STM investigation of the coadsorption and reaction of oxygen and hydrogen on Ni(110)
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- 作者：Sprunger ; P.T. ; Besenbacher ; F. ; Stensgaard ; I. ; Okawa ; Y. ; Tanaka ; K.
- 关键词：Catalysis ; Chemisorption ; Hydrogen ; Low index single crystal surfaces ; Nickel ; Oxygen ; Scanning tunneling microscopy ; Surface chemical reaction
- 刊名：Surface Science
- 出版年：1995
- 出版时间：December 20, 1995
- 年：1995
- 卷：344
- 期：1-2
- 页码：98-110
- 全文大小：1.27 M
文摘
The interaction and reaction between oxygen and hydrogen on Ni(110) has been studied by STM. For O and H surface coverages below 1/2 ML, coadsorption experiments at 300 K indicate that there is a large local repulsion between the differing species, which consequently phase separate into (2 × 1)-O and (1 × 2)-H structural domains. However, if the O surface concentration is at or above 1/2 ML, adsorption of H is inhibited due to a site blocking mechanism. It is revealed that the titration reaction of a pre-oxygenated Ni(110) surface (θO≤2/3 ML) at 473 K initiates preferentially at step edges running along the [110] direction and subsequently progresses across flat terraces. Details concerning the overall titration rate, as a function of the initial oxygen coverage, are shown to be dominated by this local reaction mechanism. The interaction of hydrogen with the higher density (9 × 5)-O phase (θO 
1 ML) is markedly different from that of the lower density phases; relatively small amounts of hydrogen induce a structural phase transformation in which the metastable (9 × 5)-O is converted to domains of(3 × 1)t-O and NiO(100) phases.
1 ML) is markedly different from that of the lower density phases; relatively small amounts of hydrogen induce a structural phase transformation in which the metastable (9 × 5)-O is converted to domains of(3 × 1)t-O and NiO(100) phases.