钼酸铋纳米材料的制备与光催化性能研究

发布时间：2018-03-26 11:01

本文选题：钼酸铋　切入点：水热/溶剂热法　出处：《西安科技大学》2017年硕士论文

【摘要】：半导体光催化技术和光催化材料是解决当前能源匮乏和环境污染的有效手段和研究热点。在众多光催化材料中,钼酸铋具有简单的奥里维里斯(Aurivillius)层状结构,良好的可见光响应能力,在环境污染物处理、太阳能光解产氢、气敏传感等方面都表现出优异的性能。但是,钼酸铋光催化剂距离实际应用仍有不少技术瓶颈,如优化合成工艺、设计和制备新的催化剂结构、进一步提高可见光催化性能。本文将着眼于光催化性能优化,研究了表面活性剂对水热法、溶剂热法合成钼酸铋形貌和催化性能的影响,并通过纳米银负载和半导体Bi2S3复合两种方式进一步提高钼酸铋的可见光催化性能,主要的研究内容和结论如下:为分析表面活性剂对钼酸铋合成、结构与性能的影响,采用不同表面活性剂,通过水热法优化制备了 Bi_2MoO_6纳米片。研究了表面活性剂种类(CTAB、KBr、PVP、PEG)对Bi_2MoO_6片状结构的影响,并探讨了其生长机理,其中采用CTAB可以获得均匀的钼酸铋纳米片。当CTAB=0.15g时,合成的纳米片厚度仅为5～15nm,比表面积为20.551 m2/g。与钼酸铋纳米粉体相比,CTAB辅助制备的钼酸铋纳米薄片具有更强的光吸收,低的禁带宽度和更优的光催化活性,3 h光照后,亚甲基蓝(MB)降解率达到81%。以CTAB为表面活性剂,采用乙二醇/水混合溶剂热法进一步合成了花簇状Bi_2MoO_6微米球。Bi_2MoO_6微米花簇球是由厚度为10～20 mm的纳米片自组装而成的。通过改变混合溶剂比可以实现Bi_2MoO_6微米球的形貌和尺寸调控,分析了花簇状微米球生长机理。EG:H2O=8:2时,合成的Bi_2MoO_6花簇状中空结构比薄片和花簇状微米球具有更优的光催化活性,3 h光照后,MB降解率达到98%。基于上述混合溶剂热法,分别通过一步溶剂热法和光致还原法合成了 Ag负载的Ag/Bi_2MoO_6复合纳米材料。结果表明,采用一步溶剂热法制备的中空球状Ag/Bi_2MoO_6(Ag=6wt%)较光致还原法制备的样品具有更窄的禁带宽度,因而拥有更优的可见光吸收效果,在此基础上进一步探讨了中空球生长机理。以一步溶剂热法制备的Ag/Bi_2MoO_6样品为光催化剂,经3 h光照后,MB降解率达到90.2%。基于混合溶剂热法,通过一步溶剂热法制备了纳米棒-微米球Bi2S3/Bi_2MoO_6复合结构。这种结构中,光生电子可以在Bi2S3和Bi_2MoO_6形成的界面上传输,使光生电子-空穴对能够得到有效分离,提高载流子的迁移速率。制备的Bi2S3/Bi_2MoO_6复合结构的光催化性能明显优于相同条件下制备的Bi_2MoO_6微米球,经3 h光照后,MB的降解率达到83%。
[Abstract]:Semiconductor photocatalysis and photocatalytic material is an effective means to solve the energy shortage and environmental pollution and research hotspot. In many photocatalytic materials, bismuth molybdate has a simple Olive Chis (Aurivillius) layered structure, visible light response ability, in environmental pollutant treatment, hydrogen production by solar energy, gas sensing etc. have shown excellent performance. However, bismuth molybdate photocatalyst from practical applications there are still many technical bottlenecks, such as optimizing the synthesis process, design and preparation of new catalyst structure, to further improve the photocatalytic performance. This paper will focus on the photocatalytic performance optimization of surfactant by hydrothermal method, influence solvothermal synthesis of bismuth molybdate morphology and catalytic properties, and the nano silver composite semiconductor Bi2S3 load and two ways to further improve the bismuth molybdate visible light catalytic performance, the main The research contents and conclusions are as follows: for the analysis of surfactants on the synthesis of bismuth molybdate, affecting the structure and properties, using different surfactants, Bi_2MoO_6 nanosheets were prepared by hydrothermal method. The optimization of different kinds of surfactants (CTAB, KBr, PVP, PEG) effect on Bi_2MoO_6 sheet structure. And discussed the growth mechanism, in which the CTAB can obtain uniform bismuth molybdate nano film. When CTAB=0.15g, the synthesis of nano film thickness is only 5 ~ 15nm, compared to the surface area of 20.551 m2/g. and bismuth molybdate nano powder, bismuth molybdate nano sheet CTAB assisted preparation has stronger optical absorption band the width of low and better photocatalytic activity, 3 h after irradiation, methylene blue (MB) degradation rate of 81%. with CTAB as surfactant, using ethylene glycol / water mixed solvent thermal method to synthesize flower like Bi_2MoO_6 microspheres.Bi_2MoO_6 micron. The ball is made by the thickness of 10~20 mm nanosheets assembled. By changing the mixed solvent ratio morphology and size control can be achieved Bi_2MoO_6 microspheres, analyzed the growth mechanism of.EG:H2O=8:2 flower like microspheres, Bi_2MoO_6 flower like hollow structure synthesis has better photocatalytic activity than thin and flower clusters of micron the ball, 3 h after irradiation, the degradation rate of MB to 98%. of the mixed solvent thermal method based on respectively by one-step solvothermal method and Photoluminescence of Ag/Bi_2MoO_6 nanocomposites synthesized Ag load reduction method. The results showed that by one-step solvothermal method for preparation of hollow spherical Ag/Bi_2MoO_6 (Ag=6wt%) is the light induced reduction the samples prepared by band gap is narrower, so it has better absorption of visible light, on this basis to further explore the growth mechanism of hollow spheres by one step. The solvothermal samples for Ag/Bi_2MoO_6 The photocatalyst, after 3 h of irradiation, the degradation rate of MB to 90.2%. mixed solvothermal method based on micro sphere Bi2S3/Bi_2MoO_6 nanorods composite structure prepared by one-step solvothermal method. In this structure, the photogenerated electrons can be formed in the Bi2S3 and Bi_2MoO_6 interface transmission, so that the photogenerated electron hole pairs can be obtained effective separation, improve the migration rate of carrier. The photocatalytic properties of Bi2S3/Bi_2MoO_6 composite prepared under the same conditions was better than that of Bi_2MoO_6 microspheres prepared by the 3 h after irradiation, the degradation rate of MB reached 83%.

【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ135.32;TB383.1

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