Reactivity of Oxygen Adatoms on Stepped Au(997) Surface toward NO and NO2

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• 作者：Zongfang Wu ; Yuekang Jin ; Lingshun Xu ; Qing Yuan ; Feng Xiong ; Zhiquan Jiang ; Weixin Huang
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：April 24, 2014
• 年：2014
• 卷：118
• 期：16
• 页码：8397-8405
• 全文大小：467K
• 年卷期：v.118,no.16(April 24, 2014)
• ISSN：1932-7455

文摘

Oxygen adatoms were prepared on stepped Au(997) surface consisting of (111) terraces and monatomic (111) steps by thermal decomposition of amorphous N₂O₄ multilayers, including O(a) on the (111) steps and O(a) adatoms and islands on the (111) terraces. Their structures and reactivities toward NO and NO₂ were investigated by means of thermal desorption spectroscopy, X-ray photoelectron spectroscopy, and low-energy electron diffraction. Oxygen adatoms interact with seven-coordinated Au atoms on the (111) steps more strongly than with nine-coordinated Au atoms on the (111) terraces. The stability of different types of O(a) species follows the order of O(a) on the (111) steps > O(a) adatoms on the (111) terraces > O(a) islands on the (111) terraces. O(a) species on both (111) steps and (111) terraces facilely react with NO to form chemisorbed NO₂(a) that desorbs from the surface at elevated temperatures. Less thermally stable O(a) species on Au surface was found to exhibit enhanced reactivity in the NO + O(a) reaction. O(a) species on Au(997) surface do not react with NO₂ but they suppress their chemisorption, and strong repulsive interactions exist between coadsorbed O(a) and NO₂(a). Due to the limited available sites on the (111) steps, NO₂(a) on the (111) steps are more facilely affected by the coadsorbed O(a) than those on the (111) terraces. These results help to fundamentally understand elementary surface reactions in NO_x-involved reactions catalyzed by Au catalysts.