Preparation And Properties Study Of Nano Porous TiO₂ Hollow Spheres

In recent decades, nanostructured materials have attracted much attention due to their special structure and excellent properties in optics, electrics, magnetics, chemistry, etc. Particularly, nanostructured titanium dioxide (TiO2) has been applied widely in many fields, such as chemical industry, electronic industry, environmental protection, cosmetics industry, medical science and so on. In order to improve the materials performance, nanostructured TiO2 with various morphologies, including particles, tubes, rods and spheres, has been investigated and fabricated successfully. Hollow structure material, as a newfashioned kind of materials, exhibits broad application prospect, because of its higher specific surface area, lower density, greater delivering ability, better permeation and stronger light-harvesting capacity compared to solid ones. Accordingly, the synthesis of hollow structure metal oxide has been the researchers'new subject. Up to now, many kinds of TiO2 hollow spheres were fabricated by different methods. However, there are still some problems in the technological process and product quality. In this paper, nano TiO2 hollow spheres material was prepared through a hydrothermal method, and the structure, morphology, properties of the products were characterized and researched. The main tasks are as follows:1. Nano TiO2 hollow spheres were obtained successfully in the ethanol solvothermal medium using tetrabutyl titanate and ammonium bicarbonate as reactants. XRD, SEM, TEM and BET were employed to characterize the as-synthesized TiO2 hollow spheres. The results showed that the products are anatase phase and has uniform morphology and good dispersion with average diameter of 100 nm and shell thickness of 20 nm.2. The effect of reaction time, temperature, and assistant agent on the phase and structure of the product were studied. A bubble-assist Ostwald ripening mechanism was proposed to explain the formation mechanism of porous TiO2 hollow spheres. This approach employs bubbles generated in situ as template combined with Ostwald ripening process, which is considered as a green and simple route to prepare hollow spheres.3. The optical property, photocatalysis activity, adsorbability and gas sensitivity of the products were researched, expecting to apply them in related fields. The results showed that the TiO2 hollow sphere samples exhibit very intense adsorption for organic dyestuff, and have a good behavior in gas sensitivity for methanal.