X-RAY-ABSORPTION NEAR-EDGE STRUCTURE STUDY OF THE ELECTROOXIDATION REACTION OF CO ON PT50RU50 NANOPARTICLES

X-ray absorption near edge structure (XANES) spectra at the Ru K absor ption edge were recorded on Pt50Ru50 nanoparticles during the electro- oxidation of CO. They are compared with the spectra obtained at the sa me electrochemical potential under inert gas. In the latter case, the XANES spectra change drastically in shape whereas in the former case t hey do not. The change in shape is related to a change in oxidation st ate of ruthenium atoms. This result clearly shows that the rate-determ ining step rds for CO oxidation is the oxidation of ruthenium atoms on nanometric Pt50Ru50 particles.