Photocatalytic properties of composites containing titania nanoparticles on submicron Y2O3 spheres

The photocatalytic properties of TiO₂/Y₂O₃ composites prepared by coating with anatase and η-TiO₂ nanoparticles, Degussa P25, and Hombifine N by simultaneous dispersing Y₂O₃ and TiO₂ powders in a weakly alkaline aqueous medium (procedure I) or Y₂O₃ powder in an acidic titanium-containing hydrosol (procedure II) have been studied for the first time. The results demonstrate that, after sonication, the η-TiO₂/Y₂O₃ and anatase/Y₂O₃ composites have almost identical photocatalytic activities (PCAs), which are however lower than those of anatase and η-TiO₂, whereas the PCA of the samples prepared by procedure II is comparable to that of nano-TiO₂ under UV irradiation and exceeds the activity of Degussa-N,S (Degussa P25 annealed with thiourea) exposed to visible light. The highest PCA is offered by a TiO₂〈Cl〉/Y₂O₃ composite modified with the products of titanium tetrachloride hydrolysis in air.