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

•The PPy/G coating was obtained on 304SS by one-step electropolymerization.•Addition of graphene in PPy film improved anti-corrosion and conductivity.•Lamellar graphene enhanced the chemical stability of the PPy coating in PEMFC.•The presence of graphene hindered the inward penetration of corrosive species.