New insight into the heteroatom-doped carbon as the electrode material for supercapacitors

Heteroatom-doped carbon with 4.06% of nitrogen and 10.42% of oxygen was synthesized by pyrolysis of ortho-aminophenol/formaldehyde resin. After high temperature hydrogen reduction, 2.22% of the surface oxygen was removed while the nitrogen content remained almost no change. The specific surface area enlarged from 90   m 2   g −1 to 226   m 2   g −1 and abundant micropores appeared. But we found that the specific capacitance of the reduced carbon as electrode for supercapacitors was decreased nearly 25 %. By measuring the conductivity, surface wettability, and electrochemical impedance, we proposed that (a) surface oxygen played an important role in the capacitive performance, especially the pseudocapacitance; (b) though the doped-oxygen reduced the electronic conductivity, on the other hand, enhanced the surface wettability and ion diffusion rate of the carbon electrodes.