Studies On The Controlled Synthesis, Growth Mechanisms And Properties Of Transition-metal Oxides Nanomaterials/Nanocomposite

The nanomaterials exhibit a lot of unique properties, such as quantum size effect, small-size effect, surface effect and macroscopic quantum tunnaling effect and have potential appications in catalysis, ligt filtering, ligt absorbance, medicine, magnetic mediam and new materials. TiO2 nanomaterials have intensively attention because of the outstanding properties including small diametre, large specific surface, photocatalysis, good UV absortance, good thermal transmition, and well-dispersion and stable suspension. Three major methods such as hydrothermal method, Rheological Phase Reaction and wet chemal method have been employed. The hydrothermal method employed in the present work has one-hundred year history, and then there are plenty of theories and experiments about the method. The method can supply a special enviorement, which can hardly abtain in normal temperature and pressure. It is easy to gain nanocrystals, which have the natues such as well-crystalline, uniform diametre and little conglomeration. and the start materials is cheap. Furthermore, the chemical component, grain size of the the as-prepared product can be controlled with lower cost.In the present work, the preparations, morphologies, crystal structures, growth mechanisms and photocatalytic activities of TiO2 synthesized using TiCl3 as the start material were dicussed in details. It could be helpful to the applications and further study of TiO2 nanomaterials. This dissertation consists of seven chapters in total article. Chapter one is the an introduction, in which the origin and supporter of the project, significance and the major author's work are introduced briefly.The development and present research situation in the world in the areas are reviewed and the trend of the further development is also discussed, such as catalytic materials, TiO2 catalytic materials.The method of the preparation of nanomaterials, the theories of the hydrothermal method and the applications in nanomaterials are discussed in chapter two.The synthesis of single-crystal rutile TiO2 nanorods via one-step solution route at low temperature is discussed in chapter three. It is found that the product is well crystalline TiO2 without further sintering. The growth mechanism of the nanorods reveals that the growth direction is parallel to the c-axis. Further photocatalytic activities of rods and TiO2/MnO2 exhibit higher efficiency even than that of P25 in visible light.Different crystal type, properties and morphologies of TiO2 were synthesized by adjusting the solution and the pH values. The influnced factors are discussed in chapter 4. In the water and ethanol mixed solution, the flower-liked microstrctures were synthesized by adjusting the concentration of the HCl.The chapter 5 investigates the hydrolysis of TiCl3 at alkalescent environment. The results display all the products are anatase TiO2 and the specific surfaces area are abviously improved than that of nanorods and microstructures. The rheological phase reaction method is introduced to synthesis of TiO2 nanomaterials, and it is a novel thought of preparation of photocatalytic materials.The praparation of the carbon nanotube/MnO2 and Cnts/TiO2 are introduced in chapter6. The electrochemical properties shows the nanocomposites enhance the capability and photocatalytic ability than the original carbon nanotubes or TiO2 nanomaterials, even than that of P25 in visible light. But there are a lot of defects such as imcomplete degradation of organic compound, and it is a lot of work to do in the future.