【作者】 仇满德；

【导师】 姚子华；

【作者基本信息】 河北大学 ， 分析化学， 2009， 博士

【摘要】 本论文以氧化锌稀磁半导体和纳米二氧化钛光催化剂材料为研究对象,针对目前这一领域需要解决的一些问题,将表面微分析技术应用于它们的研究。一方面,探求了制备条件与材料组成、微结构、形貌以及性能的关系；另一方面,研究了载体、外加磁场等对纳米二氧化钛光催化性质的影响,并成功制备了具有实际应用前景的新型阳离子聚丙烯酰胺/TiO2复合絮凝剂。全文共分为以下6个部分。第1章为绪论部分,针对功能金属氧化物半导体材料的光催化和稀磁特性,介绍了金属氧化物半导体材料的制备方法、研究进展及微区分析技术,同时展望了其应用前景。第2章利用表面微区分析方法系统研究了掺杂元素对氧化锌基稀磁半导体结晶生长的影响。通过水热法制备了不同过渡金属掺杂的ZnO基稀磁半导体晶体,利用扫描电子显微镜(SEM)及X射线能谱仪(XREDS)对合成晶体的微观形貌、表面及内部剖面掺杂元素的相对含量和分布进行了研究。研究发现过渡金属掺杂离子影响ZnO晶体的生长,掺杂离子的不同其大小、形貌均有所差异,随晶体形貌不同,显露面也发生了相应改变。X射线微分析证实,晶体表面与晶体内部掺杂离子分布相对均匀,Co、Mn离子比Fe、Ni离子容易实现掺杂,Fe, Ni离子不容易或少量的进入到晶格中。另外还研究了In离子与过渡金属共掺杂对ZnO晶体极性生长的影响,并从水热理论探讨了晶体生长的影响因素及机理。第3章对纳米二氧化钛的制备工艺、微结构及性能进行了研究。本章共分为两节。在第一节中,采用溶胶-凝胶法在玻片上制备了纳米TiO2薄膜,并利用扫描探针显微镜对薄膜的微结构、透光率进行了分析,结果表明制备的TiO2薄膜为均匀突起的锐钛矿型纳米TiO2薄膜,同时探讨了微结构同光催化性能的关系。在第二节中,主要横向比较了常规不同液相制备方法对纳米TiO2粉体的微结构与光催化性能的影响,并从晶体表面结晶度、晶格缺陷以及TiO2表面羟基分布等方面对光催化活性差异的原因进行了初步探讨。第4章为粉煤灰负载纳米TiO2的微分析及应用研究。在本章中,利用XRD, SEM及EDS对粉煤灰原灰以及水、磁筛选的粉煤灰进行了物相、表面微结构及X射线微区分析的系统研究,对各种粉煤灰的特征有了较清楚的认识,为粉煤灰的开发利用提供了有用的信息。在此基础上,采用溶胶-凝胶法在粉煤灰沉珠上负载了纳米TiO2薄膜,探讨了其光催化降解性能与载体效应之间的关系。第5章为了进一步提高纳米二氧化钛的光催化性能,研究了磁场对纳米二氧化钛光催化性能的影响,重点研究了不同磁场强度及固定磁场强度下体系pH的变化对纳米TiO2的光催化降解性能的影响,证明磁场对增强光催化作用有一定效果。并探讨了磁场在光催化降解过程中的作用机理。第6章将纳米TiO2进行表面处理,与合成的阳离子聚丙烯酰胺P(DMC-AM)成功复合,制备了一种新型的P(DMC-AM)/TiO2复合絮凝剂,该复合絮凝剂光催化吸附降解性能明显的提高,1.5h可使染料脱色率达到95%,具有重要的实际应用价值。更多还原

【Abstract】 In this thesis, some relevant problems of diluted magnetic semiconductor (DMS) ZnO and nano-TiO2 photocatalyst material were mainly studied by the surface micro-analysis methods. The aim is twofold. The former is to find the relationship between the preparation conditions and material composition, microstructure, morphology, performance and application. The latter is to investigate the effect the carrier and magnetic field on the photocatalytic properties nano-TiO2. Moreover, the cationic polyacrylamide/TiO2 composite flocculant were also prepared, which displays some practical application prospect. The whole paper consists of the following six chapters.ChapterⅠ. In this chapter, the photocatalytic properties and diluted magnetic specialities of functional metal-oxide semiconductor materials are summarized. Meanwhile, the relevant preparation methods, the current research progress and micro-area analysis techniques were introduced.ChapterⅡ. In this chapter we studied doped elements on zinc oxide-based diluted magnetic semiconductor crystal growth for the preparation and microanalysis. Mainly, different transition metal(TM) doped ZnO-based diluted magnetic semiconductor (ZnO-DMS) crystals were synthesized by hydrothermal method. Then the morphology and the relative content and distribution uniformity of the surface and inner TM element of synthesizing crystals were investigated by the scanning electron microscope (SEM) and x-ray energy dispersive spectrometry(XREDS), respectively. The studies show that the effect of different doped-TMed on the growth, size and morphology of ZnO crystal. In addition, it is found that the exposed face also changed with crystal morphology. Furthermore, the X-ray micro-analysis confirmed that the doped-ions distributed homogeneously in crystal surface and crystal inner, relatively. These result showed that the ions of Co and Mn were easier doping than Fe and Ni. Meanwhile, the morphologic effect of In and TM codoping ZnO crystals on polarity growth was also studied and as result, the mechanism and the relevant factors affected the crystal growth were discussed by hydrothermal theory.ChapterⅢ. The preparation, microstructure and properties of nano-titanium dioxide (TiO2) are presented. This chapter included two parts. In the first section, uniform anatase nano-TiO2 thin films were prepared by using sol-gel method on the ordinary glass. The microstructure and transmission rate of thin film were investigated by scanning probe microscope(SPM). The study showed that the prepared thin films were with uniformly convex anatase nano-TiO2. On the basis of analysis, the relationship between the photocatalytic properties and microstructure were discussed. In the second section, the main comparison of microstructure and photocatalytic properties of nano-TiO2 powders prepared by three different liquid wet chemical methods(i.e.,sol-gel, liquid deposition and Hydrothermal) are made. The relation between the microstructure and the photocatalytic property has been studied. Correspondingly, the reasons of different photocatalytic activity have been discussed from the crystal surface crystallinity, lattice defects, as well as the distribution of surface hydroxyl on TiO2 surface.ChapterⅣ. The investigations are focused on the microanalysis of fly ash for loading nano-TiO2 layer and its application. At first, Fly ash was separated by water and magnetism methods, and then their phase composition, microstructure and x-ray microanalysis were studied by XRD, SEM and EDS. The microstructure properties of fly ash have been understood, which provided useful information for the development and utilization of fly ash. In terms of this, the surface of fly ash particle was loaded nano-TiO2 film by sol-gel method, and then the relationship between the photocatalytic degradation performance and carrier effect are discussed.ChapterⅤ. The effect of nano-TiO2 photocatalytic capability under magnetic field condition is performed in order to improve nano-TiO2 photocatalytic properties. In this chapter, the effect of different magnetic field strength and values of the pH on nano-TiO2 photocatalytic degradation performance was studied. The results showed that the magnetic field had the significant effects on its photocatalysis property. Meanwhile, the mechanism was also discussed.ChapterⅥ. The nano-TiO2 particles are applied to composite flocculant material. In this chapter, the nano-TiO2 is treated with appropriate surfactant, and then the new cationic polyacrylamide P(DMC-AM)/TiO2 composite flocculant was synthesized. The results show that, P(DMC-AM)/TiO2 composite flocculant have the best decoloring performance and important practical application. In detail, the decolorization rate of can reach in 95% at 1.5h.更多还原