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The environment pollution and energy shortage was a really important issue we must be faced in nowadays. The nano titanium dioxide attracted more attention as the excellent performance of high photocatalytic activity, stability of the physical and chemical properties, non-toxic and low-cost, the study for titanium dioxide semiconductor photocatalytic materials was be named as the "Sunshine Project","light clean revolution" by some scientists. The superoxide radicals and hydroxyl radicals will be formed in nano-titanium dioxide by the electrons (e-) and holes (h+) which excitation through photon, thus strong oxidation products could oxidative and decomposition the pollutants completely and will not cause secondary pollution. However, cause the narrow spectral response range, low quantum conversion rate, low utilization rate of light, difficult recovery in actual degradation process, in nano-titanium dioxide, the application was limited in practice. So, how to improve the spectral bandwidth and the quantum efficiency of titanium dioxide in the visible region became a hot spot in research. The methods such as control polymorphs, noble metal deposition, ion doping, dye sensitization, binary semiconductor composite was be used the most commonly.In this paper, nano-titanium dioxide photocatalytic mechanism was introduced detailedly, the nano-composite photocatalyst--Fe3+-TiO2, Fe3+metal ions doped, compound by the method of Sol-Gel, were characterized by XRD, SEM, TEM, TG-DTA and UV-Vis-NIR characterization methods for its impact factors and catalytic activity in preparation process.A series of experiments and research was be done in the following aspects in this paper:(1) Metal ions Fe3+doping. The Sol-Gel was be used, tetrabutyl titanate as precursor, iron nitrate as iron source, anhydrous ethanol as a solvent, the PH value in reaction process was controled by concentrated nitric acid, the pure nano titanium dioxide powder and titanium dioxide nano-composite photocatalyst doped with different amounts of Fe3+was prepared. The effect of the factors such as reaction temperature, stirring speed, Fe3+concentration, calcination temperature and time for the photocatalytic properties of the sample was discussed. The results showed that: the better morphology of sample was prepared, and the light absorption band appears red shift obviously, the bandwidth is increased, when the PH was3, stirred at room temperature, constant temperature drying at35℃, sintering at650℃, the molar mass ratio of Fe3+and TiO2was5%, that can making the TiO2play a good degradation under visible light irradiation, thereby improving the photocatalytic efficiency.(2) Precious metal Ag doping. The Ag-TiO2composite photocatalyst was prepared using the same way. The photocatalytic properties of the Fe3+-Ti02and Ag-TiO2was compared through a variety of characterization methods. The results showed that:the absorption properties of Ag nano-titanium dioxide photocatalyst doped was better than the Fe3+doped when sintered at600℃in the same reaction process:the PH was3, stirred at the room temperature, drying at the constant temperature35℃.(3) The effect of PH value for the nano-composite photocatalyst performance of Fe3+-TiO2. The nano-particles Fe3+-TiO2were prepared in type of acidic and alkaline environments in different of PH, controled by concentrated nitric acid and aqueous ammonia. The morphology, phase, the light absorption properties was observed by a variety of test equipment. The results showed that:it could be got the better morphology, stronger absorption properties of the light catalyst sample in the acidic environment when prepared at the room temperature, drying at the constant temperature35℃, stirred at the different temperatures.
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