Design of Adsorption‒Diffusion Dual‐Driven MOF Membranes for Efficient CO ₂ Separation

Abstract

Abstract Metal–organic frameworks (MOFs) offer exceptional tunability in pore structure and functionality, holding considerable potential for advanced gas separation membranes. However, their advancement is restricted by the permeability–selectivity trade‐off and inefficient empirical screening. Herein, we propose an adsorption–diffusion dual‐driven design strategy balancing moderate CO 2 adsorption affinity (1 < α ads,HTCS  < 10) and high CO 2 diffusivity selectivity (α diff,HTCS  > 10) within a pore‐limiting diameter range of 3.8–4.4 Å. This rationale is corroborated by high‐throughput computational screening and experimental membrane performance. Three yfm ‐topology MOF membranes—CAU‐10H, CAU‐10pydc, and KMF‐1 with finely tuned pore microenvironments were synthesized, with the former two meeting the proposed criteria and KMF‐1 serving as a counterexample. As anticipated, CAU‐10H and CAU‐10pydc exceed the 2019 upper bound for CO 2 /CH 4 separation, with CAU‐10pydc exhibiting a remarkable CO 2 permeability of ∼2847 Barrer and a selectivity of 185, outperforming most state‐of‐the‐art membranes. Moreover, despite sharing the same kinetic diameter as CO 2 , C 2 H 2 exhibits 1.5 times higher adsorption affinity, resulting in a significantly lower permeability of only 39 Barrer under the same conditions. These results confirm the adsorption–diffusion dual‐driven design principle, providing both theoretical insight and practical guidance for other challenging gas separation scenarios.