缺陷氧化钨纳米复合材料的制备、表征及其应用研究

发布时间：2018-04-29 00:29

本文选题：氧化钨 + 复合材料　；参考：《西北农林科技大学》2017年硕士论文

【摘要】：氧化钨(WO_3)作为一种重要的n型半导体材料,由于其具有特殊的缺陷结构和物理化学特性被广泛地应用到气体传感、光催化、电致变色和场致发射等领域。实际制备中存在一些非化学计量比的氧化钨(WO_(3-x))由于其晶体中存在一定量的氧空位缺陷,可以在一定程度上提高导电率、减小能带隙,而且还能增强氧化钨表面对物质(如CO2、H2、NO2)的吸附,为催化反应提供更多的活性位点,所以在光催化剂和电极材料等方面具有重要的研究和应用价值。因此,本文主要针对缺陷氧化钨及其复合物的制备,对他们在催化反应和锂离子电池方面的应用进行了深入的研究。本论文的主要研究内容及取得的成果如下:(1)以钨酸铵和柠檬酸为原料,利用柠檬酸的还原能力及形貌控制作用,一锅水热法成功的合成了具有大量缺陷存在的氧化钨纳米线。通过与商品氧化钨的对比,发现缺陷氧化钨具有更窄的禁带宽度,而且在可见光和近红外区有着更强烈的光吸收,呈现出新的光学特性和应用。(2)利用缺陷氧化钨能提供自由电子的特性,在合成过程中不加入稳定剂、助还原剂等,在室温条件下通过原位还原的方法直接将Pd2+还原成Pd纳米颗粒,并负载在缺陷氧化钨表面。将此催化剂用于对硝基苯酚加氢反应以及苯乙烯加氢反应中,表现出了优异的催化性能。(3)通过化学聚合以及高温碳化的方法成功制备出N-C包覆的缺陷氧化钨WO_(3-x)/N-C的复合材料,然后将其作为锂离子电池负极材料研究了缺陷氧化钨及其复合材料的电化学性能。结果表明,WO_(3-x)/N-C复合材料比缺陷氧化钨纳米线具有更加优异储锂能力和循环稳定性能。
[Abstract]:As an important n-type semiconductor material, WO _ 3 (W _ 2O _ 3) has been widely used in gas sensing, photocatalysis, electrochromic and field emission due to its special defect structure and physical and chemical properties. There are some non-stoichiometric tungsten oxide WO _ 2O _ 3-xC) because of the oxygen vacancy defects in the crystal, the conductivity can be improved and the energy band gap can be reduced to a certain extent. It can also enhance the adsorption of materials (such as CO _ 2H _ 2H _ 2O _ 2) on the surface of tungsten oxide, and provide more active sites for catalytic reaction, so it has important research and application value in photocatalyst and electrode materials. Therefore, in this paper, the preparation of defective tungsten oxide and its complexes, their applications in catalytic reactions and lithium ion batteries were studied. The main contents and achievements of this thesis are as follows: (1) with ammonium tungstate and citric acid as raw materials, tungsten oxide nanowires with a large number of defects have been successfully synthesized by one pot hydrothermal method using citric acid reduction ability and morphology control effect. Compared with commercial tungsten oxide, it is found that the defect tungsten oxide has narrower band gap and stronger light absorption in the visible and near infrared region. It shows new optical properties and applications. (2) using defective tungsten oxide to provide free electrons, no stabilizer and reductant are added in the synthesis process. Pd2 was directly reduced to PD nanoparticles by in-situ reduction at room temperature and loaded on the surface of defective tungsten oxide. The catalyst showed excellent catalytic performance in hydrogenation of p-nitrophenol and hydrogenation of styrene. The N-C-coated composite of defective tungsten oxide (WO_(3-x)/N-C) was successfully prepared by chemical polymerization and high temperature carbonization. The electrochemical properties of defective tungsten oxide and its composites were studied as anode materials for lithium ion batteries. The results show that WO _ 2 / 3-x / N-C composites have better lithium storage capacity and cyclic stability than defective tungsten oxide nanowires.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ136.13;TB383.1

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