New single-step electrosynthesis process of homogeneous and strongly adherent polypyrrole films on iron electrodes in aqueous medium

Homogeneous and strongly adherent polypyrrole (PPy) films were electrochemically synthesized on iron electrodes in sodium tartrate (Na2C4O6H4 0.2 M) aqueous solution. This one step pyrrole electropolymerization process has been successfully achieved under different electrochemical techniques, such as potentiodynamic, galvanostatic and potentiostatic modes. During the first stage of the electrochemical process the tartrate counterion slows down the iron dissolution by leading to the formation of a passivation layer on the working electrode surface, and the pyrrole electropolymerization takes place. The electrosynthesized polymer deposit has been characterized by several microscopic and spectroscopic techniques. Any iron traces have been detected by X-ray photoelectron spectroscopy (XPS) on the outer side of the PPy films, which confirms the compactness and the homogeneity of the polymeric coating. Scanning electronic microscopy (SEM) imaging showed uniform and compact PPy coatings with cauliflower-like structure. Infra-red (IR) and Raman spectroscopies proved that the obtained PPy films have the same vibrational properties as those electrodeposited on noble Pt plates. (C) 2002 Elsevier Science Ltd. All rights reserved.