Bioinspired Design of a Giant [Mn₈₆] Nanocage‐Based Metal‐Organic Framework with Specific CO₂ Binding Pockets for Highly Selective CO₂ Separation

Abstract

Adsorption-based removal of carbon dioxide (CO₂ ) from gas mixtures has demonstrated great potential for solving energy security and environmental sustainability challenges. However, due to similar physicochemical properties between CO₂ and other gases as well as the co-adsorption behavior, the selectivity of CO₂ is severely limited in currently reported CO₂ -selective sorbents. To address the challenge, we create a bioinspired design strategy and report a robust, microporous metal-organic framework (MOF) with unprecedented [Mn₈₆ ] nanocages. Attributed to the existence of unique enzyme-like confined pockets, strong coordination interactions and dipole-dipole interactions are generated for CO₂ molecules, resulting in only CO₂ molecules fitting in the pocket while other gas molecules are prohibited. Thus, this MOF can selectively remove CO₂ from various gas mixtures and show record-high selectivities of CO₂ /CH₄ and CO₂ /N₂ mixtures. Highly efficient CO₂ /C₂ H₂ , CO₂ /CH₄ , and CO₂ /N₂ separations are achieved, as verified by experimental breakthrough tests. This work paves a new avenue for the fabrication of adsorbents with high CO₂ selectivity and provides important guidance for designing highly effective adsorbents for gas separation.