【作者】 刘丽丽；

【导师】 陈守刚；

【作者基本信息】 中国海洋大学 ， 材料学， 2011， 硕士

【摘要】 半导体TiO₂禁带宽度为3.2 eV,只能吸收紫外光才能产生活性,而紫外光仅占太阳光的5%,这样只有波长等于或小于387 nm的紫外光才能激发TiO₂产生导带电子和价带空穴对而引发光催化反应。为了有效利用太阳光,对TiO₂进行掺杂改性来扩展其光响应范围从而提高其在可见光区的光催化活性是目前TiO₂光催化领域很重要研究课题之一。克服这一局限性,本文侧重于将TiO₂进行改性,尝试不同的掺杂方式对其改性的影响,并抑制光生电子–空穴对的复合,寻求一个最佳模式来提高TiO₂在可见光区的光催化效率,达到充分利用太阳光的目的。研究内容及成果如下:1、非补偿性掺杂:对于n-型共掺元素,采用溶胶–凝胶法与溶剂热法相结合的方法制备了氮、铬共掺杂纳米TiO₂粉体。利用X射线衍射（XRD）、透射电镜（TEM）、和紫外–可见光光度计（UV-Vis DRS）等手段对各试样进行表征。结果表明:钛氮铬摩尔比为1:2:10%时共掺杂二氧化钛的粒径可减小至9nm,而且其特征吸收峰红移至400nm处,可见光区光吸收强度也明显增大,从而有效提高了光催化性能。由实验数据推算出二氧化钛的原始带隙减小至1.8 eV,理论模型计算的带隙减小趋势与实验相一致。2、补偿性掺杂:对于p-型共掺元素,钒氮掺杂TiO₂粉末也是通过溶剂热法制备的。当氮源为尿素,钒源为五氧化二钒时制备的掺杂TiO₂粉体,通过XPS表征得出氮钒原子分别以间隙、五价替换的形式掺入到晶格中。钛氮钒摩尔比为1:1:16%时共掺杂试样在紫外区和可见光区的吸收强度均大大超过空白样。该样品在紫外光下照射30min后对亚甲基蓝的降解率达到90%多。当氮源为尿素,钒源为乙酰丙酮氧钒时制备的掺杂TiO₂粉体粒径能达到10nm左右。Ti,N,V摩尔比为1:2:16%时共掺试样在所有试样中的吸收效果最好,并且钒氮共掺杂二氧化钛在30min内对亚甲基蓝的降解率能达到大约90%,有效的提高了光催化效率。更多还原

【Abstract】 Owing to nontoxicity, high efficiency, low cost and stable performance corrosion resistance, titania has been the best promising materials. However, due to its wide bandgap （3.2eV for anatase）, TiO₂ can be excited only with UV light, which accounts for only a small fraction of solar light （5%）. Therefore, it is highly desirable to develop TiO₂-based photocatalysts with enhanced activities under visible light. For the sake of efficient use of sunlight, the technology of enlarging the absorption scope of TiO₂ by doping or modifying TiO₂ may then appear as an appealing challenge for developing the future generation of photocatalysts.In order to overcome this limitation, this research focuses on the doping modification of TiO₂ which can inhibit the recombination of photo-generated electron-hole pairs. All of these are to find a best mode to improve photocatalysis efficiency so that TiO₂ can take full advantage of visible light. Research contents and results are as follows:1. Noncompensated doping: For the n-type codoped elements, the chromium and nitrogen doped TiO₂ nanoparticle was prepared by the solvothermal method and sol-gel method. These samples were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM） and UV-visible light photometer （UV-Vis DRS）. The results showed that the particle size of the codoped titania is narrowed to about 9 nm when the molar ratio of Ti, N, O is 1:2:10%. The absorption peak redshifts to 400nm and the light absorption intensity also increased in order to effectively improve the photocatalytic activity. The intrinsic band gap calculated from the experimental data is narrowed to 1.8 eV for co-doping, and the variation tendency of the bandgap is consistent with that of the experiment.2. Compensated doping: For the p-type codoped elements,? the vanadium and nitrogen doped TiO₂ sample was also prepared by the solvothermal method. When the nitrogen source is urea and the vanadium source is V2O5, the nitrogen\ vanadium atom is incorporated into the crystal lattice in the form of interstitial and V5+, respectively. The indentity of codoped sample exceed greatly that of pure one both under UV light irradiation and visible light irradiation.The degradation rate for methylene blue of N/V-TiO₂ comes up to more than ninety percent after 30min.When the nitrogen source is urea and the vanadium source is C10H14O5V, the size of codoping TiO₂ powders can achieve around 10nm. The light absorption effect of codoped titania （Ti: N: V=1:2:16%） is the best in all samples. The degradation rate for methylene blue of N/V-TiO₂ is ninety percent after 30min.更多还原