Metal-organic frameworks (MOFs) have immense potential as sorbents and inorganic membranes for CO₂ separation. However, the trade-off between selectivity and adsorption capacity or permeability remains a challenge. Here, we present the fabrication of MOF core-shell particles and dual-layer membranes that show enhanced CO₂/N₂ separation performance compared with individual MOF materials. A highly selective MOF layer with narrow pore size is grown on the surface of a highly permeable MOF layer with large pore size. Chemical binding at the interface between the two MOFs makes it possible to form a continuous defect-free shell layer on the surface of the core or base layer. The two dual-layer MOF@MOF membranes, SIFSIX-3-Ni@SIFSIX-1-Cu and SIFSIX-3-Ni@HKUST-1, represent the first examples of pure inorganic membranes constructed from different MOFs with lattice mismatch. The CO₂/N₂ selectivity of the HKUST-1 and SIFSIX-1-Cu membranes is improved from 5.7 to 13.4 and 2.3 to 7.4, respectively, after the growth of a selective layer of SIFSIX-3-Ni.

金属有机骨架（MOF）作为吸附剂和无机膜用于CO ₂分离具有巨大潜力。然而，选择性与吸附能力或渗透性之间的权衡仍然是一个挑战。在这里，我们介绍了MOF核-壳颗粒和双层膜的制造，它们显示出增强的CO ₂ / N ₂与单个MOF材料相比的分离性能。在具有大孔径的高渗透性MOF层的表面上生长具有狭窄孔径的高选择性MOF层。在两个MOF之间的界面处的化学键合使得可以在芯层或基础层的表面上形成连续的无缺陷外壳层。两种双层MOF @ MOF膜SIFSIX-3-Ni @ SIFSIX-1-Cu和SIFSIX-3-Ni @ HKUST-1，代表了由具有晶格失配的不同MOF构成的纯无机膜的第一个示例。在生长出SIFSIX-3-Ni选择性层之后，HKUST-1和SIFSIX-1-Cu膜的CO ₂ / N ₂选择性分别从5.7提高至13.4和2.3至7.4。