| Due to the outstanding chemical stability, high photocatalytic activity, low-cost and non-toxic, TiO2 is playing an increasingly important role as a environmental material in pollution control, solar energy utilization, etc . However, TiO2 is a wide bandgap semiconductor materials, its photocatalytic activity normally caused only by the ultraviolet part of the solar irradiation, not the visible part of the sunlight ,which make the application to TiO2 inconvenient and costly . Although the study on TiO2 irradiated by the part of visible ligh has made some progress, and a variety of methods to modified TiO2 more or less has increased the utilization effiency of solar energy, according to the outcome of the current study, its photocatalytic and conversional efficiency in visible light are still widely low. In addition, the understanding on the mechanism of various improving performance has not been reunified, there are still controversional.Aiming at the above problems, this study try to use an effective method: making use of metal-ion Pt doped to improve TiO2 ,s performance. which can change the energy band structure of TiO2 , and make the optical absorption threshold of TiO2-doped maximize the visible light areas , that is TiO2-doped can take place electronic transitions in the range of visible light so that it can absorb the visible part of solar energy.And based on density functional theory, using first-principles calculation software CASTEP, un-doped TiO2 and doped TiO2 are simulated. Theoretically the electronic structure and optical properties of the TiO2-doped before and after investigated, and the doped mechanism of TiO2 is carefully analyzed from the energy band structure, density of states, sub-wave density of states, dielectric function, reflectance spectroscopy, absorption spectra and so on, which provided a theoretical basis for the experiment and provide great guiding significance to the experimental preparation of high quality TiO2 material.
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