Durable degradation resistance of graphene coated nickel and Monel-400 as bi-polar plates for proton exchange membrane fuel cell

Abstract

Degradation/corrosion of metallic bi-polar plates in proton exchange membrane fuel cell (PEMFC) environment is a vexing problem in durable performance of PEMFCs. Graphene coatings have been demonstrated to provide robust and durable corrosion resistance in PEMFC environment, without compromising the essential criterion, i.e., high electric conductivity. Multilayer graphene coatings were deposited on nickel and a commercial Ni–Cu alloy by chemical vapour deposition technique. Time dependent electrochemical tests carried out in the simulated PEMFC environment (0.5 M H2SO4 solution) showed up to two orders of magnitude improvement in corrosion resistance of the metal substrate, and this resistance sustained for the entire test duration of 750 h. The magnitude of corrosion resistance of graphene-coated Ni was considerably superior than that for graphene-coated Monel 400 (investigated in this study) or graphene-coated Cu (reported in an earlier study). As suggested by the post-corrosion scanning electron microscopy, the graphene coatings on Ni and Monel 400 remained largely intact after long exposures to the aggressive H2SO4 solution. The durable corrosion resistance of nickel and a nickel-copper alloy due to graphene coating is attributed to the ability of nickel to develop multilayer graphene (however, the nickel-copper alloy is less efficient in developing a robust multilayer graphene).