Conclusion
Freestanding microporous carbon ultrafine fibers (PR-C) with outstanding CO2 adsorption performance are prepared by electrospinning from resole-type phenolic resin and subsequent one-step carbonization. High specific surface area and pore volume can be obtained through simple carbonization without activation using phenolic resin as electrospinning precursor, which is superior to the case of PAN. Importantly, PR-C possesses large amounts of ultra-small micropores with size of around 0.50–0.63 nm, which is distinct from activated PAN-based carbon nanofibers and commercial porous carbons with comparable or much higher specific surface area and pore volume. By increasing trapping sites and enhancing adsorption affinity for CO2 molecules, much more ultra-small micropores are principally responsible for larger CO2 uptake quantities of PR-C as compared to other samples. Ultrafine fibrous diffusion paths, shallow micropores and improved utilization of the overall pore structure also promote CO2 adsorption performance for PR-C. Freestanding monolithic characteristic, fine control of micropore structure, high stable adsorption capacities and outstanding recyclability make electrospun phenolic resin-based carbon ultrafine fiber a promising adsorbent for CO2 capture and storage.