Study On Sol-gel Preparation And Photocatalytic Activity Of TiO₂

Nanometer TiO₂ as a catalyst has many advantages such as safety, good stability, high efficiency, low cost and no secondary pollution, so it has huge potential value in the environmental pollution control and other fields.TiO₂ powders, however, has some shortcomings, for example, difficult to be separated, difficult to be recycled, high cost of post-processing, and so on. Compared with Ti O₂ powders, TiO₂ films is reusable, easy to be recycled, thus it has a wider development application prospect. The TiO₂ thin films have been prepared by sol-gel method, and photocatalytic properties of TiO₂ thin films have been studied. The main research contents and conclusions can be summarized as follows:1. The titanium sol is prepared used the sol-gel method by isopropyl titanate as s titanium source and HNO3 as inhibitors, and TiO₂ thin films are prepared by the method of dip coating. The properties of TiO₂ thin films have been characterized by XRD, SEM and spectrophotometer. The important preparation parameters during TiO₂ thin films preparation, including materials ratio, temperature, coating layer, the injected water speed, the pH of the solution, the using of polymer compounds, how to effect on thin films’ structure and photocatalytic activity has been investigated. The results show that TiO₂ thin films are prepared under the conditions of acidic solution, isopropyl titanate and deionized water molar ratio of 1∶8, the volume ratio of different materials: isopropyl titanate∶anhydrous ethanol∶nitric acid∶deionized water=2∶6∶0.5∶1, added deionized water slowly, coating 3 times, and calcination temperature 450°C,which have good performance and smooth surface.2. The photocatalytic properties of TiO₂ film has been investigated using the rhodamine B solution. Some important factors affecting the photocatalytic performance of TiO₂ have been studied, and compared the photocatalytic performance of TiO₂ films to TiO₂ powder. The conclusions are as follows: Calcination temperature and the coating number can improve the photocatalytic efficiency and there is a optimal value; different substrates can also influence the photocatalytic activity. Compared with different substrate materials, the photocatalytic performance of TiO₂ film choosing one side frosted glass slide as substrate is best; doping is one of important means to modify TiO₂ thin film, both a small amount of metal doping and co-doping can improve the photocatalytic performance, but the doping or co-doping amount too much, is not conducive to improvement of photocatalytic activity. In addition to the factors during TiO₂ films preparation, catalyst dosage, the concentration and volume of the pollutants, illumination time and light distance are also cannot be ignored. Increasing catalyst dosage and extending illumination time both can improve the photocatalytic performance. While the higher the pollutant concentration, the greater the volume, and the bigger the light distance, the worse the photocatalytic properties.3. Compared with the Ti O₂ film, TiO₂ tablet is prepared, and its performance is simply investigated. The conclusions are as follows: The preparation of TiO₂ tablet is simple, photocatalytic performance is good, and it can be recycled. Doping cannot always improve TiO₂ photocatalytic activity, a small amount of doping can improve the photocatalytic performance, but with the increasing of doping amount the photocatalytic activity will reduce. Although TiO₂ tablet also has the phenomenon that a small amount of particles fall off from tablet, but it gives us a new way to use TiO₂ and improve its properties.