【作者】 张荷美；

【导师】 宋秀芹；

【作者基本信息】 河北师范大学 ， 无机化学， 2010， 硕士

【摘要】 半导体TiO₂光催化剂在空气净化、污水处理、自洁净玻璃、防雾和抗菌等领域具有广阔的应用前景。目前,TiO₂光催化剂还存在光催化活性较低以及对太阳光的利用率很低等难题。近年来,TiO₂光催化剂的改性技术得到了迅速发展,包括半导体复合、过渡金属离子掺杂、非金属掺杂、贵金属沉积、表面光敏化等方法。本论文针对纳米TiO₂的缺点,重点研究纳米TiO₂与其它半导体的复合,利用表面吸附层反应成功地将纳米TiO₂与ZnO和CuO复合,制备了微/纳米结构的ZnO/TiO₂和CuO/TiO₂复合物,并对其光催化活性进行了研究。主要内容如下:第一,综述了半导体光催化剂TiO₂的光催化反应机理,以及TiO₂光催化剂的研究进展及其应用。第二,为了使得光生电子和光生空穴的寿命延长,提高TiO₂的光催化活性,将其与禁带宽度相近的ZnO复合。以Zn（Ac）2和NaOH为原料,采用湿法合成微米尺寸的花状和棒状的ZnO微晶,将其作为纳米TiO₂的载体,利用表面吸附层反应成功地制备了微/纳米结构的ZnO/TiO₂复合物。第三,为了拓宽TiO₂光催化剂的光响应范围,并且能更好的分离e^--h⁺对,提高光催化量子产率,将其与禁带宽度较窄的CuO复合。以CuSO₄·5H₂O、NaOH和C₆H₁₂O₆为原料,在常压下70℃时,不加任何添加剂的情况下,制备微米尺寸的球状和立方块状Cu₂O微晶,经热处理后得球状和立方块状CuO,将其作为纳米TiO₂的载体,利用表面吸附层反应成功地制备了微/纳米结构的CuO/TiO₂复合物。第四,通过光催化实验,验证复合光催化剂的光催化活性。以甲基橙为模拟废水,将微/纳米结构的ZnO/TiO₂和CuO/TiO₂复合物与甲基橙溶液混合均匀,分别经高压汞灯或日光灯照射反应,研究其光催化性能。实验结果得出了花状和棒状ZnO/TiO₂复合催化剂分别是摩尔比为1:3和1:1的光催化活性最好;球状和立方块状CuO/TiO₂的复合催化剂均为复合比例为2:1的光催化性能最好。并用催化活性最好的催化剂研究不同浓度的催化剂、不同甲基橙初始浓度对光催化效果的影响。更多还原

【Abstract】 As a semiconductor photocatalyst, considerable attention has been focused on TiO₂ owing to its unique properties and promising applications, such as air purification, waste water treatment, self-cleanness, mist prevention, bacillus resistance and so on. However, it is still a great challenge to overcome the problems of low photocatalytic activity and low utilization of sunlight. In recent years, there is a rapid development of the improvement of TiO₂ photocatalyst, including the compositing of semiconductor, the doping of the transition metal ions and the non-metallic ions, the depositing of the precious metals and the sensitizing of TiO₂ surface.In this paper, have been focused on the combination of nanosized TiO₂ and other semiconductors materials based on its disadvantages. Micro/nano-structures ZnO/TiO₂ and CuO/TiO₂ composites photocatalyst were prepared by the hydrolyzation method in the surface adsorption layer of the micron dimentional ZnO and CuO. And the photocatalytic activity of the composites was given as a detailed research. The main contents are as follows:Firstly, the reaction mechanisms, the research progresses and the applications of TiO₂ photocatalysts were reviewed.Secondly, in order to keep light electron and hole prolonging and improve the photocatalytic activity, TiO₂ was composited with ZnO which has the similar band-gap. Zn（Ac）₂ and NaOH are used without further purification, the micron dimentional flower-shape and rod-shape ZnO microcrystallines were prepared through a facile wet synthesis. Additionally, the micro/nano ZnO/TiO₂ composite photocatalyst was successfully synthesized by the surface adsorption layer reaction with these microcrystallines as the carriers.Thirdly, TiO₂ was composited with CuO which has the narrower band-gap to broaden the light response range, separate electron-hole pairs, and improve the photocatalytic activity. In a typical preparation, CuSO₄·5H₂O, NaOH, and C₆H₁₂O₆ were all commercially available and used without further purification, the micron dimentional spherical and cubic Cu2O microcrystalline were prepared at 70℃and atmospheric pressure without any surfactants. After heat treatment, the spherical and cubic CuO were obtained. Then with CuO as the carrier of nanometer TiO₂, the micro/nano CuO/TiO₂ composite was successfully prepared by the surface adsorptive layer reaction.Fourthly, experiments were carried out to test the photocatalytic activity of the composite photocatalyst. Methyl orange was selected as a representative dye pollutant of industrial wastewaters. The photoreactor was designed with a high-pressure mercury lamp or fluorescent irradiation, and the abtained micro/nano ZnO/TiO₂ and CuO/TiO₂ was added as the photocatalyst into Methyl orange. The experimental results indicated that the flower-shape and rod-shape ZnO/TiO₂ composites showed the best photocatalytic activity with the mole ratio of ZnO:TiO₂ 3 to 1 and 1 to 1. However, the spherical and cubic of CuO/TiO₂ composites gave the best light catalytic performance with the both mole ratio of CuO:TiO₂ 2 to 1. The effects of different concentrations of catalysts and different initial concentrations of methyl orange on photocatalytic activity were also studied using the catalysts which had the best catalytic activity.更多还原