Molecular Oxygen Adsorption Behaviors on the Rutile TiO2(110)-1脳1 Surface: An in Situ Study with Low-Temperature Scanning Tunneling Microscopy

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• 作者：Shijing Tan ; Yongfei Ji ; Yan Zhao ; Aidi Zhao ; Bing Wang ; Jinlong Yang ; J.G. Hou
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：February 16, 2011
• 年：2011
• 卷：133
• 期：6
• 页码：2002-2009
• 全文大小：1076K
• 年卷期：v.133,no.6(February 16, 2011)
• ISSN：1520-5126

文摘

A knowledge of adsorption behaviors of oxygen on the model system of the reduced rutile TiO₂(110)-1脳1 surface is of great importance for an atomistic understanding of many chemical processes. We present a scanning tunneling microcopy (STM) study on the adsorption of molecular oxygen either at the bridge-bonded oxygen vacancies (BBO_V) or at the hydroxyls (OH) on the TiO₂(110)-1脳1 surface. Using an in situ O₂ dosing method, we are able to directly verify the exact adsorption sites and the dynamic behaviors of molecular O₂. Our experiments provide direct evidence that an O₂ molecule can intrinsically adsorb at both the BBO_V and the OH sites. It has been identified that, at a low coverage of O₂, the singly adsorbed molecular O₂ at BBO_V can be dissociated through an intermediate state as driven by the STM tip. However, singly adsorbed molecular O₂ at OH can survive from such a tip-induced effect, which implies that the singly adsorbed O₂ at OH is more stable than that at BBO_V. It is interesting to observe that when the BBO_Vs are fully filled with excess O₂ dosing, the adsorbed O₂ molecules at BBO_V tend to be nondissociative even under a higher bias voltage of 2.2 V. Such a nondissociative behavior is most likely attributed to the presence of two or more O₂ molecules simultaneously adsorbed at a BBO_V with a more stable configuration than singly adsorbed molecular O₂ at a BBO_V.