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One-dimensional PtO2 at Pt steps: formation and reaction with CO
1Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark.
Physical Review Letters
|December 31, 2005
Summary
A novel one-dimensional (1D) oxide structure forms at platinum (Pt) surface steps, acting as a precursor to Pt oxidation. This 1D oxide reacts more readily with carbon monoxide (CO) than terrace oxygen.
Area of Science:
- Surface Science
- Materials Science
- Catalysis
Background:
- Platinum surfaces are crucial in catalysis.
- Understanding surface oxidation is key to controlling reactivity.
- Step edges often exhibit unique chemical properties.
Purpose of the Study:
- To identify the initial oxidation structure on Pt(332) surfaces.
- To investigate the stability and reactivity of this oxide structure.
- To compare the reactivity of step-oxide vs. terrace-oxide species.
Main Methods:
- Core-level spectroscopy (e.g., XPS, AES) for chemical state analysis.
- Density Functional Theory (DFT) for electronic structure and energetics.
- Controlled exposure to oxygen and subsequent reaction with CO.
Main Results:
- A stable one-dimensional (1D) oxide structure forms at Pt(332) step edges.
- This 1D oxide is more stable than bulk platinum oxides under certain conditions.
- The 1D oxide acts as an oxidation precursor.
- Oxidic oxygen at steps reacts more readily with CO than chemisorbed oxygen on terraces.
Conclusions:
- The 1D oxide at step edges is a crucial intermediate in platinum oxidation.
- Step site reactivity differs significantly from terrace site reactivity.
- This finding has implications for controlling catalytic reactions on platinum.