In-situ electrodeposition of conductive polypyrrole-graphene oxide composite coating for corrosion protection of 304SS bipolar plates

The enhancement in long-term corrosion resistance of conductive polymer coating is essential for the practical application, particularly to protect metallic bipolar plates in the aggressive environment of proton exchange membrane fuel cell (PEMFC). In this study, graphene oxide (GO) was introduced to polypyrrole (PPY) matrix, furthermore, PPY-GO composite coatings with different GO content were in-situ electrodeposited on 304 stainless steel (SS) bipolar plates to protect them from corrosion in the aggressive working environment. The electrochemical results imply that the conductive PPY-GO composite coatings significantly decrease the polarization current density of 304SS during potentiostatic polarization in the simulated PEMFC environment. The existence of GO in PPY matrix enhances the coatings adhesion strength and makes the diffusion pathway of corrosive species longer and more circuitous, further restricts their inward penetration. The PPY-GO coating with the optimized GO content of 1 mg mL⁻¹ in the electrodeposition electrolyte shows the best corrosion resistance among the prepared coatings. This enhanced long-term corrosion protection of the PPY-GO composite coating in comparison with the pristine PPY coating is resulting from the enhanced physical barrier and anodic protection.