Iron Silver Doped Nano - Tio <sub> 2 </ Sub> Photocatalytic Properties And The Alternating Electric Field On Its Performance Impact

Today, the pollution of environment is a difficult problem around the world, so it becomes one of the research focuses in every countries. Photocatalytic oxidation method has many advantages such as it has low energy consumption; it can effectively degrade some organics into H₂O, CO₂ and other small molecules, so it can avoid secondary contamination. However, the quantum efficiency of photocatalyst is low; the application of photocatalyst is easy to be influenced by the environment. How to improve the optical absorption ability and the efficiency of photocatalyst has been the research focus.In this thesis, the Fe³⁺doped TiO₂, Ag doped TiO₂, Fe³⁺ and Ag co-doped TiO₂ were prepared by sol-gel method and photoreduction deposition method, whose structure,shape and spectrum characteristics were characterized by XRD, SEM, EDS, FT-IR, XPS and UV-vis. The results showed that the particle size of the powder, being different from that of pure TiO₂, becomed more homogeneous, and the change of size varied with the doped amount and element. The size of Fe³⁺ doped TiO₂ was smaller than that of pure TiO₂, so it could be proved that Fe³⁺ restrained the development of the size of TiO₂. When the ration of Ag was higher than 0.5%, the size of TiO₂ becomed bigger. It showed that when the ration of Ag was excessive, Ag could turn the TiO₂ from anatase to rutile accelerating the increasing of size of TiO₂ particulate. Doping of Fe³⁺ and Ag could change the length of crystal lattice and energy bandwidth, not only the width of infrared spectrum becomed wider, but also the liberate peak value of Ti-O becomed Einstein shift. UV-vis results showed that the absorption sideband of Fe³⁺ and Ag co-doped TiO₂ had red-shift and widen the spectrum absorption range.The photocatalytic activities were evaluated by degradation of mythly orange. At the same time, we investigated the influence of process parameters on the fabrication of doping TiO₂. The results showed that catalyze capability was improved evidently, the optimal doping of Fe³⁺ was 0.1mol%, Ag was 0.7mol%, the optimal co-doping was Fe³⁺ 0.1%Ag0.7%. The photocatalytic effect of co-doped TiO₂ was better than that of single-doped TiO₂. When the degradation of methyl orange was caused by Fe³⁺, Ag co-doped TiO₂, in the condition of alternating electrical field, the reaction velocity was improved. The alternating electric field could not only make the energy band curved, preventing separateing efficiency of electronic and hole, but also prevented the particulate from reuniting. The optimal condition was voltage 25V, frequency 3000kHz, pH=6. Through these experiments and researches, the fitting curves of Fe³⁺, Ag co-doped TiO₂ and alternating electrical field aiding photocatalytic degradation were according to the first order reaction equation of Langmuir-hinshelwood in this thesis.