Water Adsorption on bcc Iron Surfaces

Water adsorption on iron surfaces is intensively studied due to the importance of this process in understanding of corrosion and reduction of iron oxides by hydrogen, and in electrochemistry. We review theoretical aspects of the adsorption phenomena of water molecules that have been studied for stoichiometric and defected Fe surfaces. It is found that the H 2 O molecule does not dissociate spontaneously neither on densely packed nor open low-index surfaces, instead it adsorbs flat with the oxygen atom on top of the surface Fe atom. At the defected surface H 2 O molecules prefer sites at the edge of the vacancy, not at the stoichiometric region of the surface. The influence of the van der Waals interactions on the adsorption binding energy and the geometry of the system is also discussed.