Tuning electronic properties of novel metal oxide nanocrystals using interface interactions: MoO3 monolayers on Au(1Â 1Â 1)

We report experimental and theoretical investigations of monolayer MoO3 nanocrystals grown on Au(1 1 1), in contrast to the bilayered structure of the bulk oxide crystal. The Au surface acts as the other half of the bilayer by satisfying local bonding requirements through charge redistribution at the interface. Epitaxy with the Au lattice is achieved through the ability of the Mo-O bonds to rotate about one another. The oxide layer becomes semimetallic as it strains to enhance bonding with the Au substrate. This flexibility of the oxide lattice suggests the possibility of tuning electronic properties of transition metal oxides via interface interactions. The effects of electronic structure on the surface chemistry of oxides are in turn illustrated by H adsorption energetics on MoO3.