Redox-Mediated Reconstruction of Copper during Carbon Monoxide Oxidation
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- 作者：Fang Xu ; Kumudu Mudiyanselage ; Ashleigh E. Baber ; Markus Soldemo ; Jonas Weissenrieder ; Michael G. White ; Dar铆o J. Stacchiola
- 刊名：Journal of Physical Chemistry C
- 出版年：2014
- 出版时间：July 24, 2014
- 年：2014
- 卷：118
- 期：29
- 页码：15902-15909
- 全文大小：443K
- ISSN：1932-7455
文摘
Copper has excellent initial activity for the oxidation of CO, yet it rapidly deactivates under reaction conditions. In an effort to obtain a full picture of the dynamic morphological and chemical changes occurring on the surface of catalysts under CO oxidation conditions, a complementary set of in situ ambient pressure (AP) techniques that include scanning tunneling microscopy, infrared reflection absorption spectroscopy (IRRAS), and X-ray photoelectron spectroscopy were conducted. Herein, we report in situ AP CO oxidation experiments over Cu(111) model catalysts at room temperature. Depending on the CO:O2 ratio, Cu presents different oxidation states, leading to the coexistence of several phases. During CO oxidation, a redox cycle is observed on the substrate鈥檚 surface, in which Cu atoms are oxidized and pulled from terraces and step edges and then are reduced and rejoin nearby step edges. IRRAS results confirm the presence of under-coordinated Cu atoms during the reaction. By using control experiments to isolate individual phases, it is shown that the rate for CO oxidation decreases systematically as metallic copper is fully oxidized.