【作者】 王百齐；

【导师】 付宏刚；

【作者基本信息】 哈尔滨工业大学 ， 应用化学， 2006， 博士

【摘要】 通过过渡金属离子掺杂、表面活性剂表面修饰以及染料敏化等方法对纳米TiO₂进行改性,并利用现代测试技术,如表面光电压谱（SPS）和光致发光光谱（PL）等,重点揭示改性方法对光生电荷在纳米TiO₂表界面分离的影响机制。以Zn为过渡金属元素的代表,对纳米TiO₂进行掺杂改性。主要考察了不同焙烧温度、Zn量对TiO₂晶相结构和表面结构等的影响,重点研究了Zn掺杂对纳米TiO₂光生载流子的分离以及光催化性能的影响。结果表明:Zn的掺杂改性能够轻微促进TiO₂由锐钛矿相向金红石相的转变;经450℃焙烧,3 %Zn掺杂改性的样品具有较高的光生载流子分离效率以及较为丰富的表面态,从而使得TiO₂具有较高的光催化活性。Zn的掺杂改性同样可以提高TiO₂粒子膜的光催化活性。此外,在成膜过程中,十二烷基苯磺酸钠（DBS）的加入能够有效地提高薄膜的表面积,进一步提高了粒子膜的光催化活性。利用阴离子表面活性剂DBS和阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）对纳米TiO₂表面进行修饰,探索了表面修饰的适宜条件,并分析了表面修饰机制;重点研究了表面活性剂的修饰对纳米TiO₂光生电荷分离以及光催化活性的影响。结果表明:在适宜的pH范围和表面活性剂用量条件下,DBS和CTAB基团能够较好地修饰在TiO₂纳米粒子表面,实现TiO₂由水相到有机相的相转移过程。两种表面活性剂的修饰机制是不同的,DBS与静电吸引作用有关,而CTAB不仅与静电作用有关而且还可能与氢键作用有关。在合适的pH值范围内,DBS和CTAB适宜的用量范围均约为1%³%,最佳用量在2%左右。由于DBS和CTAB具有相近的摩尔质量,因此说明每个TiO₂纳米粒子表面与表面活性剂分子相联接的活性位数是一定的。此外,缓冲溶液的组分对修饰效果有较大的影响。表面修饰DBS和CTAB后,纳米TiO₂的光催化活性得以提高,这与SPS和电场诱导表面光电压谱（EFISPS）表征结果是相符合的。表面活性剂分子在TiO₂表面的修饰可能影响了其对光子的吸收,从而减弱SPS响应信号的强度。另外,DBS和CTAB分子基团分别通过S和N原子与TiO₂表面相互作用,S和N的吸电子作用使得光生电子到达纳米TiO₂表面的几率增大,改善光生电子与空穴的分离,降低SPS信号响应强度。EFISPS响应信号阈值红移表明DBS和CTAB的更多还原

【Abstract】 In this work, the nanosized TiO₂ was modified by transition metal doping, surfactant surface capping and dye sensitization methods, the as-prepared samples were characterized by modern testing methods, such as surface photovoltage spectrum （SPS） and photoluminescence （PL）, and the influence mechanisms of modification were principally investigated.Nanosized TiO₂ doped with Zn was prepared by a sol-hydrothermal process. The influences of different calcination temperature and Zn content on the TiO₂ crystal structure and surface structure were studied and the effect of Zn-doping on photoinduced charge separation and photocatalytic activity were principally investigated. The results show that Zn can slightly promote the TiO₂ phase transiton from anatase to rutile, the appropriate calcinations temperature and Zn-doping content can improve the photoindcued charge separation and surface state of TiO₂, which are responsible for the enhancement of TiO₂ photocatalytic performance. Zn-doping can also increase photocatalytic activity of TiO₂ film. In additon, the added sodium dodecylbenzenesulfonate （DBS） in preparation process of film can enlarge film surface.The nanosized TiO₂ capped with DBS and cethyltrimethylammonium bromide （CTAB） were prepared, respectively. The proper modification conditions were explored, and capping mechanisms were discussed in detail. The influences of modification on photoinduced charge transfer and photocatalytic performance were investigated, in principle. The results show that DBS and CTAB groups can cap TiO₂ surface under conditions of appropriate pH value and surfactant amounts. The capping mechansims of DBS and CTAB are very different, the former is close related to electrostatic attraction, and the latter is not only related to electrostatic attraction, but to hydrogen bond. The appropriate amounts of two surfactant groups are in the range of 1 % 3 % compared to TiO₂ mass, and the optimal amount is about 2 %, indicating that there is a certain number of surface active site on a TiO₂ particle. In addition, the buffer system can influence the capping effect.The photocatalytic activity of TiO₂ increases after its surface is capped by DBS更多还原