|关键词||二氧化钛 水热法 介孔结构 异面结 混晶结构 光催化|
Titanium dioxide (TiO2) has attracted much attention because of its specific properties: photocatalytic activity, photovoltaic effects, long-term stability, nontoxicity, and low cost. The photochemical reactivity, physicochemical properties and application for TiO2 strongly depends upon the crystal structure, morphology, size and microstructure of the particles. Therefore, it is of great important to develop an effective method to synthesize TiO2 with controllable phases and morphologies and it has been an important research focus in the field of materials and photocatalysis. However, its wide band gap reduces the utilization efficiency of sunlight; it enhances the recombination of photogenerated carriers and lowers quantum efficiency, thus limiting the application of it in life. As it can extend the scope of TiO2 spectrum and restrain the recombination of photogenerated electron-hole pairs to result in a drastic improvement of photocatalytic activity by means of decorating the TiO2 with such as metal deposition, ion doping and coupled semiconductor et al, it will pay much on the preparation technology and additional decorative materials. Herein we prepare TiO2 samples without decoration by a simple one-pot hydrothermal synthesis taking Titanium (IV) bis (ammonium lactate) dihydroxide as the precursor, which has great photocatalytic activity due to such as controllable large specific surface area and mixed crystal structure. Our main work is as follows: (1) We prepare adjustable micro/meso-porous anatase TiO2 with large specific surface area by a one-pot template-free synthesis using HCl. The size of pores can be adjusted by the reaction time and the photocatalytic activity changes as the porous size. We study the different degradation rates of 2,4-Dichloropheno using TiO2 samples with different porous sizes upon UV-light irradiation in one hour and compare them to Degussa P25. The results show that TiO2 samples prepared with 72 h can degrade the 2,4-Dichloropheno more quickly than P25, which the former and later degradation rates are 89.8% and 74.3, respectively. (2) A new kind of crystallographic plane junctions (CPJs) between (101) and (200) facets of anatase TiO2 has been fabricated by a simple one-pot hydrothermal method by controlling the reaction time using HF. The CPJs are featured with mismatch of as large as 84%. We study the photocatalytic water splitting upon UV-light irradiation to produce H2 using anatase TiO2 samples with CPJs or not. It demonstrates that photocatalytic H2 production with TiO2 samples containing CPJs is 4 time higher than that not containing CPJs, which is even higher compared to the H2 amount produced by P25. (3) The mixed crystal structure of anatase and rutile TiO2 samples are synthesized by adjusting the pH of reaction solution using HNO3 and NH3?H2O. We study the relation between the mass ratio of anatase to rutile and the particle size, specific surface area and photocatalytic activity of prepared TiO2 samples. The results indicate that the photocatalytic degradation efficency of methyl orange will higher than that of anatse TiO2 and rutile TiO2 samples when the mass ratio of anatase to rutile is in a specific range.
|张颖. 纳米TiO2的一步水热法可控制备及光催化性能研究[D]. 北京. 中国科学院大学,2014.|
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