非铂类高效氧还原催化剂设计及性能研究

发布时间：2018-03-04 15:20

本文选题：氧还原反应　切入点：催化剂　出处：《中国科学院大学(中国科学院过程工程研究所)》2017年博士论文　论文类型：学位论文

【摘要】：当今社会,由化石能源过度消耗引起的能源危机、环境污染问题日益突出,制约着社会的进步、危害人们的身体健康。因此,开发新型绿色能源技术已是迫在眉睫。燃料电池可以通过正负极的氧化还原反应将储存在化学物质中的化学能直接转化为电能,产物只有水。这种能量转换技术转换效率高、绿色环保、构造简单、稳定性好、启动快,近些年掀起了研究热潮,成为继化石能源后又一重要的能源利用形式。然而,燃料电池内部阴极的氧气还原反应(ORR)动力学过程比阳极反应慢,大大降低了电池的输出电压。为提高阴极反应速率,常用的传统催化剂为铂(Pt)。但是铂价格昂贵,稳定性差,严重制约了燃料电池的大规模商业化发展。因此研发廉价、高效的燃料电池阴极ORR催化剂是推动燃料电池发展产业的重要研究课题之一。本论文主要通过掺杂碳材料和复合多金属氧酸盐(多酸,POMs)两种方法制备非Pt的非贵金属和无金属的ORR催化剂,并研究了材料在不同pH条件下催化氧还原的性能。取得以下研究成果:(1)通过对石墨炔进行杂原子掺杂处理,研发了一种新型、无金属、掺杂石墨炔的二维碳材料。对石墨炔进行N、B、S、F单原子和NS、NB、NF双原子的掺杂,制备了掺杂材料,并在碱性条件下分别对其进行半电池和全电池性能测试,发现NF共掺的材料的半电池及全电池测试性能均优于其它材料。并且材料在稳定性、抗甲醇干扰性、抗CO中毒性能等方面都优于Pt/C。密度泛函理论(DFT)计算从机理角度解释了掺杂效应。实验表明掺杂石墨炔是一种廉价、稳定、高效的非金属催化剂。(2)开发了一种自下而上设计合成催化剂的方法。以对二氰基苯为单体,在实验指导下自下而上的通过不同反应温度、不同反应时长及不同元素掺杂处理等条件制备结构可控的三维多孔碳材料(PTF),并进行电化学测试以研究该材料在碱性条件下的催化ORR性能。发现,随着温度升高,材料的导电性大幅度提升,催化效果显著;N的形态对材料催化ORR影响显著,石墨氮是活性最高的N形态;不同元素影响氧还原反应不同的反应参数:B有利于提高材料的选择性,F有利于提高起始电位和电流密度。通过这种自下而上的制备方法为氧还原反应机理的研究带来便利。在此工作的基础上还探索了通过引入Fe和I,制备适用于酸性介质中的ORR催化剂。发现Fe和I的掺杂顺序对材料性能影响明显,先掺Fe后掺I的PTF-Fe-I性能最好。(3)首次制备一种多金属氧酸盐和碳材料复合的非贵金属多酸基复合材料,并用于催化中性和碱性条件下的氧还原反应。借助多酸和碳材料强相互作用力,简单一步法制备了复合材料。将该材料用于中性及碱性介质中测试,发现材料出现4e-催化反应区,研究了多酸基催化剂催化ORR的反应机理。该工作对于指导多酸在燃料电池中的应用提供了借鉴意义。(4)开发了一种将含有不同3d金属的多酸和不同的碳基底材料复合的简单方法。将制备的材料用于中性及碱性条件氧还原催化,研究了不同的3d金属(Cu,Co,Ni)和不同的碳基底材料(Vulcan XC-72,石墨烯,有机碳材料)对材料性能的影响。探索制备高效多酸基复合催化剂的多酸活性位点和优秀的碳材料的条件。
[Abstract]:In today's society, the excessive consumption of energy caused by fossil energy crisis, environmental pollution problems have become increasingly prominent, which restricts the progress of society, endanger people's health. Therefore, the development of new green energy technology is imminent. The fuel cell can be stored in chemicals in the chemical energy directly into electrical energy through the anode oxidation the reduction reaction product is only water. This energy conversion technology of high conversion efficiency, green environmental protection, simple structure, good stability, quick start, has been a hot research topic in recent years, becoming an important fossil energy use energy form. However, inside the fuel cell cathode oxygen reduction reaction (ORR) than the anodic reaction kinetics slowly, greatly reduces the output voltage of the battery. In order to improve the cathodic reaction rate, the traditional catalyst used for platinum platinum (Pt). But the price is expensive, poor stability, serious constraints The large-scale commercial development of the fuel cell. So the development of low-cost, efficient ORR fuel cell cathode catalyst is one of the important research topics to promote fuel cell industry development. This paper mainly by doping carbon materials and composite polyoxometalates (POM, POMs) two were prepared by non Pt and non noble metal no metal ORR catalyst, and to study the catalytic properties of materials under different pH conditions of oxygen reduction. The research results are as follows: (1) the graphdiyne of heteroatom doping treatment, developed a new, no metal, two dimensional carbon materials doped Shi Moque. N, B of graphdiyne, S F, single atoms and NS, NB, NF atoms doped, doped materials were prepared, and under alkaline conditions of the half cell and battery performance testing, found that half cell NF Co doped materials and the battery test performance is superior to other materials. And the material in the stability, anti methanol interference, anti CO poisoning performance are better than the Pt/C. density functional theory (DFT) calculation explains the doping effect mechanism from the point of view. The results showed that the graphite alkyne is a cheap, stable, non metal catalyst with high efficiency. (2) developed a bottom-up design synthesis catalyst. To two cyanobenzene as monomer in the experiment under the guidance of bottom-up by different reaction temperature, porous carbon materials with different reaction time and different doping processing conditions for preparing controllable structure (PTF), and to study the electrochemical catalytic performance of the ORR material under alkaline conditions. With the increase of temperature, conductivity, greatly enhance the material, the catalytic effect is significant; effects of N on morphology of ORR catalytic material significantly, graphite nitrogen is the highest activity of N form; different elements influence oxygen reduction reaction The same reaction parameters: B can improve the material selectivity of F can improve the initial potential and current density. For the convenience of the oxygen reduction reaction mechanism through a bottom-up preparation method. On the basis of the above work is explored through the introduction of Fe and I, is suitable for the preparation of ORR catalysts in acidic medium found. Effects of Fe and I doping on the properties of the material was first order, the performance of PTF-Fe-I doped I doped Fe (3) for the first time. The best preparation for polyoxometalates and carbon composite non noble metal polyoxometalate based composite materials, and used to catalyze the neutral and alkaline conditions of oxygen reduction reaction. With the help of multi acid and strong interaction of carbon materials, composite materials were prepared in a simple step method. The materials used for testing of neutral and alkaline medium, found the material 4e- catalytic reaction zone, the reaction mechanism catalyzed by ORR acid based catalysts. Provide a reference for guiding the application of the work of Polyoxometalates in the fuel cell. (4) a simple method of multi acid and different carbon substrate composite materials developed a 3D containing different metals. The prepared materials for neutral and alkaline conditions of oxygen reduction catalyst, was studied with 3D metal (Cu, Co, Ni) and different carbon substrates (Vulcan XC-72, graphene, carbon material) on the properties of materials. Explore acid active site preparation, POMS composite catalyst and excellent carbon material conditions.

【学位授予单位】：中国科学院大学(中国科学院过程工程研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4

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