多孔及二维无机材料的复合和其催化、电化学性能的研究

发布时间：2018-06-20 06:49

本文选题：无机复合材料 + 微孔分子筛　；参考：《上海交通大学》2014年博士论文

【摘要】：无机复合材料是一类重要的功能材料，是由不同组分在微纳尺度或者分子水平上复合或者组装所形成的一类新材料。通过复合，各组分在性能互补的基础上，可以产生协同效应，从而赋予无机复合材料独特的性质。多孔和二维无机复合材料因其独特的结构特点，已广泛的应用于人类生活的各个领域，如石油加工、汽车和航空等工业领域。然而，随着能源和环境问题日益突出，人们迫切需要开发具有更高性能的新型多孔和二维无机复合材料，比如在催化领域，开发新型汽车尾气净化催化剂，有效提高催化活性，降低贵金属的消耗；在电化学储锂领域，开发出容量高、循环稳定性好和倍率性能优异的新型锂离子电池材料，满足电动汽车对高能量密度和高功率密度锂离子电池的需求。因此，开发新型多孔和二维无机复合材料，探索其复合结构以及协同作用对其应用性能的影响，具有重要的理论和实际意义。本论文以功能为导向，设计合成了一系列具有独特结构和优异性能的新型多孔和二维无机复合材料，探究了其复合结构制备中的关键问题，考查了其电化学储锂和催化等性能，研究了复合结构与性能之间关系。具体内容包括： (1)贵金属/微孔分子筛复合材料的制备及其催化性能研究通过改进浸渍法制备了贵金属铂与SAPO-44型磷酸硅铝分子筛复合的无机材料(Pt/SAPO-44)，利用X射线吸收光谱、透射电镜和程序升温还原技术考察了分子筛负载贵金属铂的价态及尺寸，发现贵金属铂在空气中以纳米铂簇的形式负载到SAPO-44分子筛上，铂簇的粒径在2-4nm之间。考察了Pt/SAPO-44复合材料在汽车尾气净化中的应用，研究发现SAPO-44分子筛骨架表面Br nsted酸与铂纳米粒子之间存在强烈的协同催化作用，有效提高了催化剂的尾气净化性能，大大减少了贵金属铂的用量。 (2)新型graphene/MoS2异质复合薄膜材料的制备及其电化学性能研究以氯化钼与油酸钠反应生成的油酸钼为碳源和钼源，通过热处理在硫酸钠晶体表面合成了graphene/MoS2异质复合薄膜材料，结构表征发现，复合薄膜由硫化钼层和石墨烯层复合而成，且表面平整、结构均一、具有较大的表面积（160μm）。在合成过程中，硫酸钠不仅提供硫源，，其晶体表面作为复合薄膜生长的基体。通过改变原料中氯化钼与油酸钠摩尔配比，可以调控复合薄膜中硫化钼的层数。Graphene/MoS2复合薄膜材料表现出非常优异的电化学储锂性能，在高电流密度充放电情况下，依然具有非常高的电池容量和非常突出的循环稳定性。 (3)二氧化锡纳米晶/碳复合薄膜材料的的制备及其电化学性能研究以硫酸钠晶体为基体，油酸锡和氯化锡为碳源和锡源，通过一步热处理合成了二氧化锡纳米晶/碳复合薄膜材料。结构表征发现，二氧化锡纳米晶尺寸均一，平均晶粒直径为2-3nm，均匀分散在石墨化的碳薄膜中。二氧化锡纳米晶/碳复合薄膜材料表现出非常优异的电化学储锂性能，在恒定电流密度0.5、1.0和10.0A g-1下循环50圈后，其可逆容量分别高达826、728和400mAhg-1。二氧化锡纳米晶/碳复合薄膜材料的优异电化学性能得益于其独特的复合结构。氧化锡纳米晶，可以有效的缩短锂离子的扩散距离；石墨化的碳薄膜，不仅可以改善材料的导电性，还可以极大缓冲充放电过程中纳米晶体积变化对复合薄膜材料结构稳定性的影响；此外，石墨化碳薄膜的有效包覆，可以避免电解液与氧化锡纳米晶的直接接触，防止电解液在高活性纳米晶表面的分解等不利反应，从而改善材料的循环稳定性。
[Abstract]:Inorganic composite is a kind of important functional material, which is a kind of new material formed by the composite or assembly of different components at the microscale or molecular level. By composite, the synergistic effect can be produced on the basis of the performance complementation, which gives the unique properties of the inorganic compound material. Porous and two-dimensional inorganic compound. Because of its unique structural characteristics, materials have been widely used in various fields of human life, such as petroleum processing, automobile and aviation industries. However, with the increasingly prominent energy and environment problems, people urgently need to develop new porous and two-dimensional inorganic composite materials with higher performance, such as the development of new type of steam in the field of catalysis. The catalyst of vehicle exhaust purification can effectively improve the catalytic activity and reduce the consumption of precious metals. In the field of electrochemical lithium storage, a new type of lithium ion battery material with high capacity, good circulation stability and excellent multiplying performance is developed to meet the demand for high energy density and high power density lithium ion batteries for electric vehicles. In this paper, a series of new porous and two-dimensional inorganic complex materials with unique structures and excellent properties are designed and synthesized in this paper, and the key to the preparation of composite structures is explored. The electrochemical lithium storage and catalytic properties were investigated, and the relationship between the composite structure and properties was studied.
(1) preparation and catalytic properties of noble metal / microporous molecular sieve composites
Inorganic materials (Pt/SAPO-44) of noble metal platinum and SAPO-44 type Si Al molecular sieve were prepared by improved impregnation method. The valence state and size of noble metal platinum supported by molecular sieves were investigated by X ray absorption spectrum, transmission electron microscope and temperature programmed reduction technology. It was found that precious metal platinum was loaded to SAPO-4 in the form of nano platinum cluster in the air. On the 4 molecular sieve, the particle size of the platinum cluster is between 2-4nm. The application of Pt/SAPO-44 composite in the purification of automobile exhaust is investigated. It is found that there is a strong synergistic catalysis between Br nsted Acid and platinum nanoparticles on the skeleton surface of the SAPO-44 molecular sieve, which can effectively improve the purification performance of the catalyst, and greatly reduce the use of precious metal platinum. Quantity.
(2) the preparation and electrochemical properties of a new graphene/MoS2 heterostructure composite film material. Molybdenum oleate was produced by molybdenum chloride and sodium oleate as carbon source and molybdenum source. Graphene/MoS2 heterostructure composite film was synthesized by heat treatment on the surface of sodium sulfate crystal. The structure characterization found that the composite film was reproduced by molybdenum sulfide layer and graphene layer. In the process of synthesis, sodium sulfate not only provides sulfur source, but its crystal surface is the substrate for the growth of the composite film. By changing the molar ratio of molybdenum chloride to sodium oleate in the raw material, the layer number of molybdenum sulfide in the composite film can be controlled in the synthesis process, and the number of layers of.Graphene/MoS2 composite films in the compound film can be regulated in the synthesis process. The material exhibits excellent electrochemical lithium storage performance. Under the condition of high current density charge and discharge, it still has very high battery capacity and very prominent circulation stability.
(3) the preparation and electrochemical properties of two tin oxide nanocrystalline / carbon composite film materials, with sodium oleate as the matrix, tin oleate and tin chloride as carbon source and tin source, two Sn nanocrystalline / carbon composite films were synthesized by one step heat treatment. The structure characterization found that the size of two tin oxide nanocrystals was uniform, and the average grain diameter was found. 2-3nm, uniformly dispersed in graphitized carbon films, two tin oxide nanocrystalline / carbon composite films exhibit excellent electrochemical lithium storage properties. The reversible capacity is up to 826728 and 400mAhg-1. two tin nanocrystalline / carbon composite films, respectively, after a constant current density of 0.5,1.0 and 10.0A g-1. The chemical properties benefit from its unique composite structure. The tin oxide nanocrystals can effectively shorten the diffusion distance of the lithium ion. The graphitized carbon film can not only improve the conductivity of the material, but also greatly buffer the influence of the change of the volume of nanocrystalline on the structural stability of the composite film during the charge discharge process; in addition, graphite carbon The effective coating of the film can avoid the direct contact between the electrolyte and the nanocrystalline oxide, prevent the disadvantageous reaction of the electrolyte on the surface of the highly active nanocrystalline, and thus improve the cyclic stability of the material.
【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TB33;TM912

【参考文献】