Corrosion protection of polypyrrole films doped with 3-nitrosalicylate on zinc substrates.

Using 3-nitrosalicylic acid (3Nisa) as the dopant and pyrrole as the monomer, Ppy/3Nisa coatings were successfully electrodeposited on zinc substrates by a simple one-step electrochemical process. SEM analysis and FT-IR and Raman spectroscopy confirmed the successful formation of compact and homogeneous Ppy/3Nisa films on the Zn surface. Electrochemical studies demonstrated that the incorporation of 3Nisa significantly improved the corrosion resistance of Zn in a 3.5 wt% NaCl solution. The optimized coating (Z3) exhibited the lowest corrosion current density of 1.47 µA cm-2 and a corrosion inhibition efficiency of 98.6%. Open circuit potential measurements showed that the coated Zn substrates remained in the passive region for extended immersion times, while cyclic voltammetry revealed the stable redox behavior of the Ppy/3Nisa films, lasting for approximately 500 h. Electrochemical impedance spectroscopy and salt spray tests further confirmed the enhanced barrier properties and structural stability of these coatings. The improved anticorrosion performance was attributed to the dense coating structure, Zn-N/Zn-O interactions, and controlled release of 3Nisa dopant anions, which promoted the self-healing and in situ repassivation of the Zn surface. These findings suggest that Ppy/3Nisa coatings are promising materials for corrosion protection and potential Zn-based energy storage applications.