Sweet aqueous solution for electrochemical synthesis of polypyrrole Part 1-A. On non-ferrous metals

The electrosynthesis of polypyrrole (PPy) has been achieved on aluminum electrode in aqueous medium of 0.1 M saccharin sodium salt and 0.5 M pyrrole. Scanning electron microscopy shows that the PPy coating obtained in galvanostatic and potentiostatic modes starts with small islands at weak applied potentials or current densities. Moreover, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) reveal a good homogeneity of the film achieved in cyclic voltammetry during 10 cycles. The electrochemical impedance spectroscopy (EIS) results show that the coating decreases the polarization resistance of the aluminum electrode. The open circuit potential (OCP) and dc polarization measurements achieved in HCl and NaCl solutions displayed a large positive displacement of corrosion potential and a reduction of corrosion current in the case of PPy coating electrode in comparison with electrode bare. (c) 2005 Elsevier Ltd. All rights reserved.