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Electrochemical characterisation of gold on Pt{h k l} for ethanol electrocatalysis

Hazzazi, Omar A., Attard, Gary Anthony, Wells, Peter Bernard, Vidal-Iglesias, F. J. and Casadesus, Meritxell 2009. Electrochemical characterisation of gold on Pt{h k l} for ethanol electrocatalysis. Journal of Electroanalytical Chemistry 625 (2) , pp. 123-130. 10.1016/j.jelechem.2008.10.016

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The cyclic voltammetric (CV) behaviour of gold adsorbed on Pt{h k l} electrodes is reported. It is found that stepped surfaces vicinal to Pt{1 1 1} exhibit preferential adsorption of gold at step sites. However, for stepped surfaces containing Pt{1 0 0} terraces, adsorption of gold at step and terrace site occurs with equal probability, although for Pt{n 1 1} electrodes with n < 7 (i.e. electrodes containing short Pt{1 0 0} terraces), slight preference for step site adsorption is still observed. This behaviour is similar to that reported previously for Bi adsorption on Pt{h k l} and is interpreted in terms of slower rates of gold atom surface diffusion across Pt{1 0 0} vs. Pt{1 1 1} terraces. By comparing the electrochemical response of gold adlayers on Pt{h k l} with previously published bulk Au{h k l} voltammetry, it is deduced that the gold overlayers on Pt{h k l} are pseudomorphic in nature. This finding is in agreement with previous UHV and electrochemical results for gold deposition on platinum. Using such gold modified Pt{h k l} electrodes as model surfaces, we also report, for the first time, the electrooxidation of ethanol on Au/Pt{h k l} in alkaline aqueous solution. The ethanol oxidation reaction (EOR) is shown to be structure sensitive for submonolayer gold coverages. In fact, a maximum in the rate of EOR at platinum sites adjacent to gold islands is observed between approximately 0.4–0.6 monolayers of gold on Pt{1 0 0}, Pt{1 1 1} and Pt{1 1 0} in 0.1 M NaOH(aq). A second electrooxidation state at more positive potentials for 0 < θAu < 1 ascribed to EOR at pure gold sites is also observed, at least for Pt{1 1 1} and Pt{1 0 0}. On Pt{1 1 1}, the potential range and activity of EOR in this second process is similar to bulk gold whereas for submonolayer gold films on Pt{1 0 0}, the peak is shifted to more negative potentials.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Cardiff Catalysis Institute (CCI)
Subjects: Q Science > QD Chemistry
Uncontrolled Keywords: Cyclic voltammetry; Gold adsorption; Pt{h k l}; Ethanol electrooxidation
Publisher: Elsevier
ISSN: 1572-6657
Last Modified: 05 Jun 2017 02:09

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