Effect of Preparation Conditions on the Size of TiO_2 Powders Prepared with the Sol-emulsion-gel Method

Titanium dioxide photocatalyst powders were prepared with the sol-emulsion-gel method. The influence factors, such as surfactant concentration, pH values of solution, water content and calcination temperature, on the size and distribution of TiO2 nanoparticles were investigated. The results show that TiO2 nanoparticles are very small when the concentration of the surfactant reaches the critical concentration of 9.20×10-4 mol/L and a good distribution can be obtained. Nucleophilic reaction will occur in the basic solution for the Ti(OC4H9)4, the TiO2 nanoparticles with the smallest size will be obtained when the pH value is 8.4. The size of TiO2 nanoparticles will decrease rapidly with the increasing of water and it will reach a steady constant when the water content is 0.5mol/L. The crystallinity of TiO2 nanoparticles can be improved by calcination, which makes the amorphous phase transform to anatase and rutile. The shape of the particles can be noticed as: Formed sphere→Rod→Sphere→Distorted sphere.