Nitrogen-doped porous carbon nanofiber webs for efficient CO₂ capture and conversion

Nitrogen-doped (N-doped) porous carbon nanofiber webs (CNFWs) have been successfully prepared via one-step carbonization-activation treatment of pre-synthesized polypyrrole (PPy) nanofiber webs (NFWs). In this preparation process, the carbonization of the precursor and further activation with KOH were completed simultaneously. We detailedly investigated the effect of different activation conditions on the textural characteristic of final products. The resultant N-doped porous CNFWs were evaluated not only as adsorbents for CO₂ capture, but also as catalysts for CO₂ conversion, and results indicated that their textural and chemical properties can be tuned by changing the weight ratio of KOH/PPy and activation temperature. Mildly activated CNFWs (KOH/PPy = 2) obtained at 600 °C (CNFWs-600-2) exhibited relatively high CO₂ capture capacities of 6.44 and 4.42 mmol g^-1 at 0 °C and 25 °C (1 bar), respectively. Furthermore, the CNFWs-600-2 sample was also found to be metal-, solvent-, halogen-free and high-efficiency catalyst towards the cycloaddition of CO₂ to epoxides for the synthesis of cyclic carbonates. Our findings may trigger interest in studies of carbon-based materials on CO₂ capture and conversion performance.