An X-ray photoelectron spectroscopic study on the effect of Ru and Sn additions to platinised carbons

Electro-catalytic oxidation of methanol is known to be promoted on Pt–Ru and Pt–Sn surfaces. Whilst Ru addition to Pt has been unambiguously acknowledged to enhance the methanol-oxidation reaction, the effect of Sn in the Pt–Sn alloy remains shrouded with inconsistencies. In order to further elucidate this problem, an X-ray photoelectron spectroscopic study is carried out on various carbon-supported Pt–Ru and Pt–Sn catalysts. It is argued that while Sn produces a modification in electronic environment around Pt-sites through a charge transfer in the Pt–Sn alloy, Ru-sites in the Pt–Ru system promote the formation of labile-bonded oxygenated species in the vicinity of methanolic residues adsorbed on Pt-sites facilitating them to oxidise as carbon-di-oxide. q1999 Published by Elsevier Science B.V. All rights reserved