Chemical Synthesis and Characterization of ZnO–TiO2 Semiconductor Nanocomposites: Tentative Mechanism of Particle Formation

Abstract

The compounds of ZnO–TiO2 can combine the characteristics of the individual oxides which has allowed them to be used as photocatalysts in general, photodegradants in the degradation of dyes, photocatalytic oxidation of NOx, antimicrobial, among other applications. In this study, ZnO–TiO2 semiconductor nanocomposites were synthesized in a controlled way at low temperature. These samples of ZnO–TiO2 were characterized using thermal analysis (TDA/TGA), IR and UV–Vis absorption spectroscopies, X-ray diffraction, and scanning electron microscopy. The primary particles showed a nanometric size (< 100 nm) and spheroidal morphology. All samples presented zincite as the main crystalline phase. When Ti4+ was added, the peaks of the diffractograms shifted slightly with respect to pure ZnO. This indicates the formation of a solid solution. Zn2TiO4 was observed in doped ZnO samples treated at 700 °C. The UV–Vis absorption spectra showed a band in the range between 350 and 425 nm, with a maximum around 375 nm (3.31 eV). With the addition of Ti4+, the nanocomposites showed a better absorbance in the visible range. Considering the nature of the synthesis process used, a mechanism was proposed to explanation of the formation of Nanocomposites.