Positive charge States and possible polymorphism of gold nanoclusters on reduced ceria.

The catalytic properties of Au/CeO(2) systems are sensitive to the nature of Au clusters; however, atomic information on Au clusters is sparse. In this work, we use density functional theory to investigate the nucleation of small Au clusters (up to Au(11)). By depositing Au atoms one by one at a reduced CeO(2){111} surface, we present detailed nucleation patterns. Although relatively small in size, the nanoclusters obtained exhibit interesting characteristic features. In addition to the face-centered cubic (fcc) geometry, reminiscent of bulk Au, we also find the existence of novel hexagonal close-packed (hcp) structures. Furthermore, the facets of the nanoclusters are versatile, comprising {111}/{100} combinations for the fcc-like clusters and {10(1)1}/{0001} combinations for the hcp-like. Electronically, the contact layer Au atoms that bond with surface O atoms are positively charged, which could have significant implications in catalysis.