Quaternarized chitosan nanofiber and ZIF aerogel composites for synergetic CO₂ cycloaddition catalysis

Chemical upcycling of CO₂, a major greenhouse gas, is attracting significant attention as a crucial strategy to combat global warming. The production of cyclic carbonate using metal-organic frameworks and their composites using nanofibrous carbohydrate polymer are promising ways to convert CO₂ into valuable products. However, the current role of fibrous polymers is restricted to serving as physical substrates. This study seeks to expand the functionality of quaternarized chitosan nanofibers into synergistic catalysts in addition to their physical support role. A novel aerogel composite using Co/Zn-ZIF catalyst and quaternarized chitosan nanofiber (Q-CsNF⁺) was fabricated, and its hierarchical pore structure was extensively discussed. The obtained ZIF/Q-CsNF⁺ composite can synergistically convert epoxide to cyclic carbonate by acting as a co-catalyst. Moreover, we determined the predominant factors influencing catalytic activity in CO₂ cycloaddition, especially by examining the interplay between CO₂ affinity and co-catalyst effects. This research provides fundamental insight into developing CO₂ cycloaddition catalysts using nature-derived fibrous polymers, opening new avenues for sustainable and efficient CO₂ utilization.