Particle-Size Effect of Pt Anode Catalysts on H2O2 Production Rate and H2 Oxidation Activity at 20 to 80 °C

Abstract

Polymer electrolyte membranes (PEMs) for fuel cells are chemically degraded by ·OH radicals, generated from H2O2, which is produced by a reaction of hydrogen adsorbed on the Pt anode with O2 diffusing through the PEM. In order to obtain a clue for designing the anode catalyst with low production rate of H2O2 and high activity for the hydrogen oxidation reaction (HOR), we have examined the H2O2 production rate at Pt catalysts as a function of particle size d Pt ranging from 2 nm to 20 nm over a practical temperature range between 20 and 80 °C in 0.1 M HClO4. The H2O2 production rate [per geometric area with 1.5 to 2-layer height of catalyst layer] was found to decrease with increasing d Pt, accompanied by a penalty of decreased mass activity for the HOR. The use of Pt skin-covered PtCo/C is shown to be an attractive potential solution, providing a breakthrough in simultaneously achieving low H2O2 production and high HOR activity.