Atomic-Scale Study of Ambient-Pressure Redox-Induced Changes for an Oxide-Supported Submonolayer Catalyst: VOx/伪-TiO2(110)
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- 作者：Zhenxing Feng ; Lei Cheng ; Chang-Yong Kim ; Jeffrey W. Elam ; Zhan Zhang ; Larry A. Curtiss ; Peter Zapol ; Michael J. Bedzyk
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2012
- 出版时间：October 4, 2012
- 年：2012
- 卷：3
- 期：19
- 页码：2845-2850
- 全文大小：328K
- 年卷期：v.3,no.19(October 4, 2012)
- ISSN：1948-7185
文摘
The activity of supported catalysts is strongly linked to the structure of the surface species. However, direct in situ structural measurements of submonolayer catalysts are lacking. Using in situ X-ray standing wave analysis combined with ex situ X-ray photoelectron spectroscopy and atomic force microscopy, we observed reversible redox-induced surface cation dynamics for three-fourths of a monolayer of vanadia grown by atomic-layer deposition on an 伪-TiO2(110) surface. On the basis of first-principles density functional theory calculations, we propose vanadia submonolayer structures that agree with and suggest explanations for the observed redox-induced structural changes. Under oxidation conditions, the correlated submonolayer structure is a 2D trimer-decorated polymeric chain along the rutile [鈭? 1 0] direction; under reducing conditions, the more stable polymeric chain remains unreduced, whereas the less stable decorating trimers become reduced and uncorrelated with the support lattice. These results show that a large fraction of V sites retains redox activity at submonolayer V coverages.