【作者】 张胜渠；

【导师】 郭伊荇；

【作者基本信息】 东北师范大学 ， 物理化学， 2013， 博士

【摘要】 TiO₂半导体材料因具有无毒、无害、廉价、稳定、高催化性能等优点，而成为一种理想的光催化材料。但是由于其带隙能较大，只能被占太阳光不到5%的紫外光激发，太阳光利用率较低；此外，TiO₂表面产生的电子–空穴对复合几率较高，导致其量子效率较低。这些都限制了TiO₂的实际应用。因此研制具有较高光催化性能的新型光催化材料成为当前科研工作者的研究重点。另外，开发以太阳光为光源的高效光催化反应器是提高光催化体系能效和活性的另一重要途径。虽然传统的悬浮型光催化反应器构造设计简单，催化剂担载量高，但存在催化剂分离困难，光照不均匀，光利用率低等问题，从而使得这种反应器局限于实验室研究。因此，本文致力于设计和制备具有较高太阳光光催化活性的新型复合光催化材料，并研制一种新型高效的光催化反应器。通过各种分析测试方法对光催化材料的结构和形貌进行表征，并系统地考察其在新型反应器中的模拟太阳光催化性能。本论文具体的研究内容如下：1.采用溶胶凝胶结合溶剂热技术制备了H₃PW₁₂O₄₀/TiO₂复合材料，采用浸渍提拉的方法把H₃PW₁₂O₄₀/TiO₂复合材料涂覆到光纤的表面，采用光沉积技术在光纤的表面制备了Ag/H₃PW₁₂O₄₀/TiO₂异质结薄膜复合材料。通过X射线粉末衍射仪（XRD）、傅里叶变换红外光谱仪（FT IR）、电感耦合等离子体原子发射光谱仪（ICP AES）、X射线光电子能谱仪（XPS）、透射电子显微镜（TEM）、场发射扫描电子显微镜（FESEM）、紫外可见漫反射光谱仪（UV vis/DRS）和N2吸附脱附等现代检测技术对复合光催化材料的组成结构、形貌、光吸收性质以及孔隙率进行了全面表征。通过在模拟太阳光的照射下，对染料罗丹明B（RB）和对硝基苯酚（4NP）的降解评价了各种催化剂薄膜的光催化活性；通过六次降解RB循环实验，评价了H₃PW₁₂O₄₀/TiO₂和Ag/H₃PW₁₂O₄₀/TiO₂1薄膜的循环使用情况；把涂覆有催化剂薄膜的光纤垂直均匀地放置在石英反应器中，成功设计了新型的光纤反应器。在新型光纤反应器中，涂覆催化剂的光纤束不仅仅是催化剂薄膜的载体，而且又是光的传播媒介，因此，光纤反应器提高了光利用率，光纤反应器对RB和4NP的降解速率明显高于光纤水平放置仅作为催化剂载体时的光催化速率。新型高效的光催化剂与新型的光纤反应器相结合，大大提高了整个反应体系对污染物的降解能力。2.分别采用热缩聚和溶剂热方法制备了石墨相C3N4（g-C₃N₄）和Bi₅Nb₃O₁₅，以制备的g-C₃N₄和Bi₅Nb₃O₁₅为原料，通过研磨热处理的方法制备了g-C₃N₄/Bi₅Nb₃O₁₅复合光催化材料。采用XRD、FT IR、TEM、UV vis/DRS和荧光光谱（PL）等现代检测技术，对复合光催化材料的组成结构、形貌和光吸收性质等进行了系列表征。通过可见光下对染料甲基橙（MO）和对氯苯酚（4CP）的降解评价了制备的g-C₃N₄/Bi₅Nb₃O₁₅光催化材料的催化性能。结果表明，在适当的g-C₃N₄担载量下，g-C₃N₄/Bi₅Nb₃O₁₅的可见光催化活性显著优于纯g-C₃N₄和Bi₅Nb₃O₁₅；通过自由基和空穴捕获实验，研究了4-CP降解过程中的主要活性物钟，提出了可能的降解机理；通过五次循环实验评价了制备的g-C₃N₄/Bi₅Nb₃O₁₅的循环使用情况。通过光电化学实验和荧光光谱分析研究了g-C₃N₄/Bi₅Nb₃O₁₅复合光催化材料中光生电子和空穴的分离和迁移情况；通过g-C₃N₄/Bi₅Nb₃O₁₅复合材料能带结构的提出，理论上研究了光生电子和空穴分离和迁移的过程，为复合光催化材料的构筑提供了理论依据。更多还原

【Abstract】 TiO₂semiconductor has been considered a kind of ideal photocatalytic material due to itsnon-toxic, low cost, high stability and superior photocatalytic properties. However, TiO₂canutilize no more than5%of the total solar energy impinging on the surface of the earth due toits wide bandgap. Moreover, the photogenerated electrons and holes of TiO₂can recombinerapidly, which results in the low quantum efficiency. These restrict the practical application ofTiO₂. Therefore, much effort has been devoted to developing more efficient and stablephotocatalysts. In addition, the design of highly efficient photoreactors is also crucial to thewide range of needs for environmental remediation and clean-up. Conventionally usedphotoreactors for liquid phase oxidation are based on the heterogeneous slurry system withsuspended catalyst. The design offers ease of construction and high catalyst loading. However,slurry reactors are limited to the laboratory scale for wastewater treatment because ofdifficulty of separation of photocatalyst nanoparticles from the treated water and nonuniformlight irradiation and low light utilization efficiency. Therefore, we devote ourselves to designand development of new and efficient composite photocatalyst with higher photocatalyticactivity and a new photoreactor. The photocatalytic materials were well characterized bymany techniques. And the photocatalytic activities were investigated systemically in thedesigned photoreactor under simulated sunlight irradiation.1. H₃PW₁₂O₄₀/TiO₂composite photocatalytic material was prepared by combination ofthe methods of sol gel and hydrothermal treatment at a lower temperature. AndH₃PW₁₂O₄₀/TiO₂-coated optical fibers were prepared by dip coating method. The Agnanoparticles were photodeposited on the surface of H₃PW₁₂O₄₀/TiO₂films coated on theoptical fibers. The photocatalysts were characterized by X ray diffraction （XRD）, FourierTransform Infrared Spectrometer （FT IR）, Inductively Coupled Plasma Atomic EmissionSpectrometer （ICP AES）, X ray photoelectron spectroscopy （XPS）, transmission electronmicroscopy （TEM）, field emission scanning electron microscopy （FESEM）, UV Vis diffusereflectance spectra （UV Vis/DRS） and N2adsorption/desorption. Their photocatalyticactivities were evaluated by degradation of aqueous RB and4NP under the simulatedsunlight irradiation. The recyclability of the H₃PW₁₂O₄₀/TiO₂and Ag/H₃PW₁₂O₄₀/TiO₂1filmwas evaluated through six consecutive catalytic cycles. The optical fiber reactor was designedby puting H₃PW₁₂O₄₀/TiO₂or Ag/H₃PW₁₂O₄₀/TiO₂1film coated optical fiber bundlevertically in the quartz reactor. In this design, the optical fibers act as not only supporter of thecomposites film but also the medium of light transmission. Therefore, this new type optical fiber reactor enhances the light use efficiency, which results to the enhanced photodegradationefficiency.2. g-C₃N₄and Bi₅Nb₃O₁₅were prepared by polycondensation and hydrothermaltreatment method respectively. g-C₃N₄/Bi₅Nb₃O₁₅composite photocatalytic materials wereprepared by a simple milling heat treatment method with g-C₃N₄and Bi₅Nb₃O₁₅as rawmaterials. The g-C₃N₄/Bi₅Nb₃O₁₅composites were characterized by XRD, FT IR, TEM,UV vis/DRS and PL. The photocatalytic activities of g-C₃N₄/Bi₅Nb₃O₁₅were evaluated bydegradation of aqueous MO and4CP under the visible light irradiation. At proper g-C₃N₄loading, the photocatalytic activity of g-C₃N₄/Bi₅Nb₃O₁₅outperforms pure g-C₃N₄andBi₅Nb₃O₁₅. The main active species yielded in the g-C₃N₄-and g-C₃N₄/Bi₅Nb₃O₁₅-catalyzed4CP degradation systems were also investigated by the free radical and hole scavengingexperiments. Accordingly, the photodegradation mechanism was given. Andg-C₃N₄/Bi₅Nb₃O₁₅–70was chosen to evaluate the recyclability of the g-C₃N₄/Bi₅Nb₃O₁₅photocatalysts by five times’RB degradation reaction.The separation and transportation of photogenerated electrons and holes wereinvestigated by photoelectrochemistry experiments and fluorescence spectra analysis. Thespecific process of the transportation of photogenerated carriers was studied by the bandstructure, which provided theoretical basis for the design of composite photocatalysts.更多还原