Zinc Doped TiO2 Mesoporous Hollow Microspheres: Preparation and Photocatalytic Activity

Zinc doped TiO2 mesoporous hollow microspheres were synthesized based on sol-gel method by using SiO(2)as the template, tetra-n-butyl titanate as Ti source and Zinc nitrate hexhydrate as Zinc source. The prepared samples were characterized by means of X-ray diffraction (XRD), low temperature nitrogen adsorption-desorption (BET surface area), transmission electron microscope (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Methyl blue dye was used as a target dye to evaluate the photocatalytic activity of the samples. The results show that microspheres are hollow after removing the SiO2 template using an aqueous solution of NaOH and it takes more than 90 mm to completely remove the SiO2 template. The thickness of the TiO2 shell is about 20 nm. The dropping rate of tetra-n-butyl titanate solution plays an important role in the structure. When the dropping time exceeds 15 min, the obtained hollow microspheres have clear structure. The XRD results indicate that pure hollow microspheres and Zinc doped hollow microspheres exist in the form of anatase. When the doping molar ratio of Zn2+ to tetra-n-butyl titanate is 0.3%, the obtained hollow microspheres have the smallest particle size, the biggest BET surface area and show the most efficient degradation of methyl blue dye.