(Invited) Development of Novel Coatings on Stainless Steel based Bipolar Plates for Proton Exchange Membrane (PEM) Water Electrolyzer Application

The stainless steel (SS) is an appropriate material for bipolar plate of PEM water electrolyzer owing to its high electron transport, superior mechanical characteristics, and formability, but it needs a coating to increase corrosion resistance. Herein, the multilayer coating of Au/Cr/Au on the SS was developed by electroplating method and corrosion studied were performed for bipolar plate application of PEM water electrolyzer. The gold striking underlayer on the SS substrate passivated the surface oxides and facilitated a dense electroplated chromium layer. Furthermore, a uniform gold protective layer was electroplated on the chromium coated substrate to achieve a promising anti-corrosive property. The Au/Cr/Au 316L SS substrate presented approximately ten times lower corrosion current density, and positive shift of corrosion potential as compared to uncoated SS substrate. The Au/Cr/Au/ 316 L SS was analysed for long time, and it depicted slower corrosion as compared to without striking underlayer of gold (Au/Cr/ 316L SS).