Interaction of CO, O, and CO2 with Cu cluster supported on Cu(1 1 1): a density functional theory study.

We performed density functional theory (DFT) based calculations to investigate the interaction of CO2 and its dissociated species (CO and O) on Cu3 cluster supported on Cu(1 1 1) (Cu3/Cu(1 1 1)) surfaces. Similar investigations were conducted on Cu(1 1 1) for purpose of comparison. In general, adsorption of CO and O are stronger on the cluster region than on the terrace region of Cu3/Cu and on the flat Cu surface. CO2, on the other hand, is weakly adsorbed on the surfaces. With reference to CO2 dissociation on Cu(1 1 1), we found that the cluster lowers the activation barrier and provides a more stable adsorption of the dissociated species. The presence of co-adsorbed CO in the cluster, however, will increase the activation energy. The variation in the activation barrier with the amount of CO is influenced by the stability of the O atom from the dissociated CO2. We further found that the adsorption energy of O atom is a possible descriptor for CO2 dissociation on the cluster region. The Cu cluster supported on Cu surface could be a promising catalyst for CO2 related reactions based on the lower activation energy for CO2 dissociation on the system than on Cu(1 1 1).