Enhancing the Performance of Supercapacitor Activated Carbon Electrodes by Oxidation

Oxidation of activated carbon (AC) with nitric acid was carried out, and the resulting AC/HNO
₃
showed high capacity when used as supercapacitor electrode material operated in the KOH electrolyte. Oxidation caused different structural changes in the AC, reducing the specific surface area and the total pore volume. After oxidation, the content of all types of oxygen-containing groups and, especially, carboxyl groups showed a significant increase. Despite the significant reduction of the specific surface area, the specific capacitance of the oxidized AC in symmetric supercapacitor electrodes is 1.4 times larger than that for the pristine AC.