Infra-red studies of rutile surfaces: Part 3.—Adsorption of water and dehydroxylation of rutile

Abstract

There are two forms of adsorbed molecular water present on rutile surfaces under ambient conditions. One form is hydrogen bonded to surface hydroxyl ions and the other is held as a coordinating ligand to surface cations.3 Out-gassing at 300 K overnight removes only the hydrogen-bonded species. Quantitative measurements of the surface concentrations of the coordinately-bonded species and the water dissociatively adsorbed as surface hydroxyl ions suggest that the surface of the pure rutile microcrystals used is composed of three crystal planes, viz.(110), (100) and (101) in the ratio 3 : 1 : 1, as suggested previously.1 Spectroscopic studies of room temperature rehydroxylation of partly dehydroxylated rutile surfaces shows that coordinately-bonded molecular water is present on the surface before the dissociative adsorption to give surface hydroxyl ions is complete.