Electrochemical characterization and equivalent circuit modeling of single-walled carbon nanotube (SWCNT) coated electrodes

Abstract

Single-walled carbon nanotube (SWCNT) coated electrodes are fabricated from functionalized suspensions with different pH values. Their electrochemical properties are characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The effects of the pH value of the suspension on electrochemical performances are investigated through examining the microstructures of the SWCNT films and their BET specific areas and pore volume and size distributions. Both these specific areas and pore size distributions are found being important in determining the specific capacitances of SWCNT coated electrodes. An equivalent circuit model is developed for these electrodes using the measured electrochemical impedance data. It is found that the functionalized nanotube suspensions with higher pH values produce more desirable nanostructured electrodes with the increased specific capacitance and reduced electrode resistance. The role of the pseudo-capacitance which arises from the functionalization group is also discussed.