含钨化合物纳米结构的合成及光电化学性能研究

发布时间：2018-02-22 21:41

本文关键词： 含钨化合物纳米结构复合材料合成光电化学性质　出处：《中国地质大学(北京)》2017年博士论文　论文类型：学位论文

【摘要】：当今社会,环境污染和化石能源紧缺已经逐步成为人类需要解决的首要问题,发展新材料以缓解环境污染以及实现能源替代是实施可持续发展战略的关键。钨作为一种稀有金属材料,它的多种化合物(如氧化钨和硫化钨)由于自身独特的物理化学性能已经在光催化、电催化、锂离子电池、太阳能电池以及传感器方面取得了广泛的应用。但是影响这些含钨化合物的光催化及电化学等性能的因素很多,关键因素尚不明确。因此,探明材料组成、结构、形貌等对其性能的影响,进而制备出具有优异光电化学性能的含钨化合物纳米材料,在解决环境污染和能源危机方面具有十分重要的战略意义。本论文通过高温管式炉合成出多个系列的WO3-x纳微米棒、Z型C fiber@WO3-x核壳复合结构、WS2纳米片、C fiber@WS2纳米片核壳复合结构,并探索了影响这些纳米材料性能的主要因素。(1)以WO3和S的粉末作为原料,在真空管式炉中,950-1150°C条件下,制备出一系列不同形貌、不同氧空位含量的WO3-x纳微米棒,并在空气中500°C下退火制备得到了相应的WO3纳米结构,分别测试了所得WO3-x纳米结构和其退火样品的湿敏性能和光催化性能。发现氧缺陷能使氧化钨展现出独特的正湿敏特性;在光催化方面,氧缺陷的存在也增强了WO3-x对待催化降解有机染料亚甲基蓝和罗丹明B分子分子的吸附作用。(2)以PAN纤维和氧化钨粉末作为原料,在不同温度下,在管式炉中制备得到了一系列Z型C fiber@WO3-x(0≤x3)核壳复合纳米结构。将所制备的复合材料应用在光催化降解亚甲基蓝和罗丹明B时,都展现出了出色的光催化降解效果。相较于纯的WO3,这种复合结构性能提高的主要原因是,PAN裂解的C纤维以及连接C纤维和WO3-x的金属W连接层能够有效的传导光生电子,降低了光生电子和空穴的复合几率,进而提高了材料的光催化性能。(3)以WO3和S的粉末作为蒸发源,在镀W膜的硅片上、在不同温度下,分别制备得到了水平生长和竖直生长的WS2纳米片,并将其组装成锂离子电池,测试了电池的电化学性能。实验表明,三次充放电循环后,用竖直生长的WS2纳米片组装的电池的放电比容量仍达773 mAh/cm3,性能优于文献中以WS2纳米片粉末为电极材料的锂离子电池。但是,以水平生长的WS2纳米片为电极材料的锂离子电池却不具有任何循环充放电的性能,一次放电后就不能再充电了。水平生长和竖直生长的WS2纳米片组装的电池截然不同的电化学特性,可能是由于两种WS2纳米片对锂离子嵌入和脱嵌机制不同造成的。(4)硫化钨作为光催化剂由于光生电子和空穴易复合,所以光催化效果不好。为了改善这一点,本文以PAN和WO3为原料,在S蒸气中高温煅烧,一步法制备得到了C fiber@WS2纳米片核壳复合结构,并在模拟太阳光下对所制备的复合结构进行了光降解有机染料、去除Cr(VI)和杀灭大肠杆菌的实验。实验表明,这种复合材料的光催化效果相对纯的WS2而言有着大幅度的提高,并且具有优良的稳定性。这制备复合材料的方法具有适普、高效、成本低等优点,该方法是一种开拓高性能、低成本光催化剂的新途径。
[Abstract]:In today's society, environmental pollution and fossil energy shortage has gradually become the most important human issues that need to be solved in the development of new materials to reduce environmental pollution and realize energy substitution is the key to implement the strategy of sustainable development. As a kind of tungsten and rare metal materials, many of its compounds (such as tungsten oxide and tungsten sulfide) because of its unique the physical and chemical properties in photocatalysis, electrocatalysis, lithium ion battery, solar battery and sensors have been widely used. But many factors influence the tungsten compound photocatalytic and electrochemical properties, the key factor is not clear. Therefore, explore the material composition, structure, morphology and influence on its performance then, prepared nano materials containing tungsten compounds with excellent Photoelectrochemical Performance, has important strategic significance in solving the energy crisis and environmental pollution. This paper through the high temperature tube furnace to synthesize a series of WO3-x micron rods, Z type C fiber@WO3-x core shell composite structure, nano WS2, nano fiber@WS2 C core-shell composite structure, and explore the main factors influencing the performance of these nano materials. (1) using WO3 and S powder as raw material and in the vacuum tube furnace, 950-1150 degrees under the conditions of C, we prepared a series of different shape, different content of oxygen vacancies of WO3-x micron rods, and in the air at the temperature of 500 DEG C annealing prepared WO3 nano structure, the WO3-x nano structures and humidity sensitive properties and photocatalytic properties the annealing samples were tested. Results indicated that the oxygen defects can make the tungsten oxide show a unique positive humidity sensitive properties; in the field of photocatalysis, oxygen defects also enhanced the adsorption of WO3-x to catalytic degradation of methylene blue and Luo Danming B molecules. (2) to PAN and fiber Tungsten oxide powder as raw material, under different temperature in the tube furnace to prepare a series of Z C fiber@WO3-x (0 x3) core-shell composite nano structure. The application of preparation of composite materials in the photocatalytic degradation of methylene blue and Luo Danming B, are showing the effect of photocatalytic degradation excellent. Compared with pure WO3, the main reason for the increase of the performance of the composite structure is PAN, the cleavage of C fiber and metal fiber C W connection and WO3-x connection layer can effectively transfer the photogenerated electrons, reduces the recombination rate of photogenerated electrons and holes, thus improving the photocatalytic properties of materials (. 3) with WO3 and S powder as the source, the silicon coated W film, at different temperatures, were prepared by nano WS2 growth and vertical growth, which is assembled into the lithium ion battery, electrochemical properties of the battery test. The test results show that three charge Discharge cycles, discharge of WS2 nanosheets for cell growth than the vertical capacity is up to 773 mAh/cm3, the lithium ion battery with nano WS2 powder as the electrode material is better than the literature. However, the performance of nano WS2 to the level of growth for the lithium ion battery electrode material does not have any charge discharge cycle the time after discharge can not be charged. The electrochemical properties of WS2 nanosheets assembled cell growth and vertical growth of different levels, may be due to two kinds of nano WS2 on lithium ion intercalation and deintercalation mechanism caused by the different. (4) tungsten sulfide as photocatalyst because of photogenerated electrons and holes easily the composite, so the photocatalytic effect is not good. To improve this, this paper takes PAN and WO3 as raw materials, high temperature calcination in S vapor, one step prepared C nano fiber@WS2 core-shell structure, and the simulated sunlight The composite structure by the photodegradation of organic dye, removal of Cr (VI) and killing Escherichia coli. Experimental results show that has greatly improved the photocatalytic effect of this composite material is relatively pure WS2, and has good stability. The composite material preparation method has Supresoft high efficiency, low cost, and the method is a new way to develop high performance, low cost and light catalyst.

【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB383.1

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