Abstract
The microscopic adsorption properties of molecules including SO 2 on ultrafine precious metal particles such as Pd and Pt were investigated using density functional quantum chemical calculations. The precious metal particles which are used as the activation sites in a three-way catalyst (TWC) were modeled by Pd 3 and Pt 3 clusters. The adsorption energies (E ads ) of the molecules on the metal clusters were calculated. Different possible adsorption sites of SO 2 on the Pd 3 and Pt 3 clusters were considered. It was found that the SO 2 adsorption states on the Pd 3 cluster are energetically more stable than those on the Pt 3 cluster when SO 2 molecule was initially located perpendicular to the cluster plane. There were only small differences in the values of E ads for the SO 2 adsorption on each adsorption site of the Pd 3 clusters. However, in the case of the Pt 3 cluster, the values of E ads for SO 2 adsorption depended on the adsorption sites. Moreover, when SO 2 molecule and the cluster were on the same plane, the SO 2 adsorption state on the Pd 3 cluster was energetically less stable than that on the Pt 3 cluster. These results indicate that the adsorption stabilities of SO 2 on the Pd 3 cluster strongly depend on the adsorption geometries. The difference in the adsorption stabilities of SO 2 on the Pd 3 cluster can be explained by the difference in the orbital interaction near the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels.
Original language | English |
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Pages (from-to) | 180-188 |
Number of pages | 9 |
Journal | Applied Surface Science |
Volume | 177 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2001 Jun 8 |
Keywords
- Adsorption energy
- Density functional calculations
- Metal cluster
- Molecular adsorption
- Pd
- Pt
- SO
ASJC Scopus subject areas
- Chemistry(all)
- Condensed Matter Physics
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Surfaces, Coatings and Films