Ordering and Oxygen Adsorption in Au鈥揚t/Pt(111) Surface Alloys

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• 作者：Wei Chen ; David Schmidt ; William F. Schneider ; C. Wolverton
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：September 15, 2011
• 年：2011
• 卷：115
• 期：36
• 页码：17915-17924
• 全文大小：1040K
• 年卷期：v.115,no.36(September 15, 2011)
• ISSN：1932-7455

文摘

Bimetallic surface alloys are considered a promising type of catalyst for improved activity and selectivity. Using first-principles density functional calculations and the cluster expansion (CE) method, we have studied the surface structure and ordering of a mixed Au鈥揚t surface layer on Pt(111). Even though the Au鈥揚t system is well-known to phase-separate in the bulk, we predict a series of T = 0 K energetically stable, laterally ordered striped structures in the Au鈥揚t(111) surface. The formation of such ordered structures is the result of a competition between the strain relaxations (favoring short-period stripe ordering) and the unfavorable Au鈥揚t bonds at stripe interfaces (favoring long-period phase separation). We have also investigated the oxygen adsorption on these ordered structures and a disordered Au鈥揚t(111) surface alloy. The disordered surface is modeled by a two-dimensional special quasirandom structure (SQS) that mimics the pair and triplet correlation functions of a disordered binary distribution. The oxygen binding energy is highly correlated with the number and type of the nearest neighbor metal surface atoms to the adsorbed oxygen.