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CO adsorption on pure and binary-alloy gold clusters: a quantum chemical study
Ajay M Joshi1, Mark H Tucker, W Nicholas Delgass
1School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, USA. amjoshi@ecn.purdue.edu
The Journal of Chemical Physics
|November 30, 2006
Summary
Density-functional theory analysis reveals CO adsorption trends on binary gold alloy clusters. Alloying with gold generally enhances CO adsorption, with specific trends observed for different metal combinations and cluster sizes.
Area of Science:
- Computational chemistry
- Surface science
- Materials science
Background:
- Understanding CO adsorption on metal clusters is crucial for catalysis and materials design.
- Binary gold alloys offer tunable electronic and chemical properties for surface interactions.
- Previous studies have explored CO adsorption on pure metals, but alloy behavior requires detailed investigation.
Purpose of the Study:
- To investigate nondissociative CO adsorption on various binary gold alloy clusters (Au(n)M(m)).
- To determine the influence of alloying elements (Cu, Ag, Pd, Pt) on CO adsorption energy and binding modes.
- To establish structure-activity relationships for CO adsorption on these alloy systems.
Main Methods:
- Density-functional theory (DFT) calculations were employed to model CO adsorption.
- Basis-set superposition error corrections were applied to adsorption energy calculations.
- Both internal energy of adsorption (DeltaU(ads)) and Gibbs free energy of adsorption (DeltaG(ads)) were computed at standard conditions.
Main Results:
- CO predominantly binds in a onefold (atop) configuration, except for specific Pd and Pt clusters.
- Adsorption affinity follows the trend: Pd > Pt > Au > Cu > Ag.
- Alloying Ag/Cu with Au enhances CO adsorption, while Pd-Pt alloying with Au decreases it; specific trends were observed for dimers and trimers.
Conclusions:
- The study provides a comprehensive understanding of CO adsorption on binary gold alloy clusters.
- Alloying effects on CO adsorption are highly dependent on the specific metal combination and cluster size.
- A linear correlation between CO binding energy and CO bond elongation was observed, with mechanistic insights into donation and back-donation.
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