One-step synthesis of N, S-codoped porous graphitic carbon derived from lotus leaves for high-performance supercapacitors

Abstract

The development of high-performance biomass-derived porous graphitic carbon materials is in high demand for applications in supercapacitors. Herein, a novel N, S self-codoped porous graphitic carbon is synthesized by one-step carbonization of lotus leaves together with urea and ferric chloride. Due to the combination of urea as a nitrogen doping agent and ferric chloride as both activating agent and graphitization catalyst, the obtained lotus leaf–derived porous graphitic carbon material possesses a high specific surface area of 975.7 m2 g−1, appropriate pore structure with interconnected macropores, suitable graphitization level, and high N, S contents. The resultant porous graphitic carbon electrode shows a high specific capacitance of 385.0 F g−1 at 0.5 A g−1 (based on a three-electrode system in 6 M KOH electrolyte), and good rate capability (140.0 F g−1 at 100 A g−1). Furthermore, the assembled carbon-based symmetric supercapacitor delivers a high energy density of 29.5 Wh kg−1 at a power density of 545.6 W kg−1 and excellent long-term cycling stability (95.3% of the initial capacitance after 20,000 cycles at 5 A g−1). This work provides a general method to synthesize porous graphitic carbon from biomass for electrochemical energy storage and conversion.