Corrosion protection of type 304 stainless steel bipolar plates of proton-exchange membrane fuel cells by doped polyaniline coating

Polyaniline coating doped with dodecylbenzesulfonate anions is electrodeposited galvanostatically on type 304 stainless steel used as bipolar plates of proton-exchange membrane fuel cell from a basic solution of 0.3 M aniline monomer solution containing sodium dodecylbenzesulfonate as a supporting electrolyte. Electrochemical measurements in 1 M H2SO4 and in 0.3 M HCl show that the polyaniline coating increases the free corrosion potential of the steel by more than 300 mV and 450 mV, respectively, with a corrosion rate more than two orders of magnitude lower than that of the uncoated steel. Long-term exposure studies show that the coating is highly stable and inhibits the corrosion of the steel effectively.