Oxidation and thermal stability of nickel deposited on a thin alumina support

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• 作者：Alexander Winkler ; Holger Borchert and Katharina Al-Shamery
• 关键词：X-ray photoelectron spectroscopy ; Low energy electron diffraction ; Physical vapour deposition ; Nickel ; Nickel oxides ; Aluminum oxide
• 刊名：Surface Science
• 出版年：2006
• 出版时间：1 August 2006
• 年：2006
• 卷：600
• 期：15
• 页码：3036-3044
• 全文大小：693 K

文摘

The activity of supported Ni catalysts can easily be affected by high temperatures and oxidative atmosphere. In order to study the origin of this behaviour, we performed systematic LEED and XPS investigations on a model system prepared by physical vapour deposition of Ni on a thin epitaxial alumina film on NiAl(1 1 0). Annealing experiments showed that deposited Ni is thermally stable up to 370 K. Further annealing seems to lead first to changes in the island structure and then, at temperatures above 480 K, to diffusion of Ni through the alumina film. Analysis of the complex oxidation behaviour revealed that there is a competition between oxidation of the Ni deposit and of the NiAl support. The latter process is probably enabled by a solid state reaction at the interface which means that Ni catalyses the further oxidation of the support. While the surface of the deposited Ni clusters is easily oxidised, the further oxidation processes of the Ni particles and the support were found to be diffusion-controlled.