The effects of alloying and segregation for the reactivity and diffusion of oxygen on Cu3Au(111)
The effects of alloying and segregation for the reactivity and diffusion of oxygen on Cu3Au(111)
复制标题
DOI：
10.1039/c4cp02675f
复制
发表时间：
2014-01-01
影响因子：
3.3
通讯作者：
Kasai, Hideaki
中科院分区：
文献类型：
--
作者：
Oka, Kohei;Tsuda, Yasutaka;Kasai, Hideaki
本文从实验和理论两方面研究了O-2吸附引起的Cu_3Au（111）的分凝和Cu_2 O形成的势垒。用X射线光电子能谱结合同步辐射光源研究了超高温氧分子束（HOMB）氧化反应。从测得的O-吸收曲线的入射能量依赖性来看，O-2在Cu 3Au（111）上的解离吸附不如在Cu（111）上有效。Cu在Cu_3Au（111）、Cu_3Au（100）和Cu_3Au（110）上的吸附均为解离吸附。对于2.3 eV的HOMB，不能观察到Cu 2 O的明显生长，这表明富Au保护层阻止了O原子扩散到体中。基于密度泛函理论的计算结果表明，O在Cu_3Au（111）和Cu（111）上的吸附行为相同.对于扩散情况，偏析的Cu 3Au（111）中扩散到次表面的势垒高于Cu（111）中。这表明Cu 3Au（111）中析出的富金层起着保护层的作用。
We report results of the segregation induced by the adsorption of O-2 and the barrier of the formation of Cu2O in Cu3Au(111) with an experimental and theoretical approach. Oxidation by a hyperthermal O-2 molecular beam (HOMB) was investigated by X-ray photoemission spectroscopy in conjunction with a synchrotron light source. From the incident-energy dependence of the measured O-uptake curve, dissociative adsorption of O-2 is less effective on Cu3Au(111) than on Cu(111). The dissociative adsorption is accompanied by the Cu segregation on Cu3Au(111) as well as on Cu3Au(100) and Cu3Au(110). The obvious growth of Cu2O for a 2.3 eV HOMB cannot be observed and it suggests that the Au-rich protective layers prevent the diffusion of O atoms into the bulk. The theoretical approach based on density functional theory indicates that O adsorption shows the same behavior on Cu3Au(111) and on Cu(111). For the diffusion case, the barrier to diffuse into the subsurface in segregated Cu3Au(111) is higher than in Cu(111). This indicates that the segregated Au-rich layer in Cu3Au(111) works as a protective layer.