Structurally Accurate Model for the “29”-Structure of Cu x O/Cu(111): A DFT and STM Study
Structurally Accurate Model for the “29”-Structure of Cu x O/Cu(111): A DFT and STM Study
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Cu x O/Cu(111) 的 29 结构的结构精确模型：DFT 和 STM 研究
DOI：
10.1021/acs.jpcc.6b01284
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Sykes, E. Charles
中科院分区：
文献类型：
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作者：
Therrien, Andrew J.;Zhang, Renqin;Lucci, Felicia R.;Marcinkowski, Matthew D.;Hensley, Alyssa;McEwen, Jean-Sabin;Sykes, E. Charles
铜是许多重要化学反应的常用催化剂，包括低温水煤气变换、NOx的选择性催化还原、甲醇合成、甲醇蒸汽重整和甲醇的部分氧化。在这些反应过程中，表面氧化的程度或活性部位的氧化态一直存在争议，并且已知对反应速率有很大的影响。因此，阐明铜表面氧化物的原子尺度结构是对多相催化反应机理更全面理解的重要一步。所谓的“29”单层氧化膜是Cu（111）氧化过程中常见的中间产物。它的晶胞的大尺寸迄今为止阻止了其结构的确定模型的发展。利用高分辨扫描隧道显微镜（STM）和密度泛函理论（DFT）计算，我们得到了Cu（111）衬底上“29”CuxO薄膜的模型。实验和计算STM图像之间有很好的协议在一系列的偏见。通过第一性原理相图的构建，我们进一步发现，由DFT计算得到的“29”结构确实是在所考虑的实验条件下最稳定的结构。这项工作产生的“29”氧化膜的原子尺度结构的准确图片，因此开始了解吸附位点和反应机制的基础上，这个催化相关的表面。
Copper is a common catalyst for many important chemical reactions including low-temperature water gas shift, selective catalytic reduction of NOx, 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” CuxO 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.