| Titanium oxide (TiO2), as one of obbligato transition semiconducting material, has been attracted much more attention by researchers due to its novel structures and superior properties. TiO2 has been widely used in many fields including catalytic chemistry, biological chemistry, medical science, et al, because of cheap, easy acceptance, non-toxicity, excellent photo-stability. However, the large bandgap (anatase?3.2eV) led some weaknesses such as high-energy radial excitation and rapid combination of photoreduced charge and limited its further applications. Many efforts have been attempted to enhance the charge separation efficiency and the absorption under the irradiation of UV light by tuning of the band gap of TiO2 by Ag and rare earth elements doped TiO2 to increase photocatalytic activity. So our work is to prepare of TiO2 doped by rare earth element and Ag to improve their photocatalytic performance. Our work is summarized as follows:(1) In this paper, TiO2 nanoparticle doped with varying content of Ce was prepared by a sol-gel method using Ti(OC4H9)4 and C2H5OH. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption isotherm (BET), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The photocatalytic activity of Ce-doped TiO2 microspheres was evaluated by photodegradation of Rhodamine B (Rh B) and methylene blue (MB) under ultraviolet light irradiation. The results showed that the doping content of Ce greatly inhibited the increase of crystallite size. The specific surface areas of the samples increase from 72.3 m2·g-1 to 120.2 m2·g-1. All the Ce-doped Ti92 microsphere samples displayed higher photocatalytic activity than that of undoped TiO2. Furthermore, research also exhibited that the as-prepared 0.5%Ce-doped TiO2 nanoparticles possess optimal photocatalytic activity. It can be seen that the degradation rate of Rh B and MB reaches 93.7% and 86.4% after 180 min, respectively.(2) TiO2 nanoparticle doped with varying annealing temperature was prepared by a sol-gel method using Ti(OC4H9)4 as titanium source. The synthesis of Ce/TiO2 powders were confirmed by X-ray diffraction (XRD)?Field-emission scanning electron microscopy (FE-SEM)?N2 adsorption-desorption isotherm (BET) and transmission electron microscopy (TEM). The photocatalytic activity of Ce-doped TiO2 microspheres was investigated at different annealing temperatures by measuring the degradation rate of Rhodamine B (Rh B) under ultraviolet light irradiation. The results showed that the doping of Ce greatly inhibited the transform from anatase to rutile under a certain temperature. The specific surface areas and micropore volume of the samples increase. All the Ce-doped TiO2 microsphere samples showed higher photocatalytic activity than that of the commercial TiO2 (P25). The optimum reaction temperature is 650? and the degradation rate for Rh B reaches 95% after 180 min.(3) Ag/TiO2 catalyst was prepared by the sol-gel method. The nanoparticles were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption isotherm (BET), and transmission electron microscopy (TEM). Degradation of methylene blue (MB) was studied at different doping contents and different calcination temperatures. The results showed that the specific surface areas of the samples increase and the transition from anatase to rutile were greatly inhibited when the calcinated temperatures was 800?. Also the photocatalytic activity was found to increase after Ag was doped. When the calcinated temperature was 500? and 1% Ag doped TiO2 nanoparticles were irradiated under ultraviolet light, the degradation rate of MB reached 90% after 180 min.(4) In order to explore the relationship between the content of different doping elements, different calcination temperature and the rate of degradation, Ce-Ag doped TiO2 materials were synthesized through a sol-gel method. These catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption isotherm (BET), and transmission electron microscopy (TEM). The obtained materials maintained large surface area of 123.3 m2·g-1 after co-doped TiO2, Furthermore, the samples were greatly inhibited the transform from anatase to rutile.When the calcinated temperature is 500?, the degradation rate of MB reaches 92% after 180 min under ultraviolet light irradiation, the photocatalytic activity of co-doped TiO2 nanoparticles were obviously higher than that of the pure and single doped samples, and reached the optimum at Ce and Ag contents of 1.5 mol% and 0.5 mol%. |
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