Hierarchical Amino-Functionalized Ionic Liquids@MOF Composite Gel for Catalytic Conversion of CO₂

Hybridization of metal-organic frameworks (MOFs) and homogeneous ionic liquids (ILs) endows the heterogeneous composite with high porosity and accessible multiple active sites (e.g., acidic or basic sites), which exhibits great potential in CO₂ capture and conversion. Nevertheless, the majority of MOF composites are synthesized as powders, significantly restricting their practical applications due to inherent problems such as poor handling properties, high pressure drops, and mechanical instability. Thus, it is crucial to shape MOF composites into various monoliths that allow efficient processing, especially for industrial purposes. In this work, a hierarchical ILs@nanoMOF composite gel (H-IL@UiO-66-gel) featuring both intraparticle micropores and interparticle mesopores and multiple active sites was successfully fabricated by a two-step approach. Benefiting from the integrated advantages of the hierarchically porous MOF for enhanced mass transfer and affinity of ILs for activating CO₂ molecules, the resultant H-IL@UiO-66-gel exhibits excellent uptake of macromolecules and catalytic activity toward CO₂ cycloaddition with epoxides under moderate conditions, far beyond the traditional microporous IL@UiO-66-gel and unfunctionalized H-UiO-66-gel. Furthermore, the H-IL@UiO-66 composite monolith can be effortlessly separated and reused at least three times without depletion of catalytic activity. It is believed that this fabrication method for the shaping of MOF composites is highly versatile and can be extended to other types of MOFs for various application fields.