Abstract: Modification of nanocrystalline coupled semiconductor ZnO-TiO2 by means of La3+doping using the sol-gel method was investigated. Thermogravimetry-differential scanning calorimetry, scanning electron microscopy,X-raydiffraction, and Raman spectroscopy were employed to analyse the structure and morphology of La3+/ZnO-TiO2. The degradation of reactive red K-2BP was used to evaluate the photocatalytic activity of the catalyst under UV-lamp (253.7 nm, 20 W) irradiation. Effects of La3+doping concentration and calcination temperature on photocatalytic activity were investigated at a fixed photocatalyst amount and air flow rate. The results showed that La3+doping caused an increase in crystal transformation temperature, a strong blue shift of diffraction peaks, and a decrease in grain size. The reactive red K-2BP could be fully degraded within 40 min when La3+doping content was 0.5% and calcination temperature was 500 ℃. Under these conditions, the apparent absorption coefficient reached 0.182 min-1, which was 1.4 times as large as coupled semiconductor ZnO-TiO2.

Key words: lanthanum, zinc oxide, titania, coupled semiconductor, rare-earth doping, photocatalytic activity, reactive red