Nanoporous Polymers Incorporating Sterically Confined N-Heterocyclic Carbenes for Simultaneous CO₂ Capture and Conversion at Ambient Pressure

Postcombustion CO₂ capture and the conversion of captured CO₂ into value added chemicals are integral part of today's energy industry mainly due to their economic and environmental benefits arising from the direct utilization of CO₂ as a sustainable source. Sterically confined N-heterocyclic carbenes (NHCs) have played a significant role in organocatalysis due to their air-stability, super basic nature, and strong ability to activate and convert CO₂ gas. Here, we report a new class of nanoporous polymer incorporating sterically confined N-heterocyclic carbenes (NP-NHCs) that exhibit exceptional CO₂ capture fixation efficiency of 97% at room temperature, which is the highest ever reported for carbene based materials measured in the solid state. The NP-NHC can also function as a highly active, selective, and recyclable heterogeneous nanoporous organocatalyst for the conversion of CO₂ into cyclic carbonates at atmospheric pressure with excellent yields up to 98% along with 100% product selectivity through an atom economy reaction by using epoxides. Narrow pore size distribution of NP-NHC also allowed us to introduce a unique substrate selectivity based on size, just like enzymes, for the corresponding epoxides. This metal-free two in one approach for the CO₂ gas fixation/release and conversion provides a new direction for the cost-effective, CO₂ capture and conversion processes.