Research On Synthesis And Photocatalytic Activity Of Lanthanum-Cerium Co-doped Nano-Titanium Dioxide

Compared with conventional materials, nano-materials have many singular features and new special features because of their small size effect, interface effect and macroscopic quantum tunnel effect on the optical, electrical, thermal, magnetic and other physical properties and chemical properties. Oxide semiconductor nano-catalysts heterogeneous photocatalysis is an ideal environment for pollution control technology, has become the most active international research areas in recent years. Nano-TiO₂ has been most commonly used with the characteristics of strong oxidizing ability, non-toxic harmless, the higher the degradation efficiency, low cost and no secondary pollution. TiO₂ nanotubes have a larger surface area than nanopowder and thin films, this surface area of nanotubes provides more reaction active sites so that degradation of material to be more conducive to the adsorption and reaction; tubular structure provids a good channel for electronic migration and interface charge transfer. Using the unique 4f electronic structure of rare earth elements, rare earth doped TiO₂ is commonly used to improve the photocatalytic activity of TiO₂. Looking at the current large number of rare earth doped TiO₂ photocatalytic studies, most are single rare earth doped, both rare earth elements and transition metals or non-metallic elements doped, mixed rare earth doped TiO₂ is minimal.Sol-gel method was used to prepare lanthanum cerium co-doped TiO₂ nanoparticles in this paper. To synthesis lanthanum cerium co-doped TiO₂ nanotubes by microwave based on the nano-powder precursor, while compared to the photocatalytic properties between them. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray fluorescence spectrometry (XRF) are used to characterize morphology, structure and composition of samples, and analyze its formation mechanism. To analyze the degradation process on preparation and photocatalytic degradation of organic matter by methyl orange as photocatalytic reaction model compounds. The results showed that:1. The TiO₂ nanoparticles which are prepared by sol-gel is evenly, and the diameter is between 10-20nm. The dopant have a great impact on the nanoparticles size, the doped nanoparticles size is smaller than the undoped, which illustrates that the growth of nanocrystals is restrained. Rare earth ion doped can restrain the phase transition, which can raise the TiO₂ transition temperature from anatase to rutile.2. To TiO₂ nanoparticles as the precursor, the relatively complete morphology of TiO₂ nanotubes can be prepared by microwave. TiO₂ nanotubes are open, hollow tube, almost the same diameter by observed in the electron microscope, the outer diameter of La-Ce co-doped TiO₂ nanotubes is 10-15nm, the inner diameter is 4-8nm, and the length is about 50-80nm.3. To methyl orange as target degradation, the nanopowder and nanotube are studied about photocatalytic by the 15W UV light irradiation at 150min, the result show that La-Ce co-doped improves the photocatalytic activity of TiO₂ nanoparticles and nanotubes. The high activity is due to the strong absorption of UV-visible range, the formation of oxygen hole, the enhanced adsorption capacity and so on.