Promising nitrogen-doped porous nanosheets carbon derived from pomegranate husk as advanced electrode materials for supercapacitors

Abstract

Nitrogen-doped porous activated carbons (N-PHACs) have been successfully synthesized using pomegranate husk as carbon precursor via ZnCl2-activation carbonization and subsequent urea-assisted hydrothermal nitrogen-doping method. The obtained N-PHACs possesses abundant mesoporous structure, high specific surface area (up to 1754.8 m2 g−1), pore volume (1.05 cm3 g−1), and nitrogen-doping content (4.51 wt%). Besides, the N-PHACs-based material showed a high specific capacitance of 254 F g−1 at a current density of 0.5 A g−1 and excellent rate performance (73% capacitance retention ratio even at 20 A g−1) in 2 M KOH aqueous electrolyte, which is attributed to the contribution of double-layer capacitance and pseudocapacitance. The assembled N-PHACs-based symmetric capacitor with a wide operating voltage range of 0–1.8 V exhibits a maximum energy density of 15.3 Wh kg−1 at a power density of 225 W kg−1 and superior cycle stability (only 6% loss after 5000 cycles) in 0.5 M Na2SO4 aqueous electrolyte. These exciting results suggest that the novel N-doping porous carbon material prepared by a green and low-cost design strategy has a potential application as high-performance electrode materials for supercapacitors.