Dynamic Restructuring Induced Oxygen Activation on AgCu Near-Surface Alloys
Dynamic Restructuring Induced Oxygen Activation on AgCu Near-Surface Alloys
复制标题
AgCu 近表面合金的动态重组诱导氧活化
DOI：
10.1021/acs.jpclett.0c00887
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Sykes, E. Charles
中科院分区：
文献类型：
--
作者：
Cramer, Laura A.;Liu, Yilang;Deshlahra, Prashant;Sykes, E. Charles
最近的研究表明，添加Cu到Ag催化剂通过提高环氧化催化剂的总体选择性来改善其环氧化性能。我们制备了AgCu近表面合金，并利用扫描隧道显微镜获得了O2解离的原子图像。这些数据揭示了更高的解离吸附概率的O2在AgCu比在Ag（111），和密度泛函理论（DFT）证实，O2解离势垒是0.17 eV的低合金。令人惊讶的是，我们发现，在最初缓慢吸收O2后，粘附概率呈指数级增加。进一步的DFT计算表明，表面氧反转的AgCu，稳定在Ag层中的Cu原子的偏析能量。这些单一的Cu原子在Ag表面被发现显着降低O2解离势垒。总之，这些结果解释了非线性效应的激活O2在这个催化相关的表面合金。
Recent studies have shown that the addition of Cu to Ag catalysts improves their epoxidation performance by increasing the overall selectivity of the bimetallic catalyst. We have prepared AgCu near-surface alloys and used scanning tunneling microscopy to gain an atomistic picture of O2dissociation on the bimetallic system. These data reveal a higher dissociative sticking probability for O2on AgCu than on Ag(111), and density functional theory (DFT) confirms that the O2dissociation barrier is 0.17 eV lower on the alloy. Surprisingly, we find that, after a slow initial uptake of O2, the sticking probability increases exponentially. Further DFT calculations indicate that surface oxygen reverses the segregation energy for AgCu, stabilizing Cu atoms in the Ag layer. These single Cu atoms in the Ag surface are found to significantly lower the O2dissociation barrier. Together, these results explain nonlinear effects in the activation of O2on this catalytically relevant surface alloy.