High Electrochemical Performance from Oxygen Functional Groups Containing Porous Activated Carbon Electrode of Supercapacitors

Carbon electrode materials for double layer capacitors have attracted much attention, due to their low cost and abundant sources. Their low specific capacitance, however, hinders the development of carbon electrode materials. In this paper, the large specific surface area commercial activated carbons, rich in micropores, were initially oxygen-functionalized by treatment using concentrated H2SO4, saturated (NH4)2S2O8, and H2SO4/(NH4)2S2O4 mixed oxidants, respectively. The as-prepared samples were analyzed using N2 adsorption/desorption isotherms, X-ray photoelectron spectroscopy, and Boehm titration, and used as electrode materials for supercapacitors. Characterization results displayed that the oxidation treatment decreased the specific surface area along with increasing oxygen content. The electrode test showed that the electrochemical activity increased as oxygen content increased. The result that oxygen-functionalized activated carbon, even with a lower specific surface area but much more oxygen content, had higher capacity than pristine activated carbon, tells of the critical role of oxygen functional groups. The excellent capacitive performance suggests a good potential for oxygen functional carbon material to be a highly promising electrode material for supercapacitors.