Surface Structures and Electrochemical Activities of PtRu Over layers on Ir Nanoparticles

Abstract

PtRu overlayers were deposited on carbon-supported Ir nanoparticles with various Pt:Ru compositions. Structural and electrochemical characterizations were performed using transmission electron microscopy (TEM), X-ray diffraction, high-resolution powder diffraction (HRPD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and CO stripping voltammetry. The PtRu overlayers were selectively deposited on the Ir nanoparticles with good uniformity of distribution. As a result, the PtRu utilization of the present samples was higher than that of PtRu/C. The mass-specific activities for methanol oxidation were also significantly higher. Single-cell performance using the Pt2Ru1 overlayer sample as an anode catalyst was slightly higher than that obtained using commercial PtRu/C despite the fact that the PtRu anode loading for Pt2Ru1/Ir/C was only 42% of that of PtRu/C.