First-principles studies for CO and O(2) on gold nanocluster.

First-principles calculations are performed to study the interaction of gold nanocluster Au(55) with small molecules CO and O(2). We find that the adsorption energy of CO on Au(55) is among 0.5-0.7 eV at different sites and [CO+O(2)] can be coadsorbed on Au(55). Comparisons between Au(55) and Au(32) show that the adsorption energy not only depends on the size of the cluster but also on the geometry of the cluster. Similar with smaller cluster (Au(8) and Au(32)), the energy difference between [CO+O(2)] and [CO(2)+O] on Au(55) is much larger than that in the free gas. Our calculations indicate that the nanocluster Au(55) can enhance the reaction process, CO+O(2)-->CO(2)+O, in which the reaction barrier is only about half electron volts.