Electrodeposition of graphene nano-thick coating for highly enhanced performance of titanium bipolar plates in fuel cells

We report in this paper a simple method of coating very thin graphene film on titanium substrate, affording it markedly enhanced resistance to corrosion and much decreased electrical contact resistance under the environment of proton exchange membrane fuel cells (PEMFC). The graphene film is formed by electrodepositing graphene oxide (GO) on Ti sheet via normal pulse voltammetry , followed by reducing the deposited GO at 500 °C in hydrogen atmosphere. The resultant graphene film, with a thickness of only around 50 nm, evenly covers and covalently bonds to the Ti sheet, as revealed by SEM, Raman and XPS . Both potentiodynamic and potentiostatic tests of the graphene coated Ti (G/Ti) sample are conducted under simulated chemical environment and electrode potentials of PEMFC. Under all the circumstances, the corrosion currents of G/Ti sheet are in the order of 10 −7  A/cm 2 , significantly less than that of bare Ti sheet. Moreover, the coated graphene film on Ti sheet leads to a much lower and more stable interfacial contact resistance (ICR) of around 4 mΩ cm 2 . These results mean that the G/Ti sheet meets the U.S. DOE target of 2020 for PEMFC bipolar plates (BP) in terms of both the corrosion and electrical resistance. Therefore, the G/Ti sheet appears to be a very promising BP material in PEMFC.