Anti-corrosion and conductivity of the electrodeposited graphene/polypyrrole composite coating for metallic bipolar plates

A polypyrrole/graphene composite coating was directly electrodeposited on 304 stainless steel by cyclic voltammetry technique from a solution of pyrrole and graphene. The structure and morphology of the composite were characterized by a combination of Infrared spectrometer, Raman spectroscopy, and scanning electron microscopy. The typical characteristic peaks of graphene are detected in the composite, conforming with the successful doping of graphene. The corrosion of the composite was investigated in the environment of a proton exchange membrane fuel cell, and its performance was compared to that of a single polypyrrole coating and substrate. The composite coating enhances the corrosion resistance of the substrate more effectively than the single polypyrrole coating, as it deceases corrosion current density of substrate and maintains a high open-circuit potential throughout the whole immersion. Furthermore, the composite coating possesses higher chemical stability and better conductivity than polypyrrole coating. This is mainly attributed to the structure of composite containing graphene, which has good conductivity and is corrosion resistant. Therefore, the composite coating is a promising candidate coating for metallic bipolar plates.