Photoluminescence of La/Ti mixed oxides prepared using sol-gel process and their pCBA photodecomposition

La/Ti mixed oxides with weight ratios of 1:9, 2:8, 3:7, and 4:6 were prepared by sol-gel method. The photocatalytic activity of La/Ti oxides was evaluated based on the pCBA photodecomposition. The catalyst samples were characterized by XRD, TEM, DRS, BET, and photoluminescence (PL) spectra. Particles of the La/Ti-mixed oxides showed the diameter of about 7 nm. We found that 30% doping of lanthanum ions on the TiO2 powders induced the highest pCBA (4-chlorobenzonic acid) photodecomposition in these experimental conditions. The order of its photoactivity was as following: 30 > 20 > 0 > 10 > 40 wt%, which was the same for PL tendency. Also, PL spectra intensity increased with calcination temperature from 500 to 600 degrees C, then decreased at 700 degrees C. Phtotcatalytic activity followed the trend of the PL spectra intensity. The modification of TiO2 surface by lanthanum ion made it possible to enhance the photoactivity by retarding the recombination of photoexcited electron/hole pairs, in the result of the higher photoactivity in the stronger PL intensity. (c) 2006 Elsevier B.V. All rights reserved.