Porous Polyimide-Based Activated Carbon Fibers for CO2 Capture and Supercapacitor

Using KOH, NaOH, and K2CO3 as activating agents, porous carbon fibers were prepared from carbonized polyimide fibers by chemical activation. The filaments could keep their fibrous morphologies after the activation of the strong bases (KOH and NaOH), which did not change the shape of the initial fiber. The nitrogen content was only 1.26-2 wt % in the activated fibers, while the oxygen content exceeded 20 wt % in K2CO3- and KOH-activated fibers. Compared with carbon fibers activated by K2CO3 and NaOH, PCF-KOH had higher values of specific surface area (1156 m(2)/g), total volume (0.54 cm(3)/g), micropore volume (0.436 cm(3)/g), and ultramicropore volume (0.283 cm(3)/ g), showing its effectiveness in the introduction of the porous structure in the carbonaceous precursor. PCF-KOH achieved the highest CO2 capacities, 6.2 mmol/g at 0 ? and 4.4 mmol/g at 25 ? (1 bar). PCF-KOH had a CO2/N-2 selectivity of 25 & SIM;31, and the value decreased with the adsorption temperature. PCF-KOH also showed the most excellent electrochemical properties, including 299.1 F/g capacitance at 1 A/g and 94% capacitance retention after 9000 cycles at 10 A/g. Carbonization and subsequent activation could thus be a facile method to fabricate polyimide-based porous carbon fibers for CO2 capture and supercapacitor.