Defect‐Healed Au/rGO Coating for the Corrosion Protection of PEMFC Bipolar Plates

Proton exchange membrane fuel cells (PEMFCs) are regarded as one of the most promising types of fuel cells for next‐generation portable power applications. Stainless steel 316L is touted as a promising substrate material for bipolar plates (BPPs) due to its high machinability and ductility. In this study, a reduced graphene oxide decorated with gold nanoparticles (Au/rGO) is coated onto stainless steel 316L to enhance corrosion protection performance. Graphene oxide is reduced to reduced‐graphene oxide during the electrochemical decoration of the gold nanoparticles. The defect‐healing effect from gold nanoparticle decoration is confirmed by X‐ray diffraction, X‐ray/ultraviolet photoelectron spectroscopy and Raman spectroscopy. Electrochemical analyses to simulate the cathodic condition of the PEMFC demonstrate the improved anti‐corrosion performance of Au/rGO. After potentiostatic polarization, scanning electron microscopy and x‐ray photoelectron spectroscopy confirm that Au/rGO coating layer suppress the corrosion of the stainless steel substrate. The Au/rGO coating exhibits a corrosion current density of 2.43 µA/cm 2 and an interfacial contact resistance of 304 mΩ cm 2 . Remarkably, the amount of Fe ion dissolved from the bipolar plate is as low as 0.00612 ppm, highlighting the exceptional barrier performance of the Au/rGO coating against metal ion leaching.