Tungsten deposits facilitate oxidation of the NiAl(110) surface.
Tungsten deposits facilitate oxidation of the NiAl(110) surface.
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DOI：
10.1063/1.5091102
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
T. Meyer;N. Nilius
中科院分区：
文献类型：
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作者：
T. Meyer;N. Nilius
由NiAl(110)氧化形成的氧化铝薄膜作为一种表面科学兼容的模型体系，在晶态和原子平坦的氧化物表面上得到了极大的关注。一个主要的缺点是它的厚度很小，只有0.5 nm，这限制了它在高温和高压下的催化研究中的可能用途。这项工作演示了在NiAl表面预先沉积少量的钨是如何改变氧化特性的。在W颗粒存在下，在850K氧化表面，薄膜厚度增加到2.5 nm，在1050K氧化温度下，膜厚增加到5 nm以上。利用X射线光电子能谱、电子衍射和扫描隧道显微镜对增厚的氧化铝薄膜的厚度、化学计量比和形貌进行了详细的分析。促进氧化物的形成归因于钨独特的氧化还原特性，它稳定了气相中的O2分子，并为进一步的反应产生了活性氧物种。
The alumina film formed by oxidation of NiAl(110) has gained enormous attention as a surface-science compatible model system for a crystalline and atomically flat oxide surface. A main disadvantage is its small thickness of only 0.5 nm that limits possible uses in catalytic studies at elevated temperature and pressure. This work demonstrates how small amounts of tungsten pre-deposited onto the NiAl surface modify the oxidation characteristic. Oxidizing the surface at 850 K in the presence of W particles increases the film thickness to 2.5 nm, a value that rises to more than 5 nm at 1050 K oxidation temperature. Thickness, stoichiometry, and morphology of the thickened alumina films are analyzed in detail by means of X-ray photoelectron spectroscopy, electron-diffraction, and scanning tunneling microscopy. The promoted oxide formation is ascribed to the unique redox properties of tungsten that stabilizes O2 molecules from the gas phase and produces active oxygen species for further reaction.