【作者】 夏杰祥；

【导师】 李华明；

【作者基本信息】 江苏大学 ， 环境工程， 2011， 博士

【摘要】 随着现代社会的快速发展,能源短缺和环境污染问题严重影响和威胁着人类的生活。光催化技术是一种绿色高级氧化技术,在环境污染治理领域和能源开发方面有着广泛的研究和应用。开发高效、高稳定性光催化剂已经成为光催化研究的热点问题。本论文旨在探索反应型离子液体中新型高效卤化氧铋催化剂的可控合成及其在环境污染方面应用。并采用XRD、XPS、SEM、TEM、BET、DRS等测试手段对所合成光催化剂的结构、形貌、生长机理及其光催化性能与催化剂结构之间的构效关系进行了深入研究。本文通过碘代1-丁基-3-甲基咪唑反应型离子液体中乙二醇溶剂热合成了多孔结构和表面带一个孔的中空花状结构BiOI材料。通过XRD、SEM、TEM、EDS、BET、DRS等方法对催化剂进行表征分析,并分析了中空结构BiOI材料可能的晶体生长机理。研究结果表明,反应型离子液体不仅起到溶剂和模板剂的作用外,还作为碘源参与BiOI中空、多孔结构材料的合成,离子液体对中空结构材料的形成起到重要的调控作用。可见光照射条件下BiOI材料光催化降解甲基橙环境污染物活性研究发现,合成的中空结构的BiOI材料相对于片状结构的BiOI材料和TiO2 (Degussa, P25)具有更好的光催化降解甲基橙活性,光照180 min对甲基橙的降解率达94%。其构效关系研究表明中空和多孔结构BiOI材料的高活性来源于能带结构、高的比表面积、高体表比以及强光吸收因素的协同作用。本文还通过溴代1-十六烷基-3-甲基咪唑反应型离子液体乙二醇溶剂热方法合成得到了多孔、中空花状结构的BiOBr材料。通过XRD、XPS、SEM、TEM、EDS、BET、DRS等方法对光催化剂进行表征分析。对中空结构的BiOBr晶体的生长机理进行研究,并给出了可能的生长机理。研究发现,反应型离子液体体系中离子液体同时起到溶剂、模板剂和反应源的作用,离子液体有助于中空、多孔BiOBr材料的形成。可见光照射下的光催化降解罗丹明B活性研究表明,多孔结构的BiOBr材料相对于常规方法合成的BiOBr材料和TiO2 (Degussa, P25)具有更好的光催化降解活性,光照105 min,罗丹明B被完全降解。催化剂结构与活性之间构效关系研究发现,中空和多孔结构BiOBr材料的高活性来源于窄的禁带宽度、高的比表面积、小的颗粒尺寸以及强光吸收因素的协同作用。同时,本文还通过氯代1-十六烷基-3-甲基咪唑反应型离子液体溶剂热合成得到了球状、多孔状结构的BiOCl材料。通过XRD、SEM、EDS、DRS等方法对光催化剂进行表征分析。研究表明反应型离子液体同时起到溶剂、模板剂和反应源的作用,对BiOCl材料起到重要的调控作用。同时,研究了离子液体阳离子和溶剂热的溶剂对BiOCl材料结构和形貌的影响。此外,可见光下光催化降解罗丹明B活性研究表明,离子液体-PVP复合体系中合成的BiOCl材料相对于单离子液体体系中合成的BiOCl材料具有更好的光催化降解罗丹明B的活性,BiOCl材料的光催化活性随着离子液体阳离子碳链的增长而增强。此外,1,3-丁二醇中合成的BiOCl材料比同等条件下乙二醇中合成的材料活性强。在上述工作基础上,本文还通过反应型离子液体[C16mim]Cl, [C16mim]Br和[Bmim]I两两结合乙二醇溶剂热合成了花状结构的BiOX1/BiOX2(X1, X2=Cl, Br, I)复合材料。通过XRD、SEM、EDS、DRS等方法对光催化剂进行表征分析。研究发现,离子液体同时起到溶剂、模板剂和反应源的作用,对花状结构BiOX1/BiOX2(X1,X2=C1,Br,I)复合材料的形成起到重要的调控作用。复合材料光学性质研究发现,BiOBr/BiOI, BiOBr/BiOCl和BiOCl/BiOI材料的禁带宽度分别为2.18 eV,2.89 eV和2.39 eV。同时,制备的花状结构BiOCl/BiOI X2=Cl, Br, I)复合材料进行了可见光照射条件下光催化降解罗丹明B(RhB),亚甲基蓝(MB)和甲基橙(MO)污染物活性的考察。研究发现,合成的花状结构的BiOX1/BiOX2(X1, X2=Cl, Br, I)复合材料对三种不同种类的染料污染物均有可见光降解活性,对罗丹明B染料的降解活性最好。此外,本文还通过1-丁基-3-甲基咪唑四氟硼酸盐离子液体辅助热合成方法制备了鸟巢状结构Bi2W06层状结构材料。研究发现Bi2W06材料是由尺寸在18-20 nm直径Bi2WO6纳米片自组装而形成的3-5/μm的鸟巢层状结构。离子液体对鸟巢状结构Bi2W06材料的形成起到重要的作用。紫外漫反射光谱研究发现鸟巢状Bi2W06结构材料相对于片状Bi2W06材料在紫外可见光区存在明显的光吸收增强性能,这可能是由于鸟巢状Bi2W06材料存在散射作用,使得光线的传播路线延长从而增强光吸收。此外,对制备得到的鸟巢状结构的Bi2W06材料进行了可见光照射条件下光催化降解罗丹明B污染物活性的考察。研究发现制备的鸟巢状结构的Bi2W06材料相对于没有离子液体条件下合成的片状Bi2W06材料具有更好的光催化降解罗丹明B的活性。更多还原

【Abstract】 With the development of our society, the problems of energy shortage and environment Pollution affect our living standard. Photocatalytic technology is one kind of green Advanced oxidation technology, which has been widely used in environmental pollutant treatment and energy development. Visible-light-driven photocatalysts with high activity and stability had attracted a great deal of attention. In this paper, it was focused on the synthesis of BiOX visible-light-driven photocatalysts in reactable ionic liquids system. These resulting materials were characterized by XRD、XPS、SEM、TEM、BET、DRS and photocatalytic activity test, the relationship between the structure of the photocatalyst and the photocatalytic activities were also discussed in details.BiOI uniform porous nanospheres and flower-like hollow microspheres with a hole in its surface structures have been synthesized through an EG-assisted solvothermal process in the presence of ionic liquid 1-butyl-3-methylimidazolium iodine ([Bmim]I). The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), nitrogen sorption and diffuse reflectance spectroscopy (DRS). Possible formation mechanism for the growth of hollow microspheres was discussed. During the reactive process, ionic liquid not only acted as solvents and templates but also as I source for the fabrication of BiOI hollow microspheres, and was vital for the structure of hollow microspheres. Additionally, we evaluated the photocatalytic activities of BiOI on the degradation of methyl orange (MO) under visible light irradiation and found that as-prepared BiOI hollow microspheres exhibited higher photocatalytic activity than BiOI nanoplates and TiO2 (Degussa, P25) did. On the basis of such analysis, it can be assumed that the enhanced photocatalytic activities of BiOI hollow microspheres could be ascribed to its energy band structure, high BET surface area, high surface-to-volume ratios and light absorbance.BiOBr uniform flower-like hollow microspheres and porous nanospheres structures have been synthesized through a one-pot EG-assisted solvothermal process in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C16mim]Br). The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS). Possible formation mechanism for the growth of hollow microspheres was discussed. During the reactive process, ionic liquid [C16mim]Br played the role of solvent, reactant and template at the same time. Moreover, the photocatalytic activities of BiOBr flower-like hollow and porous structures were evaluated on the degradation of rhodamine B (RhB) under visible light irradiation. The results assumed that BiOBr porous nanospheres samples showed much higher photocatalytic activity than the conventional method prepared sample and TiO2 (Degussa, P25). The relationship between the structure of the photocatalyst and the photocatalytic activities were also discussed in details, it can be assumed that the enhanced photocatalytic activities of BiOBr materials could be ascribed to a synergetic effect, including high BET surface area, the energy band structure, the smaller particle size and light absorbance.BiOCl uniform flower-like and sphere-like structures have been synthesized through an solvothermal process in the presence of ionic liquid 1-hexadecyl-3-methylimidazolium chloride ([C16mim]C1). The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS). During the reactive process, ionic liquid not only acted as solvents and templates but also as Cl source for the fabrication of BiOCl materials. The influence of the ionic liquid cations and solvothermal solution on the morphology of BiOCl materials was studied in detail. Additionally, the photocatalytic activities of BiOCl crystals on the degradation of rhodamine B (RhB) under visible light irradiation were evaluated. The results showed that flower-like BiOCl structures synthesized with exhibited higher photocatalytic activity than other BiOCl materials and the photocatalytic activities of BiOCl crystals were increased with the increasing alkyl carbon chain of ionic liquid cations.BiOX1/BiOX2(X1, X2=C1, Br, I) uniform flower-like composites have been synthesized through an solvothermal process in the presence of ionic liquid [C16mim]Cl, [C16mim]Br and [Bmim]I. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS). During the reactive process, ionic liquid acted as solvents, templates and halides source for the fabrication of BiOX1/BiOX2(X,, X2=C1, Br, I) materials. The optical properties of BiOX1/BiOX2(X1, X2=C1, Br, I) were studied studied in detail and the band gaps of the as-prepared composites were estimated to about 2.18,2.89, and 2.39 eV for BiOBr/BiOI, BiOBr/BiOCl and BiOCl/BiOI, respectively. Additionally, the photocatalytic activities of BiOX1/BiOX2(X1, X2=C1, Br, I) crystals on the degradation of rhodamine B (RhB), Methylene Blue (MB) and Methyl Orange (MO) under visible light irradiation were evaluated. The results showed that flower-like BiOX1/BiOX2(X1,X2=C1, Br, I) structures synthesized with exhibited good photocatalytic activity of the three types of dye and the photocatalytic activity of RhB was the best. Bi2WO6 uniform hierarchical nest-like structures have been synthesized through an ionic liquid-assisted hydrothermal method in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4). The Bi2WO6 hierarchical structures have an average diameter of about 3-5μm and are assembled by Bi2WO6 nanosheets with size ranging from 18 to 20 nm. The results show that ionic liquid [Bmim]BF4 is vital for the formation of Bi2WO6 nest-like hierarchical structures. The UV-vis diffuse reflectance spectroscopy indicate that Bi2WO6 hierarchical nest-like structures induces a significantly enhanced optical absorbance in the UV-visible region, which is ascribed to multiple scattering within the hierarchical assemblies to the lengthened optical path length for light transporting. Additionally, the photocatalytic activities of Bi2WO6 crystals on the degradation of rhodamine B (RhB) under visible light irradiation were evaluated. The results showed that nest-like Bi2WO6 structures synthesized with exhibited higher photocatalytic activity than Bi2WO6 nanosheets prepared in conventional method.更多还原