Nitrogen-Doped Hierarchical Porous Carbon from Wheat\nStraw for Supercapacitors

Abstract

In\nthis paper, wheat straw was converted into nitrogen-doped hierarchical\nporous carbon (N-HC) by direct pyrolysis of wheat straw with CaCl₂ as an activator and melamine as a nitrogen resource. The\nas-prepared samples exhibit different hierarchical porous structures\nand nitrogen contents in a temperature range from 600 to 800 °C.\nCompared with other samples, the N-HC-800 displays a large amount\nof micropores, uniform mesopores, a high specific surface area (892\nm² g^–1), and moderate nitrogen doping\n(5.63 wt %). Therefore, the N-HC-800-based supercapacitor exhibits\na high specific capacitance of 275 F g^–1 at a current\ndensity of 0.2 A g^–1, a high capacitance retention\nratio of 81% even at 8 A g^–1, and an excellent cycling\nstability (over 97% retention rate after 10 000 cycles) in\n6 M KOH solution. This work not only proposes a novel routine for\nthe development of porous carbon materials for supercapacitor but\nalso provides a new option for the processing of waste wheat straw\ninstead of being burned in rural areas.