Monolayer and bilayer conducting polymer coatings for corrosion protection of steel in 1 M H2SO4 solution

In this study, monolayer polypyrrole (PPY), polyaniline (PANI), and bilayer PPY/PANI, PANI/PPY coatings were deposited onto steel electrodes by electropolymerization in 0.1 M monomer and 0.3 M oxalic acid solution. Such corrosion parameters of these electrodes, as corrosion potentials, anodic Tafel constants and corrosion current densities were determined by means of current–potential curves as a function of time in 1 M H₂SO₄ solution. These findings were compared to the corrosion parameters of a bare steel electrode in the same acid solution. The monolayer and bilayer polymer coatings were characterized by the Fourier transform infrared (FTIR) spectroscopy and SEM. Bilayer coatings displayed better corrosion inhibition efficiencies than monolayer coatings. Furthermore, the PPY/PANI coatings offered superior corrosion protection than the PANI/PPY coatings.