Surface Treatment of Pt Cathode Using Ceria Infiltration for High Performance Polymer Electrolyte Membrane Fuel Cells

This study evaluates the performance and stability of Pt cathodes, which are treated by infiltrating cerium oxide (CeOx) onto their surfaces, in polymer electrolyte membrane fuel cells. The concentration of CeOx on the surface of Pt is adjusted by varying the concentration of the cerium precursor in the infiltration solution. The peak power density of the cell using the Pt cathode featuring the optimal amount of infiltrated CeOx is as high as 400 mW cm−2 at 70 °C, which is approximately 40% higher than that of the cell using the untreated Pt cathode under identical test conditions. Electrochemical impedance analysis confirms that this increase in peak power density is clearly attributed to the decrease in cathodic polarization impedance, which implies that the CeOx deposited on the surface of Pt enhances the catalytic performance of Pt. The infiltration of CeOx on the surface of Pt is also confirmed to be truly effective for improving the stability of Pt. Accelerated degradation tests demonstrate that the degradation rates of the cells using CeOx-Pt cathodes are significantly lower than that of the cell using the untreated Pt cathode because of the preservation of electrochemically active sites, as revealed by cyclic voltammetry.