One-step electrodeposition of reduced graphene oxide-amorphous carbon composite coatings for proton exchange membrane fuel cell bipolar plates

In this paper, a convenient electrodeposition method is proposed to directly fabricate a reduced graphene oxide-amorphous carbon composite coating (rGO-ACC) on a 316L stainless steel substrate. The rGO-ACC coating is achieved through a one-step reduction by utilizing a choline chloride-ethylene glycol deep eutectic solvent (DES) with the dispersion of graphene oxide. The analysis results from SEM, Raman and XPS reveal that the obtained rGO-ACC coating, with layered wrinkle morphology, uniformly covers and covalently bonds to 316L stainless steel substrate. Potentiodynamic and potentiostatic polarization tests showed that the corrosion current densities of rGO-ACC coated 316L stainless steel were of the order of 10^-7 A cm⁻² in simulated proton exchange membrane fuel cells (PEMFC) working environment, indicating a significant improvement of corrosion resistance of 316L and an excellent electrochemical stability. Meanwhile, compared with the naked 316L steel, the interfacial contact resistance (ICR) of the coated stainless steel is significantly reduced due to the outstanding electrical conductivity of the coated rGO. The results manifested that deposited rGO-ACC on steel surface may be a highly promising modification method for PEMFC metal bipolar plates.