An investigation on photocatalytic activities of mixed TiO2-rare earth oxides for the oxidation of acetone in air

Abstract

The photocatalytic activities of the mixtures of TiO2 (P25) with three rare earth oxides were investigated. The effects of the rare earth oxide contents and calcination temperature on the photocatalytic activities were studied. The results reveal that the mixtures of TiO2 with La2O3 (0.5 wt.%) or Y2O3 (0.5 wt.%) calcined at 700 °C or 650 °C exhibit higher photoactivity than pure TiO2 (P25) for the oxidation of acetone. On the other hand, the mixtures of TiO2 with CeO2 have lower photoactivity than pure TiO2. Experimental results of polycrystalline X-ray diffraction, photoexcited transient absorption decay and zeta potential measurements show that the presence of these rare earth oxides can inhibit anatase to rutile transformation at elevated temperatures. The lower photocatalytic activity of TiO2/CeO2 mixtures can be explained by the fast recombination rate of photogenerated electron-hole pairs and high isoelectric point in terms of pH value. The preparation method of these mixtures is also described.