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Theoretical Investigation on the Structure and Electronic Properties of Hydrogen- and Alkali-Metal-Doped Gold Clusters and Their Interaction with CO: Enhanced Reactivity of Hydrogen-Doped Gold Clusters

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journal contribution
posted on 15.10.2009, 00:00 by Naresh K. Jena, K. R. S. Chandrakumar, Swapan K. Ghosh
The electronic structure and properties of pristine gold clusters Aun as well as the alkali-metal- and hydrogen-atom-doped clusters Aun−1X, where n = 2−8 and X = Li, Na, and H, have been investigated. The dopant atoms are interesting from the perspective that they have similar outer electronic configuration in the form of a single valence electron like the gold atom. Electronic properties such as ionization potential, electron affinity, binding energy, HOMO−LUMO gap, and hardness parameters are found to exhibit a regular odd−even oscillatory pattern with variation of the cluster size. Our results reveal that the role of the hydrogen atom in modulating the structural and electronic properties of gold clusters is antagonistic to that of the alkali-metal atoms. The HOMO−LUMO gaps for the hydrogen-doped gold clusters are found to be much higher than the pristine and the alkali-metal-atom-doped clusters. In addition, we have also made an extensive study to investigate the important role of the impurity atoms, hydrogen and alkali-metal atoms, on the adsorption of CO molecules by the doped gold clusters. An enhancement of the CO-adsorption energy has been observed for the gold clusters doped with a hydrogen atom rather than for the corresponding alkali-metal-doped clusters and the enhancement is found to be more pronounced for the higher clusters in the series. An interesting observation is that there is as high as a 5-fold increase in the interaction energy of CO with Au7H cluster as compared to its pristine counterpart Au8.

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