Deposition of polyaniline on RVC electrodes: effect of substrate thickness

Polyaniline films, obtained by either chemical or electrochemical deposition on reticulated vitreous carbon (RVC), were investigated as a function of the substrate thickness. The electrochemical properties of these RVC/Pani electrodes were assessed by cyclic voltammetry and electrochemical impedance spectroscopy (EIS), whereas the morphology of the Pani films on RVC was analyzed by scanning electron microscopy (SEM). The cyclic voltammetric results revealed that the oxidation/reduction charges for electrodeposited polyaniline decrease as the RVC thickness is increased. Conversely, the charge densities for the chemically deposited films do not present a significant dependence on the substrate thickness. Two time constants, appearing in all the EIS spectra, indicate that an ohmic drop effect within the RVC substrate affects the polymer electrodeposition and the electrochemical behavior of the obtained electrodes. Therefore, an electric equivalent circuit considering the different electrochemical environments at the outer and inner RVC surfaces was proposed to analyze the EIS data.