Photocatalytic activity of a surface-modified anatase and rutile titania nanoparticle mixture.

Photocatalytic activity of mixtures of anatase and rutile titania nanoparticles, both bare and treated via capillary condensation of a silica precursor, was investigated by following photodegradation of methylene blue by ultraviolet light in an aqueous solution. The best observed activity for the physically mixed nanoparticles was seen at an anatase to rutile mass ratio of 4:1. This mixture was subject to capillary condensation of tetraethyl orthosilicate (TEOS) at various saturation ratios, followed by reaction of TEOS to form silica. Treatment at a saturation ratio of 1.2 improved photoactivity over that of the physical mixture, a result attributed to enhanced interphase connectivity and increased methylene blue adsorption onto silica.