Effect of nitrogen doping on the electrochemical performance of resorcinol-formaldehyde based carbon aerogels as electrode material for supercapacitor applications

Nitrogen doped resorcinol/formaldehyde carbon aerogels with controlled nitrogen content are synthesized by controlling the resorcinol/melamine molar ratio (R/M) during the synthesis of aerogel precursors. The carbons were used as electrode materials in an electrochemical capacitor using 6 M KOH solution as electrolyte. All samples exhibited amorphous structure with low degree of graphitization. The maximum specific capacitance of 208 Fg(-1) was observed after doping of the carbon with nitrogen at R/M = 80. Drop in solution and charge transfer resistances from 0.570 to 0.150 and 0.050-0.040 was also observed respectively, with the drop in contact angles from 123 to 103 for the carbon doped with nitrogen at R/M = 80. BET results showed that the pore volume and surface area of carbon increase after N-doping, with a BET surface area of 841 m(2) g(-1) at RIM = 80. This R/M ratio is an optimum ratio at which incorporation of nitrogen into the carbon matrix improves the capacitive performance of cell as a result of improved porosity/wettability/conductivity/active sites of the electrode. Doping at higher nitrogen concentrations (RIM <80) decreased the specific capacitance of the cell significantly due to decreased conductivity of carbon and suppression of the hopping rate of dopant. (C) 2019 Elsevier Ltd. All rights reserved.