One-step large-scale fabrication of nitrogen doped microporous carbon by self-activation of biomass for supercapacitors application

This paper reports a celery-derived nitrogen doped microporous carbon fabricated by a one-step self-activation method. The fabricated samples inherit the developed water transport system in biological tissue of celery, and exhibits hierarchic porous structure with opened micropores, which specific surface area reaches up to 1186 m(2) g(-1), and the average micropore diameter arrives 0.94 nm. The nitrogen heteroatoms doping enhances the wettability, conductivity and surface activity of the fabricated samples, improves the electrolyte accessibility in micropores, and thus induces superior capacitive performance. The capacitance of the fabricated samples reaches up to 245 F g(-1). Meanwhile, the device capacitance of the assembled coin-type symmetric supercapacitors reaches 54.0 F g(-1), over 93.1% of initial capacitance is retained as the current density improves from 0.5 to 20 A g(-1), and no apparent decline for initial capacitance is observed after 5000 times charge/discharge cycles, illuminating the superior charge storage capability, excellent rate capability and perfect cycle performance of the celery-derived nitrogen doped microporous carbon. In consideration of the huge yield of celery all over the world, the celery-derived nitrogen doped microporous carbon with high specific surface area and superior capacitive performance is expected to be a sustainable large-scale substitution for commercial activated carbon.