Chapter Eight - Material Dependence of Water Interactions with Metal Oxide Nanoparticles: TiO2, SiO2, GeO2, and SnO2

Abstract

Surface interactions of water with nano-TiO2 and structurally related group IV metal dioxide nanoparticles have been investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The investigated clusters include 46 and 92 unit models of TiO2 (i.e., (TiO2)46 and (TiO2)92) of the three low-energy polymorphs of TiO2: anatase, rutile, and brookite. The investigation also includes studies of corresponding rutile-type clusters of three structurally related forms of group IV oxides: SnO2, GeO2, and SiO2. The calculations demonstrate the strong influence of water surface adsorption on several important nanoparticle properties including structure, charge distribution, and electronic structure for all investigated materials. Significant differences between the various materials are also revealed by the calculations, including an unusual stability of the electronic structure of TiO2 in the environment of particular relevance for its photoelectrochemical and photocatalytic applications.