Structurally Accurate Model for the “29”-Structure of CuxO/Cu(111): A DFT and STM Study

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• 作者：Andrew J. Therrien ; Renqin Zhang ; Felicia R. Lucci ; Matthew D. Marcinkowski ; Alyssa Hensley ; Jean-Sabin McEwen ; E. Charles H. Sykes
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 26, 2016
• 年：2016
• 卷：120
• 期：20
• 页码：10879-10886
• 全文大小：552K
• 年卷期：0
• ISSN：1932-7455

文摘

Copper is a common catalyst for many important chemical reactions including low-temperature water gas shift, selective catalytic reduction of NO_x, methanol synthesis, methanol steam reforming, and partial oxidation of methanol. The degree of surface oxidation, or the oxidation state of the active site, during these reactions has been debated and is known to have a large influence on the reaction rates. Therefore, elucidating the atomic-scale structure of copper surface oxides is an important step toward a fuller understanding of reaction mechanisms in heterogeneous catalysis. The so-called “29” monolayer oxide film is a common intermediate in the oxidation of Cu(111). The large size of its unit cell has thus far prevented the development of a definitive model for its structure. Using high-resolution scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, we arrive at a model for the “29” Cu_xO film on Cu(111). There is very good agreement between experimental and computational STM images over a range of biases. Through the construction of a phase diagram from first-principles, we further find that the “29” structure derived from the DFT calculations is indeed the most stable structure under the experimental conditions considered. This work yields an accurate picture of the atomic scale structure of the “29” oxide film and therefore a basis for beginning to understand adsorption sites and reaction mechanisms on this catalytically relevant surface.