Density-functional based modeling of the intermediate in the water production reaction on Pt(111)

A model based on density-functional calculations has been developed for the overlayer formed by dissociation of water on an oxygen covered Pt(111) surface. The directional dependent interaction within the overlayer is treated by means of a lattice model of Ising type. Stable large length scale structures are found for two compositions proposed in the literature: a hydroxyl-water and a hydroxyl-hydrogen mixed composition, respectively. The water containing composition produces an overlayer structure in very good agreement with the structures seen in scanning tunneling microscopy experiments.