Effect of Oxygen Gas on Corrosion Behavior of Electro-Polymerization PANI Coating in PEMFC Environments

PANI coating was electrochemically synthesized by cyclic voltammetry (CV) method on the surface of 316L stainless steel plate. The surface morphology of PANI coating was observed by scanning electron microscopy. The effect of oxygen gas on corrosion behavior of PANI coating in PEMFC environment was investigated. The corrosion performance of the coating was evaluated by potential-time curve and polarization curve as well as electrochemical impedance spectroscopy in a bath containing 1M H2SO4and 2ppM NaF, and the air with a flow rate of 10 ml/min was piped into the testing corrosion cell to simulate the positive cathode condition of PEMFC at 70°C. The potential-time curves illustrated that oxygen gas resulted in the potential decline towards negative direction. Polarization curves showed that corrosion potential of the sample with O2was lower than that of the sample without O2, and the corrosion current density was higher than that of the sample without O2. EIS results indicated that the Nyquist plots were constitute of a capacitive impedance arc and a incline line, and the oxygen gas reduced the anti-corrosion performance of the PANI coating.