| With the environment becoming worse day by day, human being has been threatened by water and energy shortage, bad air quality et al. How to achieve sustainable development has been a common goal of every country. Recent years, TiO2has been used in environmental protect due to its high photocatalytic activity, chemical stability, environment friendly, non-toxic and other advantages. But there are two main defects blocking the application of TiO2as a photocatalystic:(1) the band gap of it is3.2eV and only UV-light (which takes up only4%of all the solar radiation) can stimulate it, therefore, the visible light can’t be used;(2) its photo-quantum yield value is very low due to its high recombination rate between photo-generated electrons and holes. So how to development a TiO2sample which can response to visible light and with high photo-quantum yield value has been an important research project in this field. Now there are many methods which can improve the photocatalytic activity of TiO2such as ion doping, noble metal loading, and semiconductor compound, dye sensitization et al. Among them, ion doping attracts more extensive attentions and researches. In this paper, under the guidance of theoretical calculation by our group, the Yb doped TiO2(Yb-TiO2) and Yb/N co-doping TiO2(Yb-N-TiO2) samples were prepared by sol-gel method and microwave chemical method. The structure and morphology of samples were characterized by XRD, TEM and Nano-series Sizer. The spectroscopic properties were characterized by PL, UV-Vis, FT-IR and XPS. The degradation of methyl blue (MB) was investigated to test the photocatalytic activity of samples. The main work and results are as the follows:1. Yb doping TiO2photocatalystsThe Yb-TiO2powders were synthesized by sol-gel method in which Ti(OC4H9)4as precursor, distilled water as the solvent and Yb(NO3)3·6H2O as Yb source. The influences of Yb doping content, sintered temperature and pH value on the properties of Yb-TiO2samples were researched. The results show that the Yb-TiO2samples are a mixed phases of anatase and rutile. Compared to P25, Yb doping expands the absorption edge of them about18nm and decreases the recombination rate of photo-generated electrons and holes. The excellent preparation condition is as the following:reaction temperature60℃, sintered temperature650℃, Yb doping concentration:Yb:Ti=0.015and pH value=2.5.2. Yb/N codoping TiO2photocatalystsThe Yb-N-TiO2powders were prepared by microwave chemical method and sol-gel method. The influences of Yb doping content and sintered temperature on the properties of Yb-N-TiO2samples were researched. The results show that Yb/N co-doping expands the absorption edge of them about80nm, decreases the recombination rate of photo-generated electron-hole pairs and inhibits phase change. The excellent preparation condition is as the following:reaction temperature60℃, sintered temperature650℃, Yb doping concentration:Yb:TiO2=0.005, m (H2NCONH2)=10g and pH value=1.5.The novelties of the work are mainly focused on the following aspects:(1) we chose Yb as the doping ion and deeply researched the influences of Yb doping and Yb/N co-doping on the properties of TiO2. At the same time, we researched stability of the as-prepared samples. At present, there are only two articles about Yb-doping and Yb-N-codoping TiO2both at home and abroad.(2) We choose Yb and Yb/N doping TiO2mainly due to the theory guidance of our group. Such recombination of theoretic and experimental work can effectively overcome the blindness and repeatability of the research. |
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