Synthesis and characterization of the composite of SnO2 nanoparticles coated on SiO2 microspheres

The SnO2 nanoparticles coated on SiO2 microspheres were prepared with the hydrous tin chloride, NH3·H2O and the slurry of amorphous silica microspheres in an aqueous medium. X-ray powder diffraction (XRD), Fourier transformed infrared (FTIR) spectra, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrum (XPS), and UV-vis spectrophotometer were used to characterize the SiO2-SnO2 core-shell structured particles. The XRD of the SnO2 nanoparticles coated on SiO2 microspheres yields diffraction peaks corresponding to the cassiterite SnO2 phase. The FE-SEM and TEM images show that the SnO2 nanoparticles (diameter 3.9 nm) coated SiO2 surface as thin layers or nanoclusters, depending on the reactant concentration. UV-vis spectrum shows an absorption edge at around 315 nm, which is markedly blue-shifted compared to that of bulk SnO2 (350 nm).