Nitrogen Self-Doped Porous Carbon for High-Performance Supercapacitors

Supercapacitor electrodes based on carbonaceous materials with hierarchical porosity and localized graphitic structure can help supercapacitors to achieve considerable energy capacity. In this work, chitosan-derived hierarchically porous graphitic carbon (CS-HPGC) with nitrogen self-doping was synthesized via a simple and green approach using potassium ferrate (K₂FeO₄). Different from conventional templating or two-step strategies, this method allows the accomplishment of carbonization, graphitization, and heteroatom modification in a one-step process. Endowed with the characteristics of hierarchical porosity, high graphitization degree, and N-doping, the CS-HPGC electrode showed a high specific capacitance of 332 F g^–1 at 0.5 A g^–1. Furthermore, the assembled CS-HPGC symmetric supercapacitors delivered an energy density of 10.2 Wh kg^–1 at the power density of 100 W kg^–1 in aqueous electrolyte (KOH) and 63.3 Wh kg^–1 at 300 W kg^–1 in ionic liquid electrolyte (EMIM TFSI). This synthetic strategy may pave the way for the development of natural and renewable biomass resources for sustainable energy systems.