Effect of Redox Switch, Coupling, and Continuous Polarization on the Anti-Corrosion Properties of PEDOT Film in NaCl Solution

Conjugated poly(3,4-ethylenedioxythiophene) (PEDOT) film was electrochemically synthesized on stainless steel (SS). Redox interactions between the PEDOT and SS substrate were examined in 3.5 wt.% NaCl aqueous solution with aid of electrochemical spectroscopic analyses. The results show that exhibited a barrier effect mediated oxygen reduction reaction, thus hindering ion diffusion to substrate. Localized impedance spectroscopy (LEIS) scratched area polymer shows healed defect by coupling redox reactions surface prevent charge localization concentration. electroactivity declined when polarized at potentials >−0.7 V. Prolonged exposure dissolved resulted polymer’s over-oxidation (degradation), evidenced formation carbonyl group result. degradation attributed chain scissoring due hydroxide attacks chain.