A shortcut for evaluating activities of TiO₂ facets: Water dissociative chemisorption on TiO₂-B (100) and (001)

By means of density functional theory (DFT) calculations, we study the water adsorption behavior on two common surfaces, (001) and (100) TiO ₂-B, which maintains the monoclinic structure as high as ∼550°C or higher in ambient conditions. The two surfaces show totally different activity for water dissociation. The dissociative chemisorption of water on TiO₂-B (100) is identified at both submonolayer and monolayer coverages, which indicates considerable reactivity. In contrast, the non-dissociative molecular adsorption of water is the most stable state on TiO₂-B (001) which suggests no special activity. Furthermore, we compare the structural features of different surfaces with diverse crystal structures, such as rutile, anatase, brookite, TiO₂-B etc. Keeping a close eye on the exposed atoms on the surface, we conclude a more general criterion for a quick evaluation of reactivities of different TiO₂ surfaces merely based on local surface structure features.