New Insights into the Mechanism and Kinetics of Adsorbed CO Electrooxidation on Platinum: Online Mass Spectrometry and Kinetic Monte Carlo Simulation Studies

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• 作者：Hongsen Wang ; Zenonas Jusys ; R. J眉rgen Behm ; H茅ctor D. Abru帽a
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：May 24, 2012
• 年：2012
• 卷：116
• 期：20
• 页码：11040-11053
• 全文大小：552K
• 年卷期：v.116,no.20(May 24, 2012)
• ISSN：1932-7455

文摘

The electrooxidation of saturated CO adlayers on Pt/Vulcan and polycrystalline Pt has been studied by potential step techniques combined with differential electrochemical mass spectrometry (DEMS) and kinetic Monte Carlo (KMC) simulations. DEMS was used to selectively monitor the CO_ad electrooxidation, via the CO₂ formation rate, without interference from the pseudocapacitive double-layer charging and electrode surface oxidation, while the KMC simulations were employed to understand the mechanism and kinetics of CO_ad electrooxidation at the molecular level. Our DEMS data show that the current transients of CO_ad electrooxidation on polycrystalline Pt and Pt/Vulcan exhibit an initial spike immediately after the potential step, followed by a slow current decay and finally a broad main peak. The temporal evolution of the transients depends strongly on the oxidation potential applied, resulting in the overlap of the initial spike and the main peak for high potentials. A model is proposed to account for the observed phenomena. On the basis of this model, we developed a kinetic Monte Carlo simulation code specific to the electrooxidation of adsorbed CO on Pt. The simulations reproduce the experimental data very well, confirming the robustness of our model.