, the relatively large pore size and complicated membrane preparation processes of COFs limit their applications in sieving small gas molecules, even at a lab scale. Herein, a multi-interfacial engineering strategy is proposed, that is, direct layer-by-layer interfacial reaction of two COFs (TpPa-SO₃H and TpTG_Cl) with different pore sizes to form narrowed apertures at the COF–COF interfaces atop a relatively large-pore COF (COF-LZU1) film. At 423 K, one fabricated 155 nm-thick ultrathin COF membrane displays H₂ permeance as high as 2163 gas permeation units (GPU) and a H₂/CO₂ selectivity of 26, transcending the 2008 Robeson upper bound. This strategy not only provides high-performance membrane candidates for H₂ separation, but also enlightens the interfacial engineering and pore engineering manipulation for other COFs, porous polymers, and their membranes.

中文翻译：

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通过气体分离的多界面工程策略制备超薄共价有机骨架膜

共价有机框架（COFs）由于其高孔隙率、有序排列和高稳定性而成为很有前途的膜材料。然而，COF相对较大的孔径和复杂的膜制备过程限制了它们在筛选小气体分子方面的应用，即使在实验室规模也是如此。_{在此，提出了一种多界面工程策略，即两种不同孔径的COF（TpPa-SO 3} H 和TpTG _Cl ）直接逐层界面反应，在顶部的COF-COF界面处形成窄孔。相对大孔的COF（COF-LZU1）薄膜。在 423 K 时，一种制造的 155 nm 厚的超薄 COF 膜显示 H ₂渗透率高达 2163 个气体渗透单位 (GPU) 和 H ₂ /CO ₂选择性为 26，超过 2008 Robeson 上限。_{该策略不仅为 H 2}分离提供了高性能的膜候选物，而且为其他 COF、多孔聚合物及其膜的界面工程和孔工程操作提供了启示。