Polyacrylonitrile-Derived N-Doped Nanoporous Carbon Fibers for CO₂ Adsorption

Carbon dioxide (CO2) capture and storage is a fundamental global environmental issue that has driven researchers to develop ingenious strategies to overcome this issue. Herein, N-enriched nanoporous carbon fibers were prepared from commercially available polyacrylonitrile fiber through a one-pot simultaneous carbonization/activation strategy. The effect of the amount of the activating agent and carbonization temperature on the nanoporous/surface chemical properties of carbons and the consequent CO2 adsorption performance was fully investigated. This direct activating strategy protected the fiber morphology of the resulting nanoporous carbons, while also resulting in a well-developed porous structure. The as-prepared nanoporous carbon fiber shows the maximum Brunauer–Emmett–Teller surface area and total pore volume of 2330 m2 g–1 and 1.25 cm3 g–1, respectively, together with a nitrogen content of up to 14.36 wt %. The optimal nanoporous carbon fiber exhibited CO2 uptakes of 6.16 and 4.03 mmol g–1 at 1 bar and 0 and 25 °C, respectively, with an acceptable CO2/N2 selectivity of 23. Besides, the optimal sample depicts a dynamic CO2 capture capacity of 0.84 mmol g–1 and only a 3% CO2 uptake capacity loss after five adsorption–desorption cycles. Overall, the combined effect of narrow microporosity and nitrogen functionalities determined the CO2 uptake of this series of N-doped nanoporous carbon fibers.