Influence of solvent composition on the anti-corrosion performance of copper–polypyrrole (Cu–PPy) coated 304 stainless steel

Abstract

Abstract Copper–polypyrrole (Cu–PPy) was electrochemically deposited on 304 stainless steel (SS) surfaces from various compositions of water–methanol binary mixtures containing both pyrrole monomer and metal precursor using double pulse chronoamperometry. Scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) were employed to understand the morphology and composition of the Cu–PPy coated SS. The anti-corrosive performances of the modified electrodes were investigated in 0.5 M NaCl using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. We found that after 300 h of immersion period, the Cu–PPy coating prepared from a solution containing 1:4 water to methanol volume ratio exhibited a better corrosion protection to SS than coatings prepared from other compositions. This behavior was rationalized using the low permeability and enhancement in the barrier property of the Cu–PPy coatings with increase in MeOH content.