Highly porous N-doped carbons production from biomass for high-performance supercapacitors without chemical nitrogen-containing dopants

Porous N-doped carbons were successfully synthesized via a facile and eco-friendly nitrogen-doping route without N-containing chemical dopants, where bean dregs natural N dopant instead of hazardous chemical reagents. Through co-pyrolysis and activation of rice husk and bean dregs at different mass ratios of RH and BD (1:0, 2:1, 1:1, 1:2, 1:0), a series of carbon materials were fabricated. The physicochemical properties and capacitive performance of carbon were investigated. RBAC-3 displayed superior capacitive performance. The capacitance reached 319 F g−1 at 0.2 A g−1 using two-electrode system. The capacitance retention is as high as 92.6% after 10,000 cycles. The corresponding energy density reached 15.3 Wh kg−1, increased by 37% in comparison of pure rice husk-based electrode in 6 M KOH electrolyte. That result was ascribed to the best synergistic effects of hierarchical porous structure and particular nitrogen content, suggesting a promising electrode fabrication for high-performance supercapacitors.