One-step synthesis of chitin-derived nitrogen-rich porous carbon fiber assisted with ammonium chloride chemical blowing for supercapacitors

Rich nitrogen-doped porous carbon fiber (NC–NH4Cl) was successfully prepared from chitin via environmentally friendly simple pyrolysis supplemented with ammonium chloride as a recyclable porogen and nitrogen source. Compared with NH4HCO3 and (NH4)2SO4, NH4Cl proved to be the most effective porogen and nitrogen dopant for chitin. The as-made NC–NH4Cl exhibited a 3D architecture formed by numerous intertwined microfibrils with a hierarchical micro/mesoporous structure. Moreover, NC–NH4Cl possessed a high nitrogen content of 10.0 at.%, and about 70% of the nitrogen was in the form of pyridinic-N and pyrrolic-N. The NC–NH4Cl electrode could deliver superior specific capacitance of 284 F g−1 at a current density of 0.5 A g−1, as well as favorable rate performance (ca. 66.3% retention as the current density rose from 0.5 to 20 A g−1) and long cycle life (ca. 96.9% maintained after 5000 cycles) in a three-electrode configuration. The assembled NC–NH4Cl-based symmetric capacitor presented a desirable energy density of 16.67 Wh kg−1 at 1 A g−1. The results suggest that NC–NH4Cl is a promising candidate for supercapacitors.