Significant enhancement of corrosion resistance of stainless steel with nanostructured carbon coatings by substrate-catalytic CVD

The bipolar plate is the major component of proton-exchange membrane fuel cells and also a critical contributor to the fuel cell performance. Metallic bipolar plate (MBP) has high impact resistance but its poor chemical stability limits the service lifetime and stack stability. One of the feasible methods to enhance the corrosion resistance of MBPs is the formation of conductive protective coatings on the MBP surface. In this work, nanostructured carbon coatings were deposited on stainless steel by chemical vapor deposition using the substrate itself as catalysts. Under the optimized conditions, the corrosion potential of carbon coatings with dense spherical structure on stainless steel (2.1 V RHE ) is much higher than that of uncoated one (1.2 V RHE ), and even greater than that of commercial graphite bipolar plates (1.7 V RHE ), showing 75% and 23.5% improvement in corrosion resistance, respectively. Moreover, the corrosion current density of stainless steel with dense sphere-assembled coatings decreases to 0.2 mA/cm 2 , which is two orders of magnitude lower than that of graphite bipolar plates (27.4 mA/cm 2 ) at the same applied potential (2.2 V RHE ). The coated stainless steel with excellent anticorrosion properties has potential applications for MBPs in proton-exchange membrane fuel cells, electrochemical treatment of waste water, and current collectors in lithium-ion batteries.