Oxygen Reduction Activity of Pt and Pt-Alloy Catalysts: A Comparison between Kinetic Measurements and Polymer Electrolyte Fuel Cell Experiments

摘要

Applying the (thin-film) RRDE technique, we could demonstrate that the ORR activity of the alloyed electrodes and catalysts is a factor of 2-3 higher compared to the equally prepared Pt-electrode and catalyst. Similar apparent energies of activation and similar peroxide yields give rise for the assumption of identical reaction mechanisms. The assumption of modified oxide adsorp-tion/desorption properties could serve as an explanation for the observed activity enhancement. The slightly inferior behavior of the commercially available PtCo-gde compared to the Pt-gde is not yet completely understood. Different wetting properties, variation in the structure and overall composition of the gas diffusion electrode (proportion of catalyst, binder or other additives) or modified particle surface compositions could serve as an explanation. In any case the PtCo-gde needs to be optimized.