纳米半导体材料的低温制备及性能研究

发布时间：2018-05-28 02:01

本文选题：Bi2WO6 + 纳米复合材料　；参考：《南京邮电大学》2015年硕士论文

【摘要】：WO3和Bi2WO6都是n型半导体材料,其中WO3的禁带宽度为2.4-2.9 eV,Bi2WO6为2.8eV。其中Bi2WO6是由[Bi2O2]2+层和WO6八面体层交替排列构成的晶体结构,这种层状结构有利于电荷转移,因此,Bi2WO6能够显示出优良的光催化降解活性。WO3纳米线的比表面积较大,在气敏传感、电致和光致发光、电导电极及光催化等各个方面均具有良好的应用前景,这些都是传统WO3材料无法比拟的。本文所述实验方法打破了常规水热法中对反应容器和反应条件的严苛要求,具有简单易操作,能耗低等优点。对低温制备的各种形貌的样品进行表征、光催化实验及生物应用实验,得到优异效果,并对其相关机理进行了初步探究。具体内容如下:(1)采用低温水热方法制备Bi2WO6过程中,表面活性剂对Bi2WO6形貌有重要影响。原因是表面活性剂提供的模板导向作用不同,溶剂影响奥斯瓦尔德熟化过程中的传质速率,进而影响样品的晶体结构和最终形貌。与传统制备方法相比,本文所采用的低温水热法制备出的Bi2WO6仍拥有非常优异的光催化效果。(2)在95℃低温条件下,Bi(NO3)3?5H2O与预先合成的WO3?nH2O经水热处理可生成Bi2WO6。形成的Bi2WO6/WO3异质结在紫外-可见光区存在强吸收特性,并能显著提高对甲基橙的光催化降解活性。Bi2WO6/WO3异质结为光催化剂对甲基橙的光降解降效果优于单一组分纳米材料。这种增强产生的原因是异质结的紧密接触有利于光生电子传输,并促进电子-空穴对的分离。(3)采用化学沉淀和水热法制备WO3,通过改变各种实验参数,在低于95℃条件下合成出不同形貌的WO3纳米材料。以(NH4)2SO4为表面活性剂可制备出针状的WO3纳米微球。采用一步退火法可以在钨丝衬底上生长出长径比高达400的WO3纳米线,WO3纳米线在电化学及生物检测方面都用重要应用。(4)实验证明不同浓度的纳米Ag和同浓度不同形貌的纳米WO3都具有一定的抑菌杀菌效果。浓度为0.067 M粒径约50 nm的纳米Ag具有明显抑菌杀菌效果。不同形貌的WO3抑菌杀菌效果不同,针状的WO3纳米材料具有较明显的抑菌杀菌效果,推测是WO3纳米线在光照射下作为一种半导体材料具有催化性质,产生了强氧化性的物质。
[Abstract]:Both WO3 and Bi2WO6 are type N semiconductor materials, in which the band gap of WO3 is 2.4-2.9 eV, Bi2WO6 is 2.8eV. and Bi2WO6 is a crystal structure composed of [Bi2O2]2+ layer and WO6 eight surface layer, which is beneficial to the charge transfer. Therefore, Bi2WO6 can show the specific surface area of the excellent photocatalytic degradation activity nanowires. It has a good application prospect in various aspects such as gas sensing, electroluminescence, photoluminescence, conductance electrode and photocatalysis, which are all unparalleled by traditional WO3 materials. The experimental method described in this paper has broken the strict requirements for the reaction vessel and reaction conditions in the conventional hydrothermal method, and has the advantages of simple and easy operation and low energy consumption. The samples of various morphologies prepared at low temperature have been characterized, photocatalytic experiments and biological application experiments have obtained excellent results, and their related mechanisms are preliminarily explored. The specific contents are as follows: (1) the surface active agent has an important influence on the morphology of Bi2WO6 during the preparation of Bi2WO6 by the low temperature hydrothermal method. The reason is the mold provided by the surfactant. The effect of plate guidance on the mass transfer rate in the process of Oswald ripening affects the crystal structure and final morphology of the sample. Compared with the traditional preparation method, the low temperature hydrothermal method used in this paper still has excellent photocatalytic effect. (2) Bi (NO3) 3? 5H2O and advance at low temperature at 95. The synthesized WO3? NH2O can produce the Bi2WO6/WO3 heterojunction formed by Bi2WO6. in the ultraviolet visible light region, and it can significantly improve the photocatalytic degradation of the methyl orange activity.Bi2WO6/WO3 heterojunction, which is better than the single component nanomaterial. The close contact of the heterojunction is beneficial to the photoinduced electron transport and the separation of the electron hole pair. (3) WO3 was prepared by chemical precipitation and hydrothermal method. By changing various experimental parameters, WO3 nanomaterials with different morphologies were synthesized under the conditions of lower than 95 degrees. The needle like WO3 nanospheres could be prepared by (NH4) 2SO4 as a surface active agent. The WO3 nanowires with a length to diameter ratio of 400 can be grown on the tungsten wire substrate by one step annealing. The WO3 nanowires have important applications in electrochemical and biological detection. (4) the experiments show that the nano Ag with different concentrations and the nano WO3 with different morphologies with the same concentration have a certain bactericidal effect. The concentration of 0.067 M particle size is about 50 nm. Ag has obvious bacteriostasis and bactericidal effect. Different morphologies of WO3 have different bacteriostasis and bactericidal effect. The needle like WO3 nanomaterials have obvious bacteriostasis effect. It is speculated that WO3 nanowires have catalytic properties as a kind of semiconductor materials under light irradiation, and produce strong oxidation properties.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304;TB383.1

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