ZnO-TiO2 nanocomposites synthesized by wet-chemical route: Study of their structural and optical properties

In this work, ZnO-TiO2 nanocomposites were synthesized using the polymerizable complex method. Their structural and optical characteristics were determined using IR, UV-Vis absorption and diffuse reflectance spectroscopies, X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence. The primary particles obtained were nanometric in size (< 100 nm) with a spheroidal morphology. All the samples presented zincite as the main crystalline phase. On adding the titanium, the diffractograms indicating the formation of a solid solution. The doped ZnO samples, treated at 700 degrees C, also presented Zn2TiO4. Independent of the heat treatment, the synthesized ZnO samples showed an energy gap value of similar to 3.2 eV. In the case of ZnO-TiO2 composites, treated at 500 degrees C, the gap value was of 3.28 eV (1% of Ti4+) and similar to 3.2 eV (5% of Ti4+). The photoluminescence results indicated the presence of defects in the structure, mainly of V-o, O-i, Zn-i and V-Zn depending on the temperature of the heat treatment to which the sample is subjected.