Structures and stabilities of gold oxide films on gold surfaces in O2 atmosphere

The structures and stabilities of gold oxide films on gold surfaces in O2 atmosphere are investigated by a combination of thermodynamics and density functional theory (DFT) calculations. It is predicted that the stability of a gold oxide film on a gold surface depends on the formation energy of an isolated gold oxide film, the lattice mismatch, and the oxygen coverage. These predictions are subsequently confirmed by DFT calculations and thermodynamic analysis. The calculation results also display that the dual chain structure is stable on most gold surfaces at low oxygen chemical potential except on a Au(111) surface, on which the graphene-like 12 MR structure is more stable. While at the high oxygen chemical potential, the connected dual chain structure is the most stable structure because of the highest oxygen coverage and the lowest formation energy. The phase transformation point from the dual chain structure to the connected dual chain structure on a gold surface depends on the lattice mismatch between the connected dual chain and a gold surface.