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

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. (C) 2016 Elsevier B.V. All rights reserved.