| TiO2 known as a represented photocatalytic environmental material has been extensively studied. Photocatalytic degradation of organics to protect environment become the most active research directions in the scientific community. TiO2 as a photocatalyst with good performance is mainly reflected in its unique chemical and thermal stability, high efficiency, non-toxic, low cost. The photocatalytic efficiency of titania is strongly dependent on the crystalline structure morphology and size of the partieles. Conventionally, titania catalysts are synthesized by sol-gel method followed by calcinations at elevated temperatures. And the heat treatment step is accompanied by sintering, grain size growth, and loss of surface area on catalyst partieles that are known to reduce catalytic activities. Thus, the lack of high catalytic activity hampers its industrial application. In this paper, rutile TiO2 powder, mixed crystal TiO2 powder and mixed crystal TiO2 film were synthesized via applying hydrothermal method at low temperature. And crystal phase, structure and photocatalytic property of TiO2 were researched. The detailed works are as follow:Powder TiO2 was synthesized in low temperature aqueous medium by oxidation and hydrolysis of titanium trichloride (TiCl3) with NaNO3 as oxidant. The crystal phase, structure and photoabsorbed function of TiO2 were characterized by XRD, TEM and UV-Vis.The result showed that powder sample was rod-shaped rutile TiO2. And the photocatalytic activity was evaluated by photocatalytic degradation of methylene blue with 300W iodine-tungsten lamp as light source. Prepared TiO2 had the highest photocatalytic activity when the crystallization temperature was 200℃and crystallization time was 2h. An excellent methylene blue degradation rate(53.66%) was achieved after reacting for 6h. The rutile titania nanoparticles is superior to P-25(39.32%).Rutile TiO2, anatase TiO2, and two-phase discretional mixed crystal TiO2 were synthesized successfully in low temperature aqueous medium by oxidation and hydrolysis of titanium trichloride (TiCl3) with NaNO3 as oxidant and Na2SiO3 as additive. Sample TiO2 were characterized. The research showed that different mixed crystal ratio of TiO2 were prepared via adjusting the amount of Na2SiO3. And SiO32- can adjust crystal phase of TiO2 because it can influence the process hydrolyzing of TiO2. The photocatalytic activity was evaluated by photocatalytic degradation of methylene blue. Mixed crystal TiO2 have a higher degradation ability compared to purely TiO2. The mixed crystal TiO2 had the highest photocatalytic activity when anatase percentage was 62.78%. The degradation rate was 86.09% after reacting for 6h. It is superior to rutile TiO2 photocatalyst which was synthesized.Uniform, stable and dense TiO2 film was synthesized on the double face of ordinary glass slide using hydro-thermal method at low temperature with TiCl3 as titanium-source, NaNO3 as oxidant and Na2SiO3 as additive. The results of XRD showed that the TiO2 film was mixed crystal of rutile and brookite. Mixed crystal TiO2 film has a strong UV absorption properties in the wavelength range of 190～380 nm by UV-Vis diffuse reflectance spectroscopy. Methylene blue degradation was used as a probe reaction to evaluate the photocatalytic activity of TiO2 film. After reacting for 12h the degradation rate achieved 84.87%, and the degradation rate held stable after this membrane was used 4 times. The fluctuation of photocatalytic degradation rate is less than 1% when mixed crystal TiO2 film was used repeatedly. And the shed phenomenon of mixed crystal TiO2 film was not found. It proved that glass slide combined with mixed crystal TiO2 film strongly. |
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