One-step pyrolysis toward nitrogen-doped hierarchical porous carbons for supercapacitors

Abstract

The design of nitrogen-doped hierarchical porous carbons (NPCs) with unique physicochemical properties has progressively become a pressing work on account of requirement that next-generation supercapacitors possess higher energy storage capacity. Nitrogen-doped hierarchical porous carbons are fabricated by one-step pyrolysis of chitosan hydrogels with in-situ growing hydroxyapatite templates. During the pyrolysis, the carbonization and activation can be completed simultaneously to create abundant of micropores, mesopores and macropores. Meanwhile nitrogen is introduced into the hierarchical porous carbons to boost its electrochemical properties. The optimized NPC-MHK with the high surface area of 2165.5 m2 g−1 exhibits a favorable specific gravimetric capacitance of 306.4 F g−1 and cycling stability with 93.0% of capacitance retention after 10 000 cycles in the 6 M KOH electrolyte. In addition, the assembled NPC-MHK// NPC-MHK symmetric supercapacitors are effective to support the light-emitting diodes. This simple and environmental-friendly strategy has universal significance in fabricating heteroatom-doped hierarchical porous carbons on a vast scale for advanced energy storage and conversion devices.