Atomic Oxygen Adsorption on Au(111) Surfaces with Defects

We study the equilibrium structures for the adsorption of atomic oxygen on Au(111) surfaces containing defects such as vacancies and steps, using first-principles density functional theory calculations. We considered the gold-oxygen interaction as a function of surface vacancy concentration, the interaction with 1,2 and 4 gold adatoms (the latter number arranged in groups that represent 2D or 3D gold islands), the interaction at steps, and finally, the effect of strain. We find that there is an attractive interaction between oxygen atoms and vacancies on the surface, which lowers the cost to create a surface vacancy by 0.20 eV, but the interaction between oxygen and gold adatoms is repulsive. We conclude that the strength of the oxygen-gold interaction is correlated with the coordination number of the gold atom to which the oxygen is bound.