Current-Time Behavior of Smooth and Porous PtRu Surfaces for Methanol Oxidation
- 1 January 2001
- journal article
- Published by The Electrochemical Society in Journal of the Electrochemical Society
- Vol. 148 (5), A496-A501
- https://doi.org/10.1149/1.1365142
Abstract
Smooth ultrahigh vacuum-cleaned PtRu alloys used as model catalysts for methanol oxidation, present a continuous loss of activity under potentiostatic conditions. After a potential step, e.g., from 50 to 500 mV vs. reference hydrogen electrode, chronoamperometric curves first show a steep decrease over 5-10 min followed by a slower decrease over several hours. The latter decay exhibits a time−1 behavior for different catalyst compositions, with higher slopes for the catalysts with less activity. The first current decay can be repeatedly observed by restarting the experiment after setting the potential back to the initial value, thus indicating a certain degree of reversibility. The slow decrease in activity, however, cannot be recovered by this means. But stepping the potential to higher anodic values, e.g., up to 1.2 V, the original surface activity can be obtained again. Optimized porous PtRu surfaces, on the other hand, do not show any comparable decrease after a respective potential step. The possible origin of the different behavior of smooth and porous surfaces is discussed. © 2001 The Electrochemical Society. All rights reserved.Keywords
This publication has 36 references indexed in Scilit:
- A theoretical study of CO adsorption on Pt, Ru and Pt–M (M=Ru, Sn, Ge) clustersSurface Science, 2000
- Status of the development of a direct methanol fuel cellJournal of Power Sources, 1999
- Methanol Oxidation on PtRu Electrodes. Influence of Surface Structure and Pt−Ru Atom DistributionLangmuir, 1999
- High-Pressure Oxidation of Ruthenium as Probed by Surface-Enhanced Raman and X-Ray Photoelectron SpectroscopiesJournal of Catalysis, 1997
- Cleavage of the C−C Bond during the Electrooxidation of 1-Propanol and 2-Propanol: Effect of the Pt Morphology and of Codeposited RuLangmuir, 1997
- Ultrathin Films of Ruthenium on Low Index Platinum Single Crystal Surfaces: An Electrochemical StudyLangmuir, 1997
- Electrocatalysis of Organic Oxidations: Influence of Water Adsorption on the Rate of ReactionThe Journal of Physical Chemistry B, 1997
- Temperature‐Dependent Methanol Electro‐Oxidation on Well‐Characterized Pt‐Ru AlloysJournal of the Electrochemical Society, 1994
- Advances in direct oxidation methanol fuel cellsJournal of Power Sources, 1994
- A Self‐Contained Miniature Hydrogen Reference ElectrodeJournal of the Electrochemical Society, 1986