The Doped Of Nano-photocatalyst And The Study Of Its Character

Because of high activity, low prices and stable of TiO2 photocatalytic material, it has become more valuable materials in the 21st century. It can be applicated in the purification, water treatment and other aspects in our environment. But the band gap of titanium dioxide is about 3.2eV, this result the practical application of it has been greatly restricted. In addition, titanium dioxide could produce electron and hole by excitate of light, but the recombination rate of electron and hole are very high which decreased the photocatalytic efficiency to pollutants (the low rate of quantum yield). Many methods can improve the photocatalytic efficiency such as semiconductor compound, dye sensitization, noble metal deposition, ion doping and double element doping, thus, we synthesized different doped titanium dioxide photocatalyst by different methods in our study. At the same time, we evaluate the physical and chemical properties of doping titanium dioxide. The specific contents and results are as follows:(1) pure titanium dioxide and doped titanium dioxide are synthesis by Hydrolysis of titanium alkoxide and sol-gel method; Moreover, we also study the relation between the amount of water and the gel formation time. The amount of water on the titanium alkoxide solution and the formation of the gel were study by orthogonal experimental method. The optimal ratio of nano-TiO2 photocatalyst was determined by sol-gel synthesis, and the result is that Mn-butyl titanate:Methanol:Macetic acid:Mdeionized water= 1:18:2:3.5 (molar ratio). Meanwhile, the hydrolysis of butyl titanate was determined by the same method.(2) A series of Nd and I doped TiO2 photocatalyst were synthesized by the hydrolysis of titanium alkoxide. The characteristics of neodymium and iodine doped TiO2 were evaluated by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra, scanning electronic microscope (SEM) and Energy Dispersive X-Ray Spectroscop-y (EDS). In the synthesis process, Nd:I:TiO2 with different doping content (molar ratios) calcined at different temperature was designed. The photocatalysis activity was evaluated by methylene blue (MB) and bovine serum albumin (BSA), and the mold resistance was evaluated by colibacillus (E.coli) and Staphylococcus aureus (S.aureu- s). The results show that Nd doped TiO2 can prevent the growth of it, and has intense absorption at 528,587,683,750,808, and 881 nm, this phenomenon mainly due to the 4f electron structure of Nd. I doping can extended the response vastly of TiO2 in visible region, Nd and I co-doped TiO2 can extend the band of TiO2 to 2.82 eV (MNd:MI:MTi=5:10:100 (Molar ratio)). MNd:MI:MTi=5:10:100 (molar ratio) has highest photocatalysis activity by photocatalytic degrade MB and BSA in 300 W tungsten, and the degradation rate of MB (3.86×10-2 min-1) is about 17 times compared to pure TiO2 (2.28×10-3 min-1). The mold resistance of optimum photo-catalyst could kill E.coli and S.aureus through damaging their outer membrane (even deteriorated completely) by their radiation of light.(3) A series of Nd and F doped TiO2 photocatalyst were synthesized by the sol-gel method. The characteristics of neodymium and fluorine doped TiO2 were evaluated by the same method with the above (2). In the synthesis process, Nd:F:TiO2 with different doping content (molar ratios) calcined at different temperature was designed. The photocatalysis activity was investigated by methylene blue (MB) under ultraviolet and visible light, respectively. The results show that Nd doping has the same effect with the above (2). F doping can makes crystal growth and crystallization complete of TiO2, and it also can make the band gap red shift of TiO2. TiF5Nd0.5 has the maximum redshift, and it band gap was calculated about 2.91 eV. In the UV-irradiation, TiF5Ndo.5 has the highest photocatalytic degradation rate to MB, and it degradation reaction rate constant was about 1.76 times than pure TiO2; in the visible light motivate, TiF5Nd0.5 also has the highest photocatalytic degradation rate to MB, and it degradation reaction rate constant was about 1.45 times than pure TiO2.