纳米金属氧化物的设计和光催化性能研究
发布时间：2018-11-25 15:34
【摘要】：金属氧化物半导体纳米材料在紫外光照下能产生大量的电子和空穴对,从而具有氧化还原性,可以应用于光催化降解水中的有机污染物,而且材料的化学性质稳定、来源广泛、成本低廉、环境友好,在光催化处理水污染方向有良好的应用前景。但由于材料在制备时不易形成稳定的结构,一般粒径较大,产物可利用的比表面小,而且半导体材料的禁带宽度较宽,只能被日光中不到5%的紫外光激发,半导体材料的光生电子和空穴极易复合,对有机染料的降解率不高,限制了材料在光催化方面的应用。本文旨在设计不同形貌结构的纳米金属氧化物,通过构筑一些独特的结构来提高对有机染料的吸附能力,从而提高材料对有机染料的光催化降解效率。论文主要制备了两种特殊形貌的纳米金属氧化物:具有纳米通孔的空心CuO微球和混相C/TiO_2纳米球及其复合物。1)通过SiO_2模板辅助在水热条件下合成制备一种具有开放纳米孔洞的空心CuO微球。以硅酸钠作为碱性介质相当于SiO_2前驱体,CuSO_4和葡萄糖分别作为铜源和还原剂。上述合成产物在600℃高温煅烧后,由Cu_2O/Si O_2混合物完全转变为CuO/SiO_2,最后经由NaOH刻蚀法除去SiO_2,产物干燥后即得到具有开放纳米孔洞的空心CuO微球。对产物进行表征发现CuO微球由大量微小CuO晶体颗粒组成,产物的空心内层结构和开放纳米孔洞结构来源于SiO_2模板的去除。文章同时研究了硅酸钠的含量对于产物结构的影响,结果表明只有当硅酸钠达到一定含量时才能形成CuO微球。此外,还提出了这种纳米结构可能的形成机理,并探究了CuO微球在紫外光下对甲基橙(MO)的光催化降解,结果表明材料在75 min内能完全降解MO,相同条件下CuO微球表现出远优秀于商业CuO(~200 nm)的光催化活性,并且催化剂稳定性高。2)制备了混晶(锐钛矿相和金红石相)和纯锐钛矿相TiO_2纳米球(200 nm~400 nm)和金属氧化物负载TiO_2复合材料。以PVP,葡萄糖为形貌结构调节剂与钛前驱体水热作用,得到尺寸均一的混晶和纯锐钛矿C/TiO_2球形颗粒。通过研究发现:反应物种类、钛源、还原剂的含量、Ti~(4+)的浓度等因素对制备TiO_2纳米球的物相和形貌有着显著的影响。另外,详细研究了这些微球在可见光条件下对有机染料例如亚甲基蓝(MB)、甲基橙(MO)、罗丹明(RhB)的光催化降解性能。结果显示它们对MB染料的降解效果最好。探究了TiO_2及其复合材料在可见光下对一些染料(亚甲基蓝(MB)、甲基橙(MO)、罗丹明B(RhB))的光催化性能,发现材料对MB染料的降解效果最好。其中TiO_2纳米球和CuO/TiO_2都可以在30 min内完全降解MB染料,60 min内降解RhB染料达95%以上,相比商业P25表现出更好的催化效果。通过4次循环降解实验,材料仍具有超过70%的降解效率,这表明锐钛矿TiO_2及其复合材料具有稳定的可见光催化性能。
[Abstract]:Metal oxide semiconductor nanomaterials can produce a large number of electron and hole pairs under ultraviolet light, so they can be redox and can be used in photocatalytic degradation of organic pollutants in water. Moreover, the materials have stable chemical properties and a wide range of sources. It is low cost and environment friendly. It has good application prospect in photocatalytic treatment of water pollution. However, it is not easy to form a stable structure when the material is prepared, the particle size is larger, the specific surface of the product is small, and the band gap of semiconductor material is wider, which can only be excited by less than 5% ultraviolet light in sunlight. The photogenerated electrons and holes of semiconductor materials are easy to be recombined, and the degradation rate of organic dyes is not high, which limits the application of semiconductor materials in photocatalysis. The purpose of this paper is to design nanometallic oxides with different morphologies, and to improve the adsorption ability of organic dyes by constructing some unique structures, so as to improve the photocatalytic degradation efficiency of organic dyes. Two kinds of nanometallic oxides with special morphology were prepared in this paper: hollow CuO microspheres with nanorods and miscible C/TiO_2 nanospheres and their complexes. 1) Synthesis under hydrothermal conditions assisted by SiO_2 template A hollow CuO microsphere with open nano hole was prepared. Sodium silicate as basic medium is equivalent to SiO_2 precursor, CuSO_4 and glucose are used as copper source and reducing agent, respectively. After calcined at 600 鈩，
本文编号：2356616
[Abstract]:Metal oxide semiconductor nanomaterials can produce a large number of electron and hole pairs under ultraviolet light, so they can be redox and can be used in photocatalytic degradation of organic pollutants in water. Moreover, the materials have stable chemical properties and a wide range of sources. It is low cost and environment friendly. It has good application prospect in photocatalytic treatment of water pollution. However, it is not easy to form a stable structure when the material is prepared, the particle size is larger, the specific surface of the product is small, and the band gap of semiconductor material is wider, which can only be excited by less than 5% ultraviolet light in sunlight. The photogenerated electrons and holes of semiconductor materials are easy to be recombined, and the degradation rate of organic dyes is not high, which limits the application of semiconductor materials in photocatalysis. The purpose of this paper is to design nanometallic oxides with different morphologies, and to improve the adsorption ability of organic dyes by constructing some unique structures, so as to improve the photocatalytic degradation efficiency of organic dyes. Two kinds of nanometallic oxides with special morphology were prepared in this paper: hollow CuO microspheres with nanorods and miscible C/TiO_2 nanospheres and their complexes. 1) Synthesis under hydrothermal conditions assisted by SiO_2 template A hollow CuO microsphere with open nano hole was prepared. Sodium silicate as basic medium is equivalent to SiO_2 precursor, CuSO_4 and glucose are used as copper source and reducing agent, respectively. After calcined at 600 鈩，
本文编号：2356616
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