High photoactive TiO₂/SnO₂ nanocomposites prepared by laser pyrolysis

Highlights: • TiO₂/SnO₂ nanocomposites were synthesized by the single step laser pyrolysis. • TiCl₄, SnCl₄ and O₂ from air were the precursors and C₂H₄ was the sensitizer. • Different Sn (1.1–4.8 at.%) concentrations were found. • TiO₂/SnO₂ samples have a lower bandgap energy (Eg = 2.9 eV) and better UV photoactivity as compared with the P25 Degussa. - Abstract: 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.