Nitrogen-rich porous poly(ionic liquid)s for efficient CO2 conversion under mild conditions

Poly(ionic liquids) (PILs) offer many inherent advantages in material design, owing to their tunable structure, polarity, and versatile functionalization capability. These properties make PILs highly promising candidates for heterogeneous catalysis, especially carbon dioxide (CO 2 ) conversion and utilization. In this work, a triazine-functionalized isocyanate monomer and an amino-functionalized imidazolium-based PIL were designed and synthesized. Through the addition polymerization, a family of novel urea- and triazine-functionalized porous PIL heterogeneous catalysts (denoted as p-PIL-x) were prepared. The resulting materials were thoroughly characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and CO 2 adsorption measurements. The catalysis evaluation revealed that p-PIL-x promotes efficient CO 2 conversion via intramolecular synergy among the urea, triazine, and imidazole motifs, all of which are rich in nitrogen species. Under optimized conditions (0.1 MPa, 80 °C, 24 h), the catalyst achieved a cyclic carbonate yield of 94.33% with 99% selectivity. The reaction mechanism was further elucidated through density functional theory (DFT) calculations and in situ FT-IR measurement, which highlighted the cooperative role of hydrogen-bond donors and bromide ions in activating both the epoxide substrate and CO 2 . The synthesized p-PIL-x catalyst exhibits excellent heterogeneity, stability, and recyclability, offering a promising platform for the development of multifunctional heterogeneous catalysts toward efficient and sustainable CO 2 conversion.