First-principles studies for CO and O2 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 [CO2+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 -> CO2+O, in which the reaction barrier is only about half electron volts. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3455714]