Abstract
In order to effectively utilize organic matter in sewage sludge (SS), a new porous carbon material was successfully prepared from SS with deep eutectic solvents (DES) (boric acid and urea), in which DES was firstly used to solvent to separate organic matter, also playing the role as a B and N donor as well as acid activator to form porous B, N-carbons. As-synthesized B, N-carbon electrode materials possessed a high specific capacitance of 251.4 F/g at a current density of 1 A/g. It retained 84.28% of the capacitance at an ultrahigh current density of 5 A/g. The energy density was 9.502 Wh/Kg at a power density of 245.4 W/kg in 6 M KOH in symmetric supercapacitor.
•Sewage sludge as feedstock for B, N-doped carbons as electrodes in supercapacitors.•Deep eutectic solvents (boric acid and urea) to separate organic matter from sewage sludge.•B, N-carbon exhibiting excellent specific capacitance (251.4 F/g, current density 1 A/g).•Excelling energy density (9.502 Wh/Kg) at 245.4 W/Kg power density in 6 M KOH.•84.28% capacitance retention at an ultrahigh current density of 5 A/g.