One-step synthesis of polymer based N-doped porous carbon with enriched nitrogen content and its enhanced electrochemical properties in supercapacitors

N-doped porous carbon (N-PC) is considered as a promising candidate for electrochemical energy storage. However, the complicated multistep process is the biggest bottleneck. Here, a facile one-step strategy was employed to fabricate the N-doped porous carbon via the co-pyrolysis of urea and poly(acrylic acid- co -maleic acid) sodium salt (PAMS) without the protection of inert gas at 550 °C. When the mass ratio of urea to PAMS is 4:1, the microstructure and electrochemical properties of the as-prepared sample (N-4PC) are obviously improved compared with that of the direct carbonization of PAMS (PC). N-4PC presents salient peculiarities with much more mesopores, higher specific surface area of 181.5 m 2 g −1 far more than PC (23.6 m 2 g −1 ), and its nitrogen content is up to 10.61 at. %. In a three-electrode configuration using 6 M KOH, owing to the synergistic effect of pyridinic N, pyrrolic N and graphitic N atoms, N-4PC shows an outstanding specific capacity of 210 F g −1 far more than that of PC (93 F g −1 ) at 1 A g −1 , and a significant capacity retention rate of 79 % much higher than PC (47 %) at 20 A g −1 . Furthermore, the symmetric supercapacitor fabricated by N-4PC delivers an attractive specific capacitance of 140 F g −1 at 1 A g −1 , and 4.9 Wh kg −1 energy density when the power density is 265 W kg −1 in 6 M KOH. The equipment achieves superior cycle stability with capacity retention of 97 % after 7000 cycles at 1 A g −1 . Additionally, N-4PC also achieves great energy densities of 6.7 Wh kg −1 at the power density of 372.3 W kg −1 in 1 M H 2 SO 4 and 12.5 Wh kg −1 at the power density of 521.5 W kg −1 in 1 M Li 2 SO 4 . The fabricated nitrogen-doped porous carbon material has a great potential application prospect in energy storage equipment. Fig. 1. Schematic of the synthetic process of PC and N-4PC with its mechanism of enhanced electrochemical performance. • N-PC was prepared by facile co-pyrolysis at low temperature in air atmosphere. • N-doping tuned the porous structure of N-PC. • N-doping effectively improved the electrochemical properties of N-PC. • Polymer sodium salt is an excellent precursor to prepare porous carbon.