The Electronic Structure And Optical Properties Of Nanometer TiO₂ Doped With Transition Metals

Titanium dioxide nano thin films have attracted considerable attention in recent years, due to their unique photophysical properties and photocatalytic degradation activity of organic coumpounds. In present work, the properties of TiO₂ have been studied both in theory and experiment. Three phase of titanium dioxide have been simulated by ab initio band calculations based on the density functional theory with the pseudopotential metod. The electronic structures, geometry and optical properties of dioxide (TiO₂) have been analyzed systemly. For rutile and anatase, the calculated band structures, equilibrium and lattice constants are in good agreement with other recent calculations and with experiment data. The results on the ground-state properties of brookite are reported. The optical properties of these phases are also calculated using the band-structure results and compared with the available measurements. Our calculations show subtle differences in the optical properties of these three phase. By the simulation, some useful parameters, such as geometry and dietetic parameters, have been presented. To improve the photocatalytic activity of TiO₂, TiO₂ doped with 3d transition metals have been studied widely. In this work, the electronic structures of titanium dioxide (TiO₂) doped with 3d transition metals (V, Cr, Mn and Fe) have been analyzed by ab ignition band calculations with the full-potential linearized-augmented-plane-wave method. Based on the results of computation, we show that the t2g state of the dopant, which is localized, plays a significant role in the photoresponse of TiO₂ under visible light irradiantion. We also prepare and test some samples of TiO₂ doped with Fe3+. The previous predictions are confirmed by our experiment. Titanium dioxide nano thin films were prepared by sol-gel and tested by UV-vis spectrometer. Absorption curve of TiO₂ doped with transition metals were ploted and optical band gaps were presented. UV-Vis measurements showed that the red-shifting occurred when TiO2 doped with Fe3+. On the contrary, blue-shifting was found for TiO2 doped with Ag+.