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 ~ 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 overwhelmingly 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.