Electrochemical behavior of metallic and semiconducting single-wall carbon nanotubes for electric double-layer capacitor

Electrochemical behavior of metallic and semiconducting single-wall carbon nanotubes (SWCNTs) separated by agarose gel chromatography was analyzed as electrodes of electric double-layer capacitor (EDLC). Due to the doping of ions to semiconducting SWCNTs, the cyclic voltammogram of semiconducting SWCNTs showed amphoteric behavior, which is analogous to that of dopable conducting polymers. As the potential was increased or decreased from the flat band potential, the capacitance of semiconducting SWCNTs was increased, but that of metallic SWCNTs was slightly increased. The high capacitance of semiconducting SWCNTs at the high potential is beneficial for EDLC due to the possible limitation of capacitance.