Adsorption-driven surface segregation of the less reactive alloy component.
Klas J Andersson1, Federico Calle-Vallejo, Jan Rossmeisl
1Center for Individual Nanoparticle Functionality (CINF), Department of Physics, NanoDTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Journal of the American Chemical Society
|January 27, 2009
Summary
Carbon monoxide (CO) adsorption unexpectedly drives copper (Cu) to the surface of a copper-platinum (CuPt) alloy. This discovery offers new ways to engineer alloy surfaces for catalysis.
Area of Science:
- Surface science
- Materials science
- Catalysis
Background:
- Adsorbate-induced surface segregation typically involves the more reactive alloy component.
- Previous studies observed segregation of the more reactive element upon adsorbate interaction.
Purpose of the Study:
- To investigate the surface behavior of a CuPt near-surface alloy under CO adsorption at elevated conditions.
- To understand the mechanism behind unexpected surface segregation phenomena.
Main Methods:
- Experimental study of CuPt near-surface alloys.
- Adsorption of carbon monoxide (CO) at high pressures and temperatures.
- Analysis of surface alloy structure and segregation behavior.
Main Results:
- CO adsorption induced segregation of the less reactive component, copper (Cu), to the surface of the CuPt alloy.
- Formation of a stable, self-organized CO/CuPt surface alloy structure was observed.
- The phenomenon is attributed to a strengthened Pt-CO bond in the presence of Cu in the surface layer.
Conclusions:
- The study reveals a counterintuitive mechanism of adsorbate-induced surface segregation.
- The findings are applicable to other coinage/platinum-group bimetallic surface alloys.
- This work enables novel strategies for the dynamic engineering of alloy surfaces in catalysis.
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