2006 Fiscal Year Final Research Report Summary
Theoretical investigation of the low temperature catalytic activities and the electronic structures for gold and integrated precious metal clusters
| Project/Area Number |
16350011
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Osaka University |
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Principal Investigator |
OKUMURA Mitsutaka Osaka University, Graduate School of Science, Department of Chemistry, Associate Professor, 理学研究科, 助教授 (40356712)
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| Project Period (FY) |
2004 – 2006
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| Keywords | gold cluster / iridium cluster / surface adsorption / cluster size effect |
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| Research Abstract |
For, precious metal clusters, theoretical investigations were carried out in order to examine the relationship between the electronic states and the catalytic activities for them
Hybrid density functional calculations have been carried out for AuO_2, AuCO, Au13, Au_<13>O_2, Au_<13>CO, Au_<13>H_2 and Au_<55> clusters to discuss the catalytic behavior of Au clusters with different sizes and structures for CO oxidation. From these calculations, it was found that O_2 and CO could adsorb onto several Au model systems. Especially, icosahedral Au_<13> cluster has a relatively weak interaction with O_2 while both icosahedral and cubooctahedral Au_<13> clusters have interactions (_20 kcal/mol) with CO. These findings suggest that the surfaces of the Au clusters are the active sites for the catalytic reactions on the supported and unsupported Au catalysts.
For Ir clusters, Hybrid DFT calculations have also been carried out. The results of Ir model clusters show that the surface atoms of the Ir_<13> cluster have small negativecharges and the clusters have strong interactions with adsorbates.
In order to examine the moisture effect for CO oxidation over Au catalysts, ab initio calculations have been carried out for Au_<10>, Au_<10>-H_2O, Au_<10>-O_2, and Au_<10>-H_2 O-O_2 model clusters. The results show that all the Au10 clusters examined have a weak interaction with H_2O and neutral and negatively charged Au_<10> clusters have a weak interaction with O_2. Moreover, it is also found that the negative charge densities of O_2 were greatly increased in the case of the coadsorption of O_2 and H_2O on the surface of the negatively charged Au_<10>. These findings suggest that the presence of H_2O enhances the activation of O_2 on the surface of an Au cluster.
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Research Products
(41 results)
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[Journal Article] _2005
Author(s)
M.Okumura
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Journal Title
Applied Catalysis A, 291
Pages: 37-44
Description
「研究成果報告書概要(欧文)」より
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[Book] 物性量子化学入門2004
Author(s)
奥村光隆, 山口 兆
Total Pages
288
Publisher
講談社サイエンティフィック
Description
「研究成果報告書概要(和文)」より
