氮掺杂碳材料负载Pd基电催化剂的合成及其醇氧化性能研究

发布时间：2018-04-13 01:11

本文选题：直接醇类燃料电池 + Pd基纳米催化剂　；参考：《河南师范大学》2015年硕士论文

【摘要】：燃料电池是一种适应未来能源和环境要求的理想电源,目前已经在交通工具、手机电源等行业示范性应用,并受到了越来越广泛的关注。然而新型燃料电池催化剂铂的昂贵价格是制约其产业化的主要障碍之一,因此,探讨如何降低催化剂的成本、提高催化剂的活性是该领域目前的研究热点。这就需要从以下两方面入手:第一,对催化剂金属进行微观结构和表面性质上的优化,提高其催化活性。第二,构筑高性能的催化剂载体,它不仅直接影响催化剂的粒径、分散度、活性及稳定性,而且影响催化层的导电性、传质及电化学比表面积等。本论文旨在以开发利用氮掺杂碳材料载体入手,着重研究载体的表面结构,以便改善载体表面化学惰性,并且设计合成不同微观结构的Pd基纳米晶,使其均匀地负载在载体表面,以提高催化剂的催化活性和利用率,为提高直接醇类燃料电池阳极催化剂的性能提供理论依据。本文分别合成了氮掺杂碳纳米管、氮掺杂石墨烯、钴氮共掺杂碳的空壳结构三类系列变化的氮掺杂碳材料,并以其为主要载体,在其表面设计合成不同微观结构的Pd基纳米晶,分别研究了不同载体对钯纳米晶的形貌、粒径以及电催化性能的影响,并探讨了其影响规律。本论文的主要内容有以下几个方面:一、概述了燃料电池的研究现状、电极催化剂以及催化剂载体的研究进展,阐述了当前燃料电池催化剂研究存在的问题、本文的研究目的及研究内容。二、以聚吡咯作为氮源对碳纳米管进行氮掺杂,改变了碳纳米管表面的惰性状态,使得贵金属催化剂颗粒可以在其表面均匀附着,并通过一步水热法合成了氮掺杂碳纳米管复合钯铜合金纳米空壳催化剂,提高了Pd的利用效率,改善了其催化活性。结果表明,氮原子已成功掺杂于碳纳米管表面,氮掺杂类型以吡啶型和石墨型为主,并且合成的钯铜合金纳米空壳结构具有良好的分散性,其平均直径大约是50 nm。电化学测试表明氮掺杂碳纳米管负载钯铜合金纳米立方空壳催化剂对不同醇类电氧化均表现出良好的催化活性及稳定性。三、分别使用三聚氰胺,聚吡咯和聚苯胺作为氮源合成了一系列的氮掺杂石墨烯,并通过一步无模板法合成了氮掺杂石墨烯负载钯铜合金纳米立方空壳催化剂。不同的氮源提供了不同的氮掺杂特征,并对不同的氮掺杂类型(吡啶型N,吡咯型N和石墨型N)对钯铜合金纳米立方空壳催化剂结构形貌及电性能的影响进行了系统研究。结果表明所制备的钯铜合金纳米立方空壳(直径约50 nm)负载于氮掺杂石墨烯上分散性良好,并且氮元素在石墨烯载体上的分布也很均匀。电化学表征显示氮掺杂石墨烯负载钯铜合金纳米立方空壳催化剂对醇氧化具有卓越的催化活性与稳定性。四、以乙二胺四乙酸(EDTA)和三聚氰胺为氮源合成了氮掺杂石墨烯,并以此为载体采用原位还原法制备了Pt修饰的Pd Cu合金复合催化剂。结果表明,所合成的氮掺杂石墨烯具有较大的比表面积,与催化剂颗粒产生较大的接触面积,具有更强的载体-金属相互作用,Pt修饰的Pd Cu合金上,Pt原子大量沉积在催化剂表面,可以有效地提高催化剂活性。电化学性质测试表明,该催化剂显示出较好的催化活性和稳定性。五、以三聚氰胺做氮源,甲醛为碳源,乙酸钴为金属前驱体,通过无模板法实现了具有蛋黄-蛋壳结构特征的钴氮共掺杂碳材料(Co-N-CMs)的可控合成,并以此为载体负载Pd催化剂。结果表明,所合成的钴氮共掺杂碳材料具有较大的比表面积,可使担载金属纳米晶具有良好的分散性,并显示出较强的协同催化效应。
[Abstract]:Fuel cell is an ideal source of energy and environment to adapt to the requirements of the future, at present already in transportation, power and other industries mobile phone application, and has attracted more and more attention. However, the expensive new catalyst platinum fuel cell is one of the major obstacles to its industrialization so, discusses how to reduce the catalyst the cost, increase the activity of the catalyst is the current research hotspot in the field. This requires from the following two aspects: first, optimize the microstructure and surface properties of the metal catalyst, improve its catalytic activity. Second, to build a high performance catalyst carrier, which not only affects the catalyst particle size, dispersion the activity and stability, but also, affect the conductivity of the catalytic layer, mass transfer and electrochemical surface area. This thesis aims to the development and utilization of nitrogen doped carbon materials with the carrier, focusing on The surface of the carrier structure, so as to improve the chemical inert carrier surface, and the design and synthesis of different microstructures of Pd based nanocrystalline, which are uniformly loaded on the surface of the carrier, in order to improve the catalytic activity of the catalyst and utilization, provide a theoretical basis for improving the performance of the anode catalyst of direct methanol fuel cell. This paper studied the synthesis of nitrogen doped carbon nanotubes, nitrogen doped graphene, nitrogen doped carbon materials of shell structure of cobalt and nitrogen Co doped carbon three series of changes, which is the main carrier of the synthesis of different microstructure of nanocrystalline Pd based design on the surface of different carrier palladium nanocrystals were studied in morphology, particle size and catalytic performance the effect, and discusses its influence. The main contents of this paper are the following aspects: first, summarizes the research status of fuel cell, electrode catalyst and research progress of catalyst carrier, The paper discusses the existing problems of fuel cell catalysts, the research goal and the research content of this paper. Two, with polypyrrole as nitrogen source on nitrogen doped carbon nanotubes, changed the inert state on the surface of the carbon nanotube, the noble metal catalyst particles can be attached on the surface of uniform, and through a one-step hydrothermal synthesis of nitrogen doped carbon nanotube composite palladium copper alloy shell nano catalyst, improve the utilization efficiency of Pd and improve its catalytic activity. The results showed that the nitrogen atom has been successfully doped into the surface of carbon nanotubes, nitrogen doped type with pyridine type and graphite, and the synthesis of palladium copper alloy shell nano structure has good dispersion, the the average diameter is about 50 nm. electrochemical tests showed that the nitrogen doped carbon nanotubes supported palladium copper alloy nano cubic shell catalyst on different alcohols electrooxidation showed good catalytic The activity and stability. Three, respectively, the use of melamine, polypyrrole and polyaniline as a nitrogen source for the synthesis of nitrogen doped graphene series, and through a one-step template free nitrogen doped graphene supported palladium copper alloy nano cubic shell catalyst synthesis. The nitrogen source with different nitrogen doped different characteristics, and the different the nitrogen doping type (pyridine type N, type N and type N graphite pyrrole) of palladium copper alloy nano cubic shell catalyst structure morphology and electrical properties were studied. The results show that the prepared palladium copper alloy nano cubic shell (diameter 50 nm) supported on nitrogen doped graphene dispersion well, and the distribution of nitrogen in the graphene on the carrier is very uniform. The electrochemical characterization of nitrogen doped graphene supported palladium copper alloy nano cubic shell catalyst has excellent catalytic activity and stability for methanol oxidation. Four, With ethylenediaminetetraacetic acid (EDTA) and melamine as nitrogen source for the synthesis of nitrogen doped graphene, and as the carrier by in situ Pd Cu alloy composite modified Pt catalyst prepared by reduction method. The results showed that the synthesis of nitrogen doped graphene has a larger surface area, have larger contact area with the catalyst particles, with stronger carrier metal interaction, Pd Cu alloy modified by Pt, Pt atoms deposited on the catalyst surface, can effectively improve the catalyst activity. The electrochemical characterization showed that the catalyst showed good catalytic activity and stability. Five, using melamine as nitrogen source, formaldehyde as carbon source for metal cobalt acetate the precursor cobalt nitrogen by template free method is realized with the yolk shell structure of Co doped carbon materials (Co-N-CMs) controlled synthesis, and as a supported Pd catalyst. The results show that the Institute The cobalt and nitrogen Co doped carbon materials have larger specific surface area, which can make the supported metal nanocrystals have good dispersion and exhibit strong synergistic catalytic effect.

【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TM911.4

【共引文献】