Molybdenum modified AISI 304 stainless steel bipolar plate for proton exchange membrane fuel cell

A molybdenum diffusion layer has been prepared on the surface of AISI 304 stainless steel (Mo-304 SS) by means of plasma surface diffusion alloying method. X-ray diffraction data show that the molybdenum modified layer of 304 SS mainly consists of cubic Mo. The results of scanning electron microscopy in combination with energy-dispersive X-ray analysis spectrometer indicate that the as-prepared molybdenum diffusion layer is ∼3 μm with dominant molybdenum element. A series of electrochemical evaluation tests were conducted on the Mo-304 SS specimens to determine if the Mo-304 SS is suitable to be used as proton exchange membrane fuel cell (PEMFC) bipolar plate. The corrosion resistance and the passivated behavior of the Mo-304 SS are improved, which yield better results than those found in the untreated 304 SS after the potentiodynamic and potentiostatic polarization under simulated typical PEMFC operating conditions (0.05 M H₂SO₄ +2 ppm F⁻ solution at 70 °C purged with either hydrogen or air). Also, the interfacial contact resistance for the as-prepared Mo-304 SS is ameliorated. The molybdenum modified 304 SS can be a promising candidate bipolar plate for proton exchange membrane fuel cell.