Promoter Effect of Early Stage Grown Surface Oxides: A Near-Ambient-Pressure XPS Study of CO Oxidation on PtSn Bimetallics

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• 作者：Yvette Jugnet ; David Loffreda ; C茅line Dupont ; Fran莽oise Delbecq ; Eric Ehret ; Francisco J. Cadete Santos Aires ; Bongjin S. Mun ; Funda Aksoy Akgul ; Zhi Liu
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2012
• 出版时间：December 20, 2012
• 年：2012
• 卷：3
• 期：24
• 页码：3707-3714
• 全文大小：525K
• 年卷期：v.3,no.24(December 20, 2012)
• ISSN：1948-7185

文摘

The knowledge of the catalyst active phase on the atomic scale under realistic working conditions is the key for designing new and more efficient materials. In this context, the investigation of CO oxidation on the bimetallic Pt₃Sn(111) surfaces by near-ambient-pressure X-ray photoelectron spectroscopy and density functional theory calculations illustrates how combining advanced methodologies allows the determination of the nature of the active phase. Starting from 300 K and 500 mTorr of oxygen, the progressive formation of surface oxides is observed with increasing temperature: SnO, PtO units first, and SnO₂, PtO₂ units afterward. For CO oxidation on the (2 脳 2) surface, the activity gain is assigned to the build-up of ultrathin domains composed of SnO and SnO₂ units. The formation of these early stage surface oxides is entirely supported by a density functional theory analysis. More generally, this study demonstrates how the catalyst surface oxidation and transformation can be better controlled by a relevant choice of environmental conditions.

Keywords:

alloy; single crystal; oxidation; CO oxidation; near-ambient-pressure XPS; DFT