Segregation and stability at Pt₃Ni(1 1 1) surfaces and Pt₇₅Ni₂₅ nanoparticles

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• 作者：Ben Fowler ; Christopher A. Lucas ; Ahmed Omer ; Guofeng Wang ; Vojislav R. Stamenkovi&#x107 ; Nenad M. Markovi&#x107
• 关键词：Electrocatalysis ; Single crystal alloy ; X-ray scattering ; Surface segregation ; Nanoparticles
• 刊名：Electrochimica Acta
• 出版年：2008
• 期刊代码：30_00134686
• 类别：ch
• 出版时间：1 September 2008
• 卷：53
• 期：21
• 页码：6076-6080
• 文件大小：612 K

摘要

Using in situ surface X-ray diffraction we have determined the atomic structure and stability of a Pt₃Ni(1 1 1) surface in the electrochemical environment. Surface segregation leads to a pure Pt(1 1 1) skin with enrichment of Ni in the sub-surface atomic layer that determines the surface electronic structure. The Pt-skin surface exhibits inward relaxation upon the adsorption of oxygenated species and this explains the surface stability compared to pure Pt(1 1 1). Using Monte Carlo calculations it is shown that nanoparticles with the same surface composition and stochiometry are energetically stable.