The synthesis of micromesoporous carbon derived from nitrogen-rich spirulina extract impregnated castor shell based on biomass self-doping for highly efficient supercapacitor electrodes

Abstract The novel impregnation of castor shell powder with nitrogen-rich spirulina extract effectively produces an infiltrated castor shell powder with KOH activator as a precursor. The prepared porous carbon exhibits nitrogen-rich micromesopores with a unique interconnected network structure and high specific surface area (1527 m2 g−1) due to the high temperature treatment of a supercapacitor electrode. Thus, the nitrogen-rich organic functional groups derived from the extract of spirulina improve the interaction of KOH and the castor shell, which is responsible for the formation of a unique interconnected micromesoporous structure. The as-prepared nitrogen doped micromesoporous carbon contributes to the increase in the charge transfer and to the decrease in the mass transfer resistance of the supercapacitor electrode. The nitrogen doped micromesoporous carbon presents a good electrochemical performance with high specific capacitance of 365 F g−1 at 1 A g−1. The charge/discharge cycling behaviour shows a loss of only 0.3% of the total capacity after 10,000 cycles at 10 A g−1. As a symmetrical two-electrode configuration, the same assembled electrode material displays a remarkable energy density of 9.14 Wh kg−1 at a power density of 500 W kg−1 and good cycling behaviour (91.7% retention of specific capacitance after 10000 cycles). Thus, the strategy of synthesizing porous carbon electrode materials mediated by spirulina extract is a promising approach for the preparation of low-cost electrode materials.