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First-principles Study of PdAu Segregation with CO Coverage

Published online by Cambridge University Press:  31 January 2011

Bin Shan ,
Jangsuk Hyun ,
Neeti Kapur  and
Kyeongjae Cho
Bin Shan
Affiliation:
stanfordbshan@hotmail.comstanfordbshan@yahoo.com, Nanostellar Inc., Computational Nanoscience Division, Redwood City, California, United States
Jangsuk Hyun
Affiliation:
jshyun@nanostellar.com, Nanostellar Inc., Computational Nanoscience Division, Redwood City, California, United States
Neeti Kapur
Affiliation:
nkapur@nanostellar.com, Nanostellar Inc., Computational Nanoscience Division, Redwood City, California, United States
Kyeongjae Cho
Affiliation:
kjcho@utdallas.edu, University of Texas at Dallas, Materials Science, Richardson, Texas, United States
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Abstract

Alloying has been one of the strategies to develop alternatives to Pt based CO oxidation catalyst. PdAu bimetallic alloy has recently been shown to have better reactivity and thermal stability toward CO oxidation for diesel engine applications as compared to pure metal catalysts. The key factor for low temperature light off in diesel engine catalysis is reactivity of alloy catalysts under CO environment, which in turn depends on the alloy surface composition and morphology. We explored the segregation processes in bimetallic Pd-Au alloy using first-principles calculations, assisted by a Monte-Carlo (MC) scheme that combines an improved Embedded Atom Method (EAM) and an atomistic treatment for adsorbed CO molecules for searching low energy states. Our simulation results show that PdAu surface changes from Au-rich to Pd-rich with increase in CO coverage up to 0.75 ML, beyond which additional CO adsorption is no longer favorable. A quantitative relationship between CO coverage and Pd concentrations on the surface is also revealed.

Keywords

AuPdcatalytic
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1177: Symposium Z – Computational Nanoscience–How to Exploit Synergy between Predictive Simulations and Experiment , 2009 , 1177-Z02-06
Copyright
Copyright © Materials Research Society 2009

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