Electrosynthesis of homogeneous and adherent polypyrrole coatings on iron and steel electrodes by using a new electrochemical procedure

A single-step electropolymerization of pyrrole (Py) on iron and steel surfaces has been performed in aqueous medium in the presence of malate (C4H4O52−) as supporting electrolyte. The malate counter-ion slows down the iron dissolution by leading to the formation of a passivation layer on the working electrode surface, and the Py electropolymerization starts on. The polypyrrole (PPy) films electrosynthesized under different electrochemical techniques are uniform and adherent. The polymer coatings performed galvanostatically have a cauliflower-like structure and are thicker than those obtained by potentiodynamic mode. The adherence of PPy layers to the iron electrodes was estimated at 100% according to the standard sellotape test. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) analysis showed that the obtained coatings have the same structure and morphological properties as those electrodeposited on Pt electrodes.