Hydrothermal Synthesis, Characterization And Photocatalytic Properties Of Several Perovskite-type Titanate Materials

Pervoskite-type titanate materials is one of the most widely used materials for electric ceramics because of its great electric characters. Pervoskite-type titanate materials takes an important role in the development of technology and economy.Nowdays people pay more and more attention to energy, environment, health care and other issues closely related with people’s lives, the General Secretary Jiang Zemin proposed the theory of sustainable development, we can see that environmental protection is very important to our own good and future generations will benefit.An important element of environmental protection is waste disposal, the traditional treatment methods include carbon adsorption, isolation and so on. but these methods do not completely eliminate the pollution, it only reduces the extent of contamination. And the pollutants do not completely decompose into harmless substances on human.There still will be harmful. With the development of science and technology, the photocatalytic degradation of pollutants has attracted considerable attention, because the use of sunlight on pollutants is very meaningful. But so far. this means has not been used widely, mainly because the development of efficient photocatalyst is still needed.So far. the study of perovskite-type titanate materials has received much attention of researchers, and the study also has made some achievements. But there are still many problems to be solved, such as the solar spectral range of applications of perovskite-type titanatesalt photocatalyst. the catalytic mechanism is not very clear. So there are still many problems to be solved. We must pay more attention to it and do lots of work.Many methods are applied for preparing the ceramic powders. The hydrothermally prepared powders offer many advantages, such as high degree of crystallinity. well-controlled morphology, high purity and narrow particle size distribution. This method has been widely used in preparation of various powders in recent years.In the present thesis, hydrothermal synthesis is adopted to prepare pervoskite titanate. The main researches achieved are summed up as following:1. SrTiO3particles which had a special morphology were obtained by the hydrothermal synthesis. Purely cubic SrTiO3is obtained with pH=13.00at160℃for24h. The SrTiO3powders were characterized by X-ray diffraction (XRD). scanning electron microscopy (SEM) and transmission electron microscope (TEM). The particles have uniform size distribution and flower-like morphology. The hydrothermal reaction temperature and pH of the system played important roles in the controlling morphology of SrTiO3particles. The photocatalytic activity of SrTiO3with different morphology is also tested.2. Ag-SrTiO3was synthetized with three different methods. The photocatalytic degradation of Rhodamine B had been chosen as a model reaction to evaluate the photocatalytic activities of Ag-SrTiO3. Compared with Pure SrTiO3. Ag loaded SrTiO3showed better photocatalytic performance. Based on the above results, a possible electron-hole transfer mechanism was also assumed. The enhancement of photocatalytic activity is attributed to the formation of a Schottky barrier at the interface between a metal end and semiconductor. The photogenerated electrons in SrTiO3would transfer to Ag. which acts as an electron trap promoting the separation of electrons and holes in SrTiO33. C16H36O4Ti and Ba(CH3COO)2are adopted as starting raw materials to prepare the BaTiO3powders. The product obtained after hydrothermal synthesis has special morphology. The hydrothermal reaction temperature and pH of the system played important roles in the controlling morphology of BaTiO3particles. The process of growth of BaTiO3is also concluded elementarily.