An Experimental Investigation of the Effect of Platinum on the Corrosion of Cathode Carbon Support in a PEMFC

The possible role of platinum in the carbon corrosion at cell voltage higher than 1.0 V is controversial yet. To gain more insights into this issue, a square-wave potential cycles between 1.0 to 1.5 V was applied to fuel cells comprising cathodes with and without Pt. Using online non-dispersive infrared spectroscopy, we showed that Pt catalyzed the gasification of carbon in the early stage, while upon prolonged exposure to potential cycling (>= 3 h), platinum started to hinder the CO2 production. Based on cyclic voltammetry tests and Raman spectroscopy, the inhibiting effect of platinum on the corrosion was suggested to originate from modifications on carbon surface, where the formation of electroactive sites was limited. Electrode and non-electrode ohmic resistances were distinguished further through electrochemical impedance spectroscopy measurement and the changes in electrode microstructure and surface composition were examined by scanning electron microscope image and energy dispersion X-Ray spectroscopy. The results indicated that Pt reduced the damage of electrode structures after potential cycles.