The adsorption of water molecules on the flat, close-packed surfaces of metals was thought to be simple and well understood. The first layer partially covers the surface and binds through the lone electron pairs of the oxygen atoms, whereas the next layer attaches via hydrogen bonds to these water molecules. However, recent results have suggested that, on the (0001) surface of ruthenium, water can partially dissociate and form a mixed network of water and hydroxyl molecules.
Ogasawara et al. have combined soft x-ray spectroscopy and density functional theory calculations to show that, on the (111) surface of platinum, half of the water molecules of the first layer bind through their lone pairs, but the other half bind to the metal surface through their hydrogen atoms. The presence of unusual metal-hydrogen bonds to water molecules, in the absence of free hydroxyl, challenges current models of water adsorption on metals and should help further the understanding of processes such as corrosion and the photodissociation of water. -- PDS
Phys. Rev. Lett. 89, 276102 (2002).
