New insights in the anticorrosive performance of MoO42--doped PPy conductive polymer on iron in 3% NaCl solution

The article investigates the superior anticorrosive performance of molybdate-doped polypyrrole (PPy) conductive polymer coatings on iron when exposed to a 3% NaCl solution. It begins by discussing the established effectiveness of conductive polymers, particularly PPy, in providing corrosion protection for various metals, including low-carbon steel. The study emphasizes the anodic passivation mechanism, where the oxidative capability of PPy shifts the metal's potential into a passive region, forming a protective oxide film. The research builds on previous work by Deslouis et al., which demonstrated the long-term protective effects of PPy films on steel in saline environments, attributing this protection to the formation of a ferric oxalate layer under the PPy film. The current study introduces molybdate (MoO42-) as a dopant in PPy coatings, significantly enhancing their corrosion protection properties. The electropolymerization process of PPy and PPy/MoO42- coatings is detailed, highlighting the morphological and elemental composition analyses conducted using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The article delves into the self-healing capabilities of molybdate-doped PPy coatings, exploring how these coatings can repair small defects and maintain their protective integrity over extended periods. Electrochemical impedance spectroscopy (EIS) and open-circuit potential (OCP) measurements are employed to assess the anticorrosion performance of the coatings, revealing the enhanced durability and protective mechanisms of molybdate-doped PPy. The study concludes by underscoring the potential of molybdate-doped PPy as a sustainable and effective anticorrosion coating, offering a promising alternative to traditional, environmentally harmful coatings.