Corrosion protection of carbon steels by electrochemically synthesized V-TiO₂/polypyrrole composite coatings in 0.1 M HCl solution

Polypyrrole (PPy) composite coatings have been effectively synthesized in the presence of TiO₂ and V-TiO₂ nanoparticles on carbon steel by electrochemical method in aqueous oxalic acid solutions. These coatings were characterized by different surface analysis methods. TEM results confirmed that the size of V-TiO₂ nanoparticles (11.91 ± 1.03 nm) was smaller than that of TiO₂ nanoparticles (17.22 ± 2.84 nm), therefore increasing the interaction between PPy composite coatings and metal surface. The electrical conductivity measurement was carried out to examine the electrical properties of TiO₂/PPy and V-TiO₂/PPy composite coatings. Besides, the electrochemical behaviors of these coatings were also studied in 0.1 M HCl solution by electrochemical impedance spectroscopy and potentiodynamic polarization measurements. Results showed that the V-TiO₂/PPy composite coatings exhibited better anti-corrosion performance than TiO₂/PPy composite coatings. The exceptional anti-corrosion performance of PPy composite coatings was associated with the synergistic effect of the increase in physical barrier, prevention of charge transport by TiO₂ nanoparticles and the complex passive film on the metal surface.