The effect of the cooling atmosphere in the preparation of flame-annealed Pt(111) electrodes on CO adlayer oxidation |
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Affiliation: | 1. European Synchrotron Radiation Facility, 71 Avenue des Martyrs, Grenoble 38000, France;2. Chemistry Department, University of Victoria, PO Box 1700, Victoria, BC V8W 2Y2, Canada;3. Institute of Experimental and Applied Physics, Kiel University, Olshausenstr. 40, Kiel 24098, Germany |
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Abstract: | The effect of the cooling atmosphere on the rate of CO adlayer oxidation on flame-annealed Pt(111) has been studied. Cooling of a flame-annealed Pt(111) electrode in air results in a higher amount of crystalline defects compared to Pt(111) cooled in a hydrogen–argon stream. Although the blank profiles in 0.5 M H2SO4 of Pt(111), cooled in air and under oxygen exclusion, are virtually identical, CO adlayer oxidation occurs at significantly lower overpotentials on the former electrode. Three voltammetric peaks are observed for subsaturated CO adlayer oxidation on Pt(111), cooled in Ar+H2 mixture, while only two peaks develop in the case of a Pt(111) surface cooled in air. Random crystalline defects, introduced via cooling of a flame-annealed Pt(111) in air, enhance CO adlayer oxidation, and apparently also suppress the third high-potential peak observed on a quasi-perfect (111) surface. The high sensitivity of the saturated CO adlayer oxidation to the presence of crystalline defects on Pt(111) can hence be used as a straightforward, sensitive, though qualitative method to assess the degree of crystalline order of the electrode. |
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