Analysis of the Ionomer Coverage of Pt Surface in PEMFC

We have developed a new cyclic voltammetry (CV) technique to analyze the ionomer coverage of Pt/C surfaces. The ionomer coverage ratio was estimated by comparing the capacitance current under perfluorohydrocarbon solvent and under nitrogen. When the cathode electrode was immersed in perfluorohydrocarbon solvent, the proton supply from adsorbed water is inhibited by blocking water adsorption. Accordingly, proton supplies from the ionomer can be differentiated from that of adsorbed water. Using this technique, the effect of carbon species on the ionomer coverage ratio was investigated. Using Ketjen carbon in the catalyst layer resulted a low ionomer coverage ratio, which also influenced V-I performance.