Temperature-Dependent Methanol Electro-Oxidation on Well-Characterized Pt-Ru Alloys

Temperature-Dependent Methanol Electro-Oxidation on Well-Characterized Pt-Ru Alloys

TitleTemperature-Dependent Methanol Electro-Oxidation on Well-Characterized Pt-Ru Alloys
Publication TypeJournal Article
Year of Publication1994
AuthorsHubert A Gasteiger, Nenad Marković, Philip N Ross, Elton J Cairns
JournalJournal of The Electrochemical Society
Volume141
Issue7
Pagination1795-1803
ISSN00134651
Keywordscatalysis catalysts, chemisorption, oxidation electrochemistry, reaction kinetics, surface chemistry, surface composition
Abstract

The kinetics of methanol electro‐oxidation on well‐characterized Pt‐Ru alloy surfaces were measured in sulfuric acid solution as a function of temperature. The alloy surfaces were prepared in ultrahigh vacuum with the surface composition determined by low energy ion scattering. It was found that the activity of Ru towards the dissociative adsorption of methanol is a strong function of temperature. This change in the adsorptive nature of the Ru sites with temperature produced a variation in the optimum surface composition with temperature. The optimum surface had an Ru content which increased with increasing temperature, from close to ≈10 atomic percent (a/o) Ru at 25°C to a value in the vicinity of ≈30 a/o at 60°C. The shift in optimum composition with temperature was attributed to a shift in the rate‐determining step from methanol adsorption/dehydrogenation at low temperature to the surface reaction between the dehydrogenated intermediate and surface oxygen at high temperature. The apparent activation energies were consistent with this change in the rate‐determining step.

DOI10.1149/1.2055007
Short TitleJ. Electrochem. Soc.