Platinum-Iridium Alloys as Oxygen Reduction Electrocatalysts for Polymer Electrolyte Fuel Cells

Abstract

Platinum-iridium (Pt-Ir) alloy electrocatalysts for polymer electrolyte fuel cell (PEFC) cathodes were prepared, and their physical and electrochemical properties were examined. A variety of unsupported Pt-Ir alloy catalysts was prepared in hot KOH solution, and the obtained Pt-Ir alloy catalysts were aggregates of fine particles <100nmHClO4HClO4 solution and determination of the specific activity during PEFC single-cell operations. The ORR kinetic analysis by the RDE showed that alloying Pt with Ir, especially with 5-20 wt % Ir, enhanced the catalytic activity for the ORR by a factor of more than 1.5 at 0.8 V vs RHE. The relationship between the specific current density and Ir content under PEFC operating conditions also showed enhanced ORR activity at 5-20 wt % Ir, which was consistent with the RDE results.