One-step flame synthesis ofSnO2/TiO2composite nanoparticles for photocatalytic applications

Abstract

SnO2/TiO2composite nanoparticles have been synthesized in a single-step by feeding evaporated precursor mixtures into an atmospheric pressure diffusion flame. Particles with controlled Ti: Sn ratios were produced at various flow rates of oxygen, and the resulting powders were characterized by BET surface area analysis, XRD, TEM, EDAX and UV-Vis spectroscopy. For the lowest concentration (3.4 mol %) ofSnO2employed in this study anatase phase ofTiO2is stabilized, while segregation ofSnO2is seen at medium (6.9 to 12.4 mol %) and high concentrations (20.3 mol %). Though the equilibrium phase diagram predicts complete solubility of one oxide in another at all compositions, segregation ofSnO2phase is observed which is explained by the usage of diffusion flame in the present study. The particle formation mechanism ofSnO2/TiO2composites is proposed basing on the single component aerosol formation. Photocatalytic activity of the composite particles is tested for the degradation of methylene blue and is compared with pureTiO2synthesized under similar conditions. Improved photocatalytic activity of the composite particles is attributed to the stabilized anatase phase and better charge separation due to the coupling ofTiO2andSnO2within the composite nanoparticles.