Construction of a PPIL@COF core-shell composite with enhanced catalytic activity for CO₂conversion

Converting CO₂into high value-added chemicals is a promising approach for CO₂utilization. It is imperative to develop novel catalysts for both selective and high adsorption of CO₂and thereafter efficient chemical transformation. Herein, bromide-based porous poly(ionic liquid)s (PPILs) were covalently integrated with mesoporous covalent organic frameworks (COFs) to provide a kind of core-shell hybrid for the first time. The resultant PPIL@COF hybrids fabricated by anchoring a specific ratio of PPIL to COF have a bromide per unit mass value which corresponds to the requisite CO₂uptake capacity, thereby facilitating the storage of enough CO₂around the catalytic active sites. As a proof of concept, the cyclization of epoxides with CO₂to form cyclic carbonates was selected as the benchmark reaction, the reactivity of which was significantly improved in the presence of hydroxyl group decorated PPIL@COF^Acompared to that of individual PPIL and the hydroxyl-free PPIL@COF^Bcounterpart. The hydroxyl groups at the interfacial layer, functioning as the hydrogen bond donors, cooperate with the bromides from the PPIL core to facilitate the rate-limiting step of the ring opening of the epoxides. These findings provide the basis of a novel design concept for achieving both efficient and stable catalysts in the CO₂transformation.