基于细菌模板和静电喷雾沉积制备纳米复合材料及其应用

发布时间：2018-04-23 12:00

本文选题：纳米复合材料 + 静电喷雾沉积　；参考：《湖南大学》2015年博士论文

【摘要】：近年来,在能源安全与环境安全等领域出现了日益严峻的问题,人们一直在致力于解决这些严峻的挑战,并研究开发新的材料与技术用于能源存储和高性能传感器。随着人们对材料的要求越来越高,单一组分、结构简单的纳米材料往往不能满足人们要求,因此高性能、具有特殊结构的纳米复合材料受到了越来越多的关注。虽然纳米复合材料拥有优异的的性能,但是其研究尚处于实验室阶段,低成本、规模化制备纳米复合材料依然是一个世界性难题。改进制备工艺、采用廉价的原材料对于控制产物的结构以及降低合成成本有着重要的意义。鉴于此,本论文从结构设计和组分优化的角度出发,探索采用廉价的生物体-细菌作为模板制备纳米复合材料,并尝试使用操作简单、易规模化的静电喷雾沉积技术制备结构独特、性能优异的金属氧化物(金属硫化物)/还原的氧化石墨烯纳米复合材料。在本论文中,我们做了以下几个方面的研究工作:(1)以酵母菌为模板,采用控制沉淀法制备了Co_3O_4修饰的ZnO中空球,其中四氧化三钴的质量分数约为4%。所得中空球基本复制了酵母菌的形貌,球壁厚约100 nm,由粒径约20 nm的小颗粒组成。我们进一步研究了所制备中空球对丙酮的气敏性能。和纯ZnO中空球相比,Co_3O_4修饰ZnO中空球对有毒气体丙酮展示出了更高的灵敏度和更快的响应与恢复。Co_3O_4修饰的ZnO中空球优异的气敏性能一方面取决于其独特的中空结构,该结构便于气体在敏感材料表面快速的扩散;另一方面是由于p型四氧化三钴修饰n型氧化锌,形成p-n结,这种结构能显著提高材料的气敏性能。(2)探索利用静电喷雾沉积技术,采用一步合成策略在集流体上直接制备层状氧化镍(NiO)/还原的氧化石墨烯(rGO)纳米复合材料。我们使用乙酸镍/氧化石墨烯混合溶液作为前驱体,利用静电喷雾沉积技术将复合材料直接沉积在集流体上,在沉积的过程中对集流体加热以分解乙酸镍并还原氧化石墨烯,从而制得NiO/rGO纳米复合材料层层堆积而得的薄膜电极。在电化学测试中,NiO/rGO复合材料表现出了较高的比电容和良好的循环性能。我们在制备电极的过程中避免使用不导电的粘结剂,使大部分活性材料保持了良好的电化学活性。(3)探索利用静电喷雾沉积技术,采用两步合成策略制备Mn_3O_4/rGO柔性电极。首先,采用还原高锰酸钾的方法制备Mn_3O_4片组装而成的小球;然后,将Mn_3O_4与GO混合溶液作为前驱体,利用静电喷雾沉积技术将复合材料直接沉积在碳布上,在加热条件下,氧化石墨烯被还原为rGO。我们对比了传统涂布法制备的柔性电极(CG)和静电喷雾沉积法制备的柔性电极(GM)的电化学性能,发现GM的克容量和循环稳定性要优于CG。在GM电极中,活性材料与集流体接触更加牢固,并有一定的韧性,在反复弯曲时活性材料仍能与集流体充分接触。而CG电极在弯曲时,活性材料碎裂并发生脱落,导致容量损失。(4)探索采用静电喷雾技术制备金属硫化物-还原的氧化石墨烯纳米复合材料。我们采用两步合成策略,运用静电喷雾沉积技术成功制备了细菌插层的Ni_3S_2/rGO。直径约10 nm的Ni_3S_2小颗粒均匀分布在rGO层上,rGO一方面作为载体,可以有效防止Ni_3S_2小颗粒团聚在一起,另一方面能为Ni_3S_2小颗粒提供3维导电网络;将细菌置于rGO层间能有效改善活性材料与电解液的接触,同时有利于离子在活性材料与电解液之间的扩散;我们直接将活性材料沉积在集流体上,能改善活性材料与集流体的接触,降低接触电阻,同时避免使用不导电的粘结剂,使大部分Ni_3S_2小颗粒保持了良好的电化学活性。
[Abstract]:In recent years, more and more serious problems have emerged in the fields of energy security and environmental safety. People have been working to solve these severe challenges and develop new materials and technologies for energy storage and high performance sensors. With the increasing demand for materials, the single component and simple structure of nanomaterials are often used. The nano composite materials with high performance and special structure have attracted more and more attention. Although nanocomposites have excellent properties, their research is still in the laboratory stage. Low cost and large-scale preparation of nanocomposites are still a worldwide problem. Cheap raw materials are of great significance for controlling the structure of the products and reducing the cost of synthesis. In view of this, this paper, from the perspective of structural design and composition optimization, explores the use of cheap organisms - bacteria as templates to prepare nanocomposites, and tries to use simple, easy to scale electrostatic spray deposition technology. Metal oxide (metal sulfide) / reduced graphene oxide nanocomposites with excellent properties are prepared. In this paper, we have done the following research work: (1) the ZnO hollow ball of Co_3O_4 trimming was prepared by the control precipitation method with the yeast as the template, and the mass fraction of the four oxide three cobalt was about 4. The hollow sphere basically replicates the morphology of the yeast, the ball wall is about 100 nm thick and the particle size is about 20 nm. We further studied the gas sensitivity of the hollow sphere to acetone. Compared with the pure ZnO hollow ball, the Co_3O_4 modified ZnO hollow sphere showed higher sensitivity and faster response and recovery to the toxic gas acetone. The excellent gas sensing properties of the compound.Co_3O_4 modified ZnO hollow sphere depend on its unique hollow structure, which facilitates the rapid diffusion of gas on the surface of the sensitive material; on the other hand, the P type four oxidation three cobalt modifies the N type Zinc Oxide to form a p-n junction, which can significantly improve the gas sensitivity of the material. (2) explore the use of static electricity. The spray deposition technique uses a one-step synthesis strategy to direct the preparation of layered nickel oxide (NiO) / reduced graphene oxide (rGO) nanocomposites on a concentrated fluid. We use a mixed solution of nickel acetate / graphene oxide as precursor, and the composite materials are deposited directly on the fluid by electrostatic spray deposition in the process of deposition. By heating the collector to decompose nickel acetate and reducing the graphene oxide, the thin film electrodes deposited on layers of NiO/rGO nanocomposites have been prepared. In the electrochemical test, the NiO/rGO composite exhibits high specific capacitance and good cycling performance. We avoid using non conductive adhesives in the preparation of the electrodes. Most of the active materials maintain good electrochemical activity. (3) explore the use of electrostatic spray deposition technology and use the two step synthesis strategy to prepare the Mn_3O_4/rGO flexible electrode. First, the reduction Potassium Permanganate method is used to prepare the small ball assembled by the Mn_3O_4 tablet. Then, the mixture of Mn_3O_4 and GO is used as a precursor, and the electrostatic spray deposition is used. The product technology deposited the composite directly on the carbon cloth. Under the heating condition, the graphene oxide was reduced to rGO.. We compared the electrochemical performance of the flexible electrode (GM) prepared by the traditional coating method (CG) and the electrostatic spray deposition method. It was found that the capacity of the GM and the cyclic stability were better than the CG. in the GM electrode and the active material. The contact with the collector is stronger and has a certain toughness, and the active material can still be fully contacted with the fluid in the time of repeated bending. While the CG electrode is bent, the active material is broken and shedding, resulting in the loss of capacity. (4) we explore the use of electrostatic spray technology to prepare the reduced graphite oxide nano composite. Using the two step synthesis strategy, the Ni_3S_2 particles with the diameter of 10 nm of the Ni_3S_2/rGO. diameter of the bacterial intercalation are evenly distributed on the rGO layer. As a carrier, rGO can effectively prevent the aggregation of small Ni_3S_2 particles together, and on the other hand, it can provide 3 dimensional conductive network for the small particles of Ni_3S_2; and the bacteria are placed in the bacteria. The rGO layer can effectively improve the contact between the active material and the electrolyte and the diffusion of the ions between the active material and the electrolyte. We directly deposited the active material on the fluid collector, which can improve the contact between the active material and the fluid, reduce the contact resistance, and avoid the use of non conductive adhesives to make most of the Ni_3S_2 small. The particles maintain good electrochemical activity.

【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB383.1;TB33

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