Atomic-Scale Study of Ambient-Pressure Redox-Induced Changes for an Oxide-Supported Submonolayer Catalyst: VOx/alpha-TiO2(110)

作者：Feng Zhenxing; Cheng Lei; Kim Chang Yong; Elam Jeffrey W; Zhang Zhan; Curtiss Larry A; Zapol Peter; Bedzyk Michael J^*

来源：Journal of Physical Chemistry Letters, 2012, 3(19): 2845-2850.

DOI：10.1021/jz3011546

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 alpha-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 [-1 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.

• 出版日期2012-10-4
• 单位西北大学