Molybdenum addition enhancing the corrosion behaviors of 316 L stainless steel in the simulated cathodic environment of proton exchange membrane fuel cell

• 316 L stainless steel is in the passive state in H2SO4 solution.
• The passivity is enhanced with increase in Mo.
• The passive film on 316 L SS is modeled as a p-n heterojunction.
• The donor and acceptor densities decrease with increasing Mo.

The influence of Mo on the corrosion behaviors of 316 L SS in the simulated cathodic environment of proton exchange membrane fuel cell (PEMFC), was investigated by potentiodynamic polarization curve, electrochemical impedance spectroscopy (EIS), Mott- Schottky plot and X-ray photoelectron spectroscopy (XPS). The results showed that 316 L SS was in the passive state in the simulated cathodic environment of PEMFC, the passive current density decreased and the passive potential region enlarged with increasing Mo. The compactness and resistance of the passive film on 316 L SS enhanced with increasing Mo, implying the improved film protection. Mott-Schottky plots revealed that Mo can decrease the donor and acceptor densities of the inner and outer films. XPS results showed that Mo can increase the thickness of the passive film, and can increase the Cr2O3 content in the passive film.