Structural and electrochemical characterization of carbon electrode modified by multi-walled carbon nanotubes and surfactant

In this study, multi-walled carbon nanotubes were successfully deposited on the surface of the carbon electrode (CE) using a cationic surfactant (Cetyl Trimethyl Ammonium Bromide, CTAB) by simple electrodeposition method. FT-IR spectra, SEM images and the contact angle measurements were employed to characterize the structure of the modified electrode. The electrochemical impedance spectroscopy and cyclic voltammetry were performed to evaluate the electroanalytical behavior of electrodes through the modification process. The results indicated that the impedance of the modified electrode was reduced about 95% at pH 3 and 7.4 and 91% at pH 11 due to the deposition of the nanotubes on its surface. The equivalent circuit for EIS measurements was perfectly fitted at three pH values (3, 7.4 and 11) on the basis of the transmission line model that represents the impedance response of a diffusion process to characterize the properties of the bulk films. Also, the electrochemical behavior of methylene blue on the surface of the modified electrode was investigated. The obtained cyclic voltammograms showed three redox peaks, which can be related to the formation of semi-methylene blue and leucomethylene blue.