Atomic scale insights on the electronic and geometric effects in the electro-oxidation of CO on PtxRu1-x/Ru(0001) surface alloys
| Autor: | Jens Klein, Rolf Jürgen Behm, Albert K. Engstfeld, Sylvain Brimaud |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Materials science
General Chemical Engineering 02 engineering and technology Substrate (electronics) 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Atomic units 0104 chemical sciences law.invention chemistry.chemical_compound chemistry law Electrode Monolayer Electrochemistry Physical chemistry Reactivity (chemistry) Scanning tunneling microscope 0210 nano-technology Bifunctional Bimetallic strip |
| Zdroj: | Electrochimica Acta. 306:516-528 |
| ISSN: | 0013-4686 |
| Popis: | The enhanced activity of various bimetallic catalysts/electrodes in electrocatalytic reactions is usually ascribed to a bifunctional mechanism. This seems to neglect other effects arising from electronic modifications and further geometric effects, which are known to strongly affect the interaction of these surfaces with adsorbed species. In this work we elucidate the role of electronic and geometric effects on the activity of structurally well-defined PtRu electrodes in the bulk CO oxidation reaction, using model electrodes prepared and structurally characterized on an atomic scale by scanning tunneling microscopy under ultrahigh vacuum (UHV) conditions. Samples include PtxRu1-x/Ru(0001) surface alloys with varying Pt content consisting of a Ru(0001) substrate and a PtxRu1-x alloy surface layer as well as a Ru(0001) electrode covered by a pseudomorphic Pt monolayer (x = 1), and Pt(111) for comparison. Comparing the structural/chemical properties and the relative abundance of specific PtnRum ensembles on the electrode surfaces with the respective bulk CO electro-oxidation activity enabled us to identify Pt1Ru3 ensembles as the most active ensembles under the present conditions. The importance of electronic and geometric ensemble effects are discussed. The results demonstrate that the reactivity of bimetallic surfaces is much more complex than described by the classical bifunctional mechanism, which is proposed as a general feature. |
| Databáze: | OpenAIRE |
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