摘 要

为了应对化石能源短缺，大气污染等问题，当前世界各国都在努力寻找化石能源的替代资源。为了响应国家号召，减少化石能源的使用，汽车行业近年来也在努力开发新能源汽车。其中，燃料电池由于经济性好，清洁高效等优势更是早在19世纪就被人们发现并研究。燃料电池通过将燃料具有的化学能直接转变为电能，中间不经过燃烧过程，因此不受卡诺循环的限制能量转换效率高，除此，它的燃料和氧化剂不直接存储在电池内，发电时不断地从外部的储罐向电池内输送燃料和氧化剂，燃料电池本身只决定输出功率的大小。然而，由于燃料电池价格昂贵，使用寿命较短，近年来一直未能得到广泛使用。其中主要原因还是其使用贵金属铂作为催化剂价格昂贵，而贵金属Pt在燃料电池中可以提高反应电催化速率，降低反应所需活化能，在燃料电池中起着至关重要的作用。

在此我们通过将Pt制作成为介孔结构来提高Pt的比表面积，提高Pt利用率，减少Pt的用量，从而降低成本。这里我们使用PS-PVP-PEO三嵌段共聚物作为模板，通过软模板法合成介孔Pt，并结合SEM，XRD等表征测试方法对材料进行表征，最后通过电化学工作站，进行甲醇氧化电催化试验，验证所得样品的催化效率，与工业铂黑进行比较。

关键词：燃料电池；介孔材料；软模板法；催化剂

Abstract

In order to solve the problems of fossil energy shortages and air pollutions, now countries around the world are struggling to find alternative sources of fossil fuels. In response to the national calls to reduce the use of fossil fuels, in recent years the automotive industry is also trying to develop new energy vehicles. Among them, the fuel cell because of good economy, cleaning and efficiency and other advantages as early as the 19th century was found and studied. The chemical energy of the fuel can be directly converted into electrical energy by fuel cell, and it doesn’t go through the combustion process, so it won’t be restricted by Carnot cycle, its energy conversion efficiency is much higher. In addition, the energy and oxidants of fuel cell are not directly stored in the battery, the fuel and oxidants are transmitted from the external tank when generating, the fuel cell itself only determines the size of the output power. However, since fuel cells are expensive and have a short service life, they have not been widely used in recent years. The main reason is that the use of precious metal platinum as a catalyst is expensive, and precious metal Pt in the fuel cell can improve the reaction rate of electrocatalysis and reduce the activation energy required for the reaction, plays an important role in the fuel cell.

In this paper, we synthesized mesoporous Pt to improve the specific surface area of Pt, and improve the utilization of Pt, reduce the amount of Pt in the fuel cell, thereby, the cost of the fuel cell can be reduced. Here, we used PS-PVP-PEO triblock copolymer as template, and the mesoporous Pt was synthesized by soft template method. The materials were characterized by SEM and XRD. Finally, performing electrochemical measurement through electrochemical analyzer, to verify the catalytic efficiency of the obtained sample, compared with the commercial platinum black.

Keywords: Fuel cell; Mesoporous structure; Soft templating method; Catalyst

Contents

摘要 I

Abstract II

1 Introduction 1

2 The application of the fuel cell in vehicles 3

2.1 The application of the fuel cell vehicles 3

2.2 Fuelled EVs 11

3 Fuel Cell 12

3.1 The development of fuel cell 12

3.2 Classification of fuel cell 13

3.3 Advantages and disadvantages of fuel cells 14

3.4 The principle and application of Proton Exchange Membrane Fuel Cell 15

4 Experimental section of synthesis of mesoporous Pt 23

4.1 The catalyst of fuel cell 23

4.1.1 Non-noble metals catalyst 23

4.1.2 Noble metal catalyst 27

4.2 The catalysis action of Pt in fuel cell 30

4.3 Preparation of mesoporous Pt 33

4.3.1 Hard template method 33

4.3.2 Soft template method 36

4.3.3 The classification of micelle particles 42

4.4 Experimental chemicals 43

4.5 Synthesis of mesoporous Pt 44

5 Results and discussion 45

6 Summary and expectation 52

6.1 Summary 52

6.2 Expectation 53

References 53

Acknowledgements 56

1 Introduction

With the second industrial revolution, the internal combustion engine has been widely used, mankind also entered the electrical age. The invention of automobiles and airplanes has also become a great achievement for the second industrial revolution. However, with the continuous growth of population and the development of industrialization, human demand for energy is increasing. With the aggressive exploitation of people, there are studies that coal, oil, natural gas and other non-renewable resources will be disappeared in the next few decades to hundreds of years ^[1]. At the same time, along with the burning of fossil fuels, air pollution has become a problem that cannot be ignored in the current society. The exhaust gas emitted by the vehicle in the course of running contains toxic and hazardous substances such as carbon monoxide, nitrogen oxides, hydrocarbons, sulfur oxides and lead compounds. Therefore, it is urgent to find out environmentally friendly alternative resources of fossil fuels.

In the automotive industry, the major automobile manufacturers and research institutes concentrate to develop non-conventional vehicle fuel as a power source of new energy vehicles in recent years ^[2]. The vehicle fuel will directly affect the economy, power and emission performance of the car. The car manufacturers are committed to looking for new non-polluting, renewable clean energy, such as methanol, ethanol, hydrogen, etc. The current new energy vehicles, including pure electric vehicles, hybrid vehicles, fuel cell vehicles and solar cars, etc. Among them, the fuel cell(FC) was found and studied as early as nineteenth century, as a result of the economy is good, clean and efficient. The chemical energy of fuel directly transformed into electricity by FC, instead of conversion through the combustion process, therefore, it has a higher energy conversion efficiency without the limit of Kano cycle. The fuel and oxidant are not directly stored in the battery, which continuously delivered from external tank to the battery, and the fuel cell itself only determines the magnitude of the output power.

The concept of molten carbonated fuel cell (MCFC) was first proposed in the 1940s, and the MCFC, which was pressurized in the 1980s, began to run, and it is expected that the MCFC will achieve semi-commercialization in this century. The working temperature of the MCFC is 600 ~ 700, the use of high value of waste heat, electrocatalyst without the use of precious metals, available desulfurization gas to do fuel ^[3].

To solve the problems of energy shortage and atmospheric pollution, vigorously promoting the development and application of new energy vehicles. The current new energy vehicles include pure electric vehicles, hybrid cars, fuel cell vehicles and solar cars, etc. Among them, the fuel cell vehicle because of good economy, clean and efficient and other advantages as early as the 19th century was found and studied. The fuel cell directly converts the chemical energy of the fuel into electrical energy and does not pass through the combustion process. Therefore, it is not limited by the Carnot cycle, and the energy conversion efficiency is high. The energy and the oxidant are not directly stored in the battery, but transferred from the external tank to fuel cell, and the fuel cell itself only determines the magnitude of the output power. However, because the fuel cell is expensive, life time is rather short, it has not been extensively applied in recent years. The main reason is that it is expensive to use noble metals as a catalyst, and noble metal Pt can improve the rate of catalytic reaction, reduce the activation energy required for the reaction, which is of vital importance in the fuel cell, however, its high price prevent the market promotion of fuel cell. Therefore, in order to enhance the catalytic performance of the catalyst, the surface of Pt catalyst can be modified by other atoms, or using alloys as catalyst, besides, it can improve the surface area of catalyst by synthesis mesoporous Pt.

Because of the unique construction and excellent performance of highly ordered mesoporous materials, and the speculated applications of separation and purification, chemical industries, catalysts, information communication, environment, source of energy, and the new assembly materials, it has attracted extensive researches. Comparing with other methods, templating method has the characteristic of simplicity of operator, high productive efficiency, and good reproducibility. Besides when it comes to the kind of particles and the control of surface properties, templating method is much better than other approaches. Among them, lyotropic liquid crystals (LLCs), which is a typical soft-templating method, have a variety of structure forms, such as lamellar, hexagonal, cubic and so on. The functional materials with highly ordered structures and the physical structure easy to control and later process can be prepared by adjusting the phase structure of template, species of particles, surface properties, and regulation the interaction between particles and the interaction between films. Therefore, it is of great importance to synthesize nanomaterials with special morphology prepared by LLCs.