Chitin-Derived Poly(Ionic Liquid)s for High-Yield CO ₂ Cycloaddition

The chemical fixation of carbon dioxide (CO2) into value-added chemicals is a pivotal research direction toward achieving carbon neutrality and sustainable chemistry. Herein, a biomass-derived poly(ionic liquid) (BPIL) was designed from renewable chitin and low-cost pyridinium. The as-prepared catalyst exhibits excellent performance in the cycloaddition of CO2 with various epoxides under mild/solvent-free/cocatalyst-free conditions. Furthermore, the catalyst demonstrates remarkable stability and recyclability with no significant loss of activity over five consecutive cycles. More importantly, a combination of in situ FTIR experimental studies and density functional theory (DFT) calculations reveals a crucial synergistic effect between the hydroxyl groups on the biomass support, acting as hydrogen bond donors (HBDs), and the iodide anions. This synergy effectively activates the epoxide and significantly lowers the energy barrier of the rate-determining step. This work not only provides an efficient and green catalytic system for CO2 valorization but also offers a strategy for the rational design of multifunctional catalysts from renewable biomass.