| Budget Amount *help |
¥13,600,000 (Direct Cost: ¥13,600,000)
Fiscal Year 2006: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2005: ¥5,600,000 (Direct Cost: ¥5,600,000)
Fiscal Year 2004: ¥6,000,000 (Direct Cost: ¥6,000,000)
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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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