Pt surface segregation in bimetallic Pt3M alloys:: A density functional theory study

被引：201

作者：

Ma, Yuguang ^{[1
]}

Balbuena, Perla B. ^{[1
]}

机构：

[1] Texas A&M Univ, Dept Chem Engn, College Stn, TX 77843 USA

来源：

SURFACE SCIENCE | 2008年 / 602卷 / 01期

关键词：

density functional calculations; surface energy; surface segregation; surface structure; morphology; roughness; topography;

D O I：

10.1016/j.susc.2007.09.052

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

A simplified 5-layer slab model is used to study Pt segregation at Pt3M(1 1 1) surfaces (M = Ag, Au, Co, Cr, Cu, Fe, Ir, Mn, Mo, Ni, Pd, Re, Rh, Ru, Ti, V). The calculated segregation energies are generally in good agreement with the experimental results. However, for Pt3Ti(1 1 1) and Pt3Mn(1 1 1), the model is unable to give the correct prediction because the experimental subsurface compositions are very different from those of the model. Pt segregation is found to be correlated with the subsurface atomic structure, the size of metal atoms and the surface energy. Interestingly, the calculations show that the displacement of M atoms at the topmost Pt3M layer can be used to predict the surface segregation trend. The local geometries for the segregation and non-segregation structures are carefully compared and the surface geometric effect on the oxygen reduction reaction (ORR) activity is discussed. In particular, it is determined that the enhanced ORR activity for the Pt-skin surfaces of Pt3Ni(1 1 1) and Pt3Co(1 1 1) alloys are not caused by geometric effects. (C) 2007 Elsevier B.V. All rights reserved.

引用

页码：107 / 113

页数：7

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