Interfacial and Surface Structures of CeO2-TiO2 Mixed Oxides

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• 作者：Jun Fang ; Huizhi Bao ; Bo He ; Fang Wang ; Dejun Si ; Zhiquan Jiang ; Zhiyun Pan ; Shiqiang Wei ; Weixin Huang
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：December 27, 2007
• 年：2007
• 卷：111
• 期：51
• 页码：19078 - 19085
• 全文大小：587K
• 年卷期：v.111,no.51(December 27, 2007)
• ISSN：1932-7455

文摘

The interfacial and surface structures of CeO₂-TiO₂ mixed oxides prepared by the sol-gel method havebeen investigated in detail by means of X-ray diffraction (XRD), BET surface area measurement, X-rayabsorption spectroscopy (XAS), high-resolution transmission electron microscope (HRTEM), and selectivechemisorption of methyl orange. TiO₂ and CeO₂ are in the anatase phase and the cubic fluorite phase inCeO₂-TiO₂ mixed oxides, respectively. The mixed oxides exhibit much higher surface areas than the individualoxides and are with both mesopores and micropores. XAS results suggest that Ce atoms nucleate as cubic[CeO₈] polyhedrons with the formation of a Ce-O-Ti interface in mixed oxides. With the increasing Ce/TiO₂ weight ratio, the cubic fluorite CeO₂ crystallites gradually develop. TiO₂ anatase forms ultrafine particlesin mixed oxides, whose local structure is stabilized by the presence of CeO₂. HRTEM results reveal that theexposed surfaces of mixed oxides depend on the Ce concentration. Chemisorption results of methyl orangethat was found to adsorb profoundly on CeO₂ but little on TiO₂ demonstrate that CeO₂ in mixed oxidesexhibits much lower adsorption capacity toward methyl orange than pure CeO₂. Our results demonstrate anapproach to characterize interfacial and surface structures of complex mixed oxides, which are of greatimportance in understanding their properties.