Density functional theory calculations for the interaction of oxygen with reduced M/SnO2(1 1 0) (M=Pd, Pt) surfaces
✍ Scribed by Yoichi Yamaguchi; Kenji Tabata; Eiji Suzuki
- Publisher
- Elsevier Science
- Year
- 2003
- Tongue
- English
- Weight
- 345 KB
- Volume
- 526
- Category
- Article
- ISSN
- 0039-6028
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✦ Synopsis
Density functional theory calculations within the generalized gradient approximation have been performed for the interaction of oxygen with reduced M/SnO 2 (1 1 0) (M ¼ Pd, Pt) surfaces. There are larger dissociation barriers of sideon type chemisorbed O 2 molecules assigned as a superoxo (O À
2 ) species for Pd/SnO 2 , an intermediate oxygen species between O À 2 and preoxo (O 2À 2 ) for Pt/SnO 2 than the barrier less dissociation of O 2À 2 for the reduced SnO 2 (1 1 0) surface. An adsorbed O À species produced by the dissociation of these species shows higher migration barriers of %30-40 kcal/ mol over the noble metal, indicating its limited migration on the surfaces. It is also found that the catalytic activity of O À is much weakened at vacant bridging oxygen sites connected to the noble metal. These characters of O À on the surfaces may favor the selective oxidation of methane to C 1 -oxygenates (methanol and formaldehyde) compared to the SnO 2 surface remaining a highly catalytically active O À under the lower migration barriers.