Encapsulation of ZIF-8 within a triazine ion polymer using edge 2-methylimidazole directing effect for enhancing CO2 fixation into cyclic carbonates via synergistic catalysis

Abstract

Core-shell hybrid materials have attracted attention for CO₂ capture and conversion because they overcome limitations such as low activity and poor stability of a single component. However, their synthesis is challenging because of complex conditions and required chemical structure customization between core–shell components. In this study, a series of core–shell structured metal–organic frameworks hybrid catalysts ZIF-8@IPs-x (x = 1, 2, 3, and 4) were synthesized by encapsulating ZIF-8 within a triazine ionomer polymer. Unlike previous methods that required specific functionalized directing groups (e.g., H₂, OH, or CHO) to form the core–shell structure, this approach utilized the incomplete coordination of 2-methylimidazole in ZIF-8 as a guiding agent, promoting the outer edge growth of the ionomer shell and achieving uniform encapsulation of ZIF-8. Significantly, the synergistic catalytic effects between the ZIF-8 core and the ionomer shell of the hybrid catalyst enabled efficient conversion of CO₂ into various cyclic carbonates within 3 h, without the need for solvents or co-catalysts. Furthermore, this core–shell structured catalyst exhibited facile recovery and maintains its catalytic activity over five consecutive cycles.