High photoactive TiO2/SnO2 nanocomposites prepared by laser pyrolysis

TiO2/SnO2 nanocomposites have been prepared by laser pyrolysis of volatile TiCl4 and SnCl4 precursors introduced together or separately in the reaction zone in the presence of air as oxidant and ethylene as sensitizer. Prior to the obtaining of TiO2/SnO2 nanocomposites with the different Sn concentrations (1.1-4.8 at.%), the best experimental conditions were identified for preparing pure anatase phase TiO2 samples considered as photoactive reference sample. The TiO2/SnO2 composites were characterized using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and UV-vis diffuse reflectance spectroscopy (DRS) techniques. The structural results show the presence of both TiO2 main phases: anatase (65-82% − the majority one) and rutile, as well as of small amounts of SnO2 tetragonal phase, all those with mean crystallite dimensions in the 8-22 nm range. Laser synthesized TiO2/SnO2 samples have a lower band gap energy and some of them (containing 1.8 or 4.8 at.% Sn) show higher photoactivity in the process of Methyl Orange solutions UV discoloration when compared with the P25 Degussa commercial sample.