Visible light responsive rutile TiO2 photocatalysts mixed with cement: Enhancement effect driven by TiO2/cement interfaces

Naked rutile TiO2 as well as commercial rutile TiO2 with Al2O3 and ZrO2 capping layers both with particle size of 100 similar to 300 nm were tested as additives to cements with a goal of fabricating building materials that can remove harmful NO and volatile organic compounds from the atmosphere. The commercial TiO2 is widely used as pigment and very cost-effective. Generally, the activities of photocatalysts were enhanced by mixing with cement. Moreover, originally less active capped TiO2 yielded comparable or even superior activity than bare rutile in the composite with cement. Our results suggest that the activity of the photocatalyst/cement is over-whelmingly governed by the active TiO2/cement interfaces rather than the intrinsic surface structural properties of photocatalysts. Based on various analyses results including x-ray absorption spectroscopy, emphasis is placed on the unique adsorption properties of the interface sites, which are driven by the lattice distortion of TiO2 at this interface.