Isomerization in Gold Clusters upon O2 Adsorption

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• 作者：Min Gao ; Daisuke Horita ; Yuriko Ono ; Andrey LyalinSatoshi Maeda ; Tetsuya Taketsugu
• 刊名：Journal of Physical Chemistry C
• 出版年：2017
• 出版时间：February 9, 2017
• 年：2017
• 卷：121
• 期：5
• 页码：2661-2668
• 全文大小：505K
• ISSN：1932-7455

文摘

A systematic investigation is performed on structural transformations in small neutral gold clusters (Au₃–Au₁₂) induced by O₂ adsorption, with the use of the fully automated reaction path search techniques, i.e., anharmonic downward distortion following (ADDF) and artificial force induced reaction (AFIR) methods, implemented in the global reaction route mapping (GRRM) program. For each size of Au cluster, the most stable structure, low-energy isomers, and a network of isomerization pathways are determined. The located Au_n–O₂ adsorption forms can be classified into two groups: η¹-Au_nO₂, where only one oxygen atom is adsorbed on Au_n, and η²-Au_nO₂, where both oxygen atoms are adsorbed on Au_n in a bridged manner. These two adsorption forms can be transformed to each other with a low barrier. The isomerization pathways of gold clusters upon O₂ adsorption are compared with those obtained for the pure gold clusters without O₂. It is demonstrated that O₂ adsorption promotes structural transformations in gold clusters considerably by lowering the isomerization barriers. The presence of the unpaired electron is a necessary condition for O₂ adsorption in the η¹-Au_nO₂ form, as well as the subsequent cluster isomerization and the O–O bond activation. These conclusions are consistent with the recent experimental results by Fielicke et al.