Characterization and activity of visible light-driven TiO2 photocatalysts co-doped with nitrogen and lanthanum

Nitrogen and lanthanum co-doped titania photocatalysts were prepared by a modified sol-gel process with urea and lanthanum nitrate doping precursors and characterized by various techniques including XRD, FTIR, TEM, EDS, and UV-Vis DRS. The average crystallite size was ca. 12-15 nm as calculated from XRD patterns, and anatase was the dominant crystalline type in the as-prepared samples. The UV-Vis DRS of the samples revealed significant absorption within the range of 400-500 nm. The optimum composition of N(0.020)La(0.012)TiO2 exhibited the highest photocatalytic activity for degradation of methyl orange (MO) aqueous solution under simulated sunlight. The percent degradation of MO was ca. 97% for N(0.020)La(0.012)TiO2 under simulated sunlight irradiation for 9 h. The enhanced photocatalytic activity was ascribed to the synergistic effects of the nitrogen and lanthanum co-doping.