Differently with alloy catalysts, Pd has been used to promote the oxygen reduction reaction (ORR) activity of the cathode catalyst in fuel cells by decorating the surface of Pt supported on carbon black with Pd. Both the Pt-Pd/C catalyst with different ratios of Pt to Pd and the Pt/C catalyst of reference were fabricated by polyol processes in ethylene glycol solution. The results of XRD and TEM show that the average size of Pt-Pd noble metal particles is 1.75～2.50 nm which are highly dispersed on the carbon supports. The hydrogen desorption property and electrocatalytic activity of the Pt-Pd/C catalyst with different ratios of Pt to Pd and the Pt/C catalyst were investigated by cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements. The CV test shows that the Pd-modified Pt/C catalysts have lower electrochemical surface area (ECSA) than Pt/C catalyst. However, compared with the conventional Pt/C catalyst, the Pd-modified Pt/C catalyst presents a high ORR activity in RDE measurements, although both of them have a similar behavior of kinetics of oxygen reduction based on their Tafel slope characteristics.

Key words: modification, oxygen reduction reaction, catalyst, proton exchange membrane fuel cell