铂基燃料电池催化剂的可控合成与电催化性能的研究
发布时间：2018-09-18 09:59
【摘要】：使用量日益增长的化石能源在提高我们生活质量的同时,也带来了严重的环境污染,因此开发一种绿色能源是缓解目前环境危机的唯一途径。质子交换燃料电池作为一种新型能源,运行过程中不排放污染物,是理想的化石能源的替代品。但质子交换燃料电池的高效运行,依赖于价格昂贵的铂和基于铂的贵金属催化剂,这严重阻碍了质子交换燃料电池的大规模应用,因此,质子交换燃料电池研究中的主要内容就是提高铂的催化活性。大量研究证实,铂的催化性能严重依赖于表面结构。特别是高指数晶面,因其表面原子配位数低,而具有更高的催化活性。本文主要是在水-乙二醇这一简单体系中通过调节合成参数,开发出一系列具有高催化活性的燃料电池催化剂。本文主要在以下几个方面开展了研究： 1、铂多足分支纳米结构的可控合成与电催化性能的研究：纳米晶体的表面参数(特别是比表面积、表面原子分布情况)是影响纳米催化剂性能的重要因素,分枝结构的结构特征使其具有很好的催化性能,然而在实际合成中却很难实现分枝数目的可控性。在这个工作中,通过调控合成过程中加入的HCl量,实现了不同分枝数目的Pt纳米结构的可控合成。在这个反应中,HCl的氧化刻蚀在纳米晶的合成中起到三个方面的调控作用：(1)调控纳米晶和晶种的结晶度；(2)调控{111},{100}晶面的数量；(3)调控新生供给原子的浓度。因此,通过调控HCl刻蚀剂加入量的简单方法,可以实现三足、四足、六足和八足的Pt纳米分支结构的可控合成。这种可控合成的方法揭示了结构对于电催化性能影响的机理,测试显示铂八足纳米晶对甲酸氧化性能最优。本方法为复杂纳米机构的合成和性能的研究开辟了新的视野。 2、凹面立方铂-氧化石墨烯复合材料的可控合成与电催化性能的研究：当前在燃料电池中,纳米Pt催化剂用作氧化还原反应(ORR),但是同时实现稳定性和高活性仍然是个富有挑战性的工作。在本工作中,我们合成一种高度凹陷且具有高指数晶面的纳米立方块(HCC)。通过与石墨烯自组装形成复合催化剂可以显著提高Pt HCC的稳定性,同时体现出非常高的催化性能,比商业用的Pt/C催化剂的催化性能高了7倍。在催化剂使用量为46μgcm-2的情况下,半波电位(E1/2)仍然可以达到0.967V,比Pt/C高63mV,甚至优于文献最高纪录多孔纳米Pt-Ni。这个工作为基于惰性载体的贵金属纳米催化剂的催化性能调控开辟了新思路。 3、铂多足立方分支结构的镍离子辅助合成与电催化性能的研究：Pt(100)面通常被认为在氧还原反应(ORR)中活性较低。本论文报道的是一个独特的Pt多足立方分支纳米结构,其表面主要由{100}面构成,但在立方体之间连接部分具有少量高指数晶面。其合成过程是通过Ni2+为介质从多枝状结构的高指数{311}面转变到{100}面。尽管其表面由{100}面覆盖,铂多足立方体依然表现出较高的ORR活性,其半电位和电流密度与活性最高的铂镍合金催化剂的性能接近,而且该催化剂催化稳定性强。该表面演变实现了一种调节低指数晶面与高指数晶面比例的方式。本论文的结果表明,Pt多足立方分支结构的优异ORR性能是高指数晶面的高催化活性和低指数平整晶面与电极的低接触电阻相结合的结果。本论文提出一种晶面控制和ORR催化剂设计的新方法。 4、具有高指数晶面的铜铂合金的可控合成：Pt以其高效的催化性能而广泛应用在质子交换薄膜燃料电池中,但其昂贵的价格制约了燃料电池的进一步商业化推广,因此提高Pt的催化活性以降低成本显得意义重大。目前主要采用两种方式来提高Pt的催化性能：(1)Pt与其它金属M (M=Pd、Co、Ni、Fe、Au、 Cu)等形成基于Pt的合金；(2)在合成体系中加入表面保护剂,合成出具有高指数晶面的铂纳米晶。但这两种方法都存在着严重的不足,这也使得合金催化的研究尚不够成熟。本课题在结合前人研究的基础上开发出一种合成铜铂合金的新方法,为制备具有高效催化活性的合金开辟了新的视野。
[Abstract]:The increasing use of fossil energy not only improves the quality of our lives, but also brings serious environmental pollution. Therefore, developing a green energy is the only way to alleviate the current environmental crisis. However, the high efficiency of proton exchange fuel cell depends on expensive platinum and platinum-based precious metal catalysts, which seriously hinder the large-scale application of proton exchange fuel cell. Therefore, the main content of proton exchange fuel cell research is to improve the catalytic activity of platinum. In this paper, a series of fuel cell catalysts with high catalytic activity were developed by adjusting the synthesis parameters in the simple system of water-ethylene glycol.
1. Controlled synthesis and electrocatalytic properties of platinum multipedal branched nanostructures: Surface parameters (especially specific surface area, surface atom distribution) of nanocrystals are important factors affecting the performance of nanocatalysts. The structural characteristics of branched nanostructures make them have good catalytic performance, but it is difficult to separate them in practical synthesis. In this work, the controllable synthesis of PT nanostructures with different number of branches was achieved by controlling the amount of HCl added in the synthesis process. In this reaction, oxidation and etching of HCl play three roles in the synthesis of nanocrystals: (1) regulating the crystallinity of nanocrystals and seeds; (2) regulating {111}, {111}, { The number of 100} crystal planes; (3) the concentration of newly supplied atoms is regulated. Therefore, the tripod, quadruped, hexapod and Octopod PT nano-branching structures can be synthesized by controlling the amount of HCl etchant added. This controlled synthesis method reveals the mechanism of the effect of the structure on the electrocatalytic performance, and tests show that platinum Octopod nano-branching structures can be synthesized. This method opens up a new field of vision for the synthesis and properties of complex nanostructures.
2. Controlled synthesis and Electrocatalytic Performance of concave cubic platinum-graphene oxide composites: Nowadays, nano-Pt catalysts are used as redox reactions (ORR) in fuel cells, but achieving stability and high activity at the same time is still a challenging task. In this work, we synthesized a highly concave and high-finger composite. Nano-cubic block (HCC) with several crystal planes. The stability of Pt HCC can be significantly improved by self-assembly with graphene to form a composite catalyst, which exhibits very high catalytic performance. The catalytic performance of the composite catalyst is seven times higher than that of commercial Pt/C catalyst. V, 63 mV higher than Pt/C, and even better than the highest-recorded porous nano-Pt-Ni in the literature. This work opens up a new way to control the catalytic performance of noble metal nanocatalysts based on inert carriers.
3. Nickel ion-assisted synthesis and electrocatalytic properties of platinum polypod cubic branched structures: Pt (100) surfaces are generally considered to be less active in oxygen reduction reactions (ORR). The synthesis process is from the high exponential {311} plane of multi-branched structure to {100} plane with Ni2+ as the medium. Despite its surface being covered by {100} surface, the platinum polypod cube still exhibits high ORR activity, and its half potential and current density are close to those of the most active platinum-nickel alloy catalysts, and the catalytic performance of the catalyst is similar to that of the most active platinum-nickel alloy catalysts. The results show that the excellent ORR performance of Pt polypod cubic bifurcation structure is the combination of high catalytic activity of high exponential crystal plane and low exponential flat crystal plane with low contact resistance of electrode. A new method of surface control and ORR catalyst design.
4. Controllable synthesis of copper-platinum alloys with high exponential crystal planes: Pt is widely used in proton exchange membrane fuel cells because of its high catalytic performance, but its high price restricts the further commercialization of fuel cells, so it is important to improve the catalytic activity of Pt to reduce costs. In order to improve the catalytic performance of Pt, Pt forms Pt-based alloys with other metals M (M = Pd, Co, Ni, Fe, Au, Cu) and so on; (2) Pt nanocrystals with high exponential planes were synthesized by adding surface protectors in the synthesis system. However, there are serious shortcomings in both methods, which makes the study of alloy catalysis not mature enough. A new method for synthesizing copper-platinum alloys was developed on the basis of previous studies, which opened up a new field of vision for the preparation of alloys with high catalytic activity.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O643.36;TM911.4
本文编号：2247548
[Abstract]:The increasing use of fossil energy not only improves the quality of our lives, but also brings serious environmental pollution. Therefore, developing a green energy is the only way to alleviate the current environmental crisis. However, the high efficiency of proton exchange fuel cell depends on expensive platinum and platinum-based precious metal catalysts, which seriously hinder the large-scale application of proton exchange fuel cell. Therefore, the main content of proton exchange fuel cell research is to improve the catalytic activity of platinum. In this paper, a series of fuel cell catalysts with high catalytic activity were developed by adjusting the synthesis parameters in the simple system of water-ethylene glycol.
1. Controlled synthesis and electrocatalytic properties of platinum multipedal branched nanostructures: Surface parameters (especially specific surface area, surface atom distribution) of nanocrystals are important factors affecting the performance of nanocatalysts. The structural characteristics of branched nanostructures make them have good catalytic performance, but it is difficult to separate them in practical synthesis. In this work, the controllable synthesis of PT nanostructures with different number of branches was achieved by controlling the amount of HCl added in the synthesis process. In this reaction, oxidation and etching of HCl play three roles in the synthesis of nanocrystals: (1) regulating the crystallinity of nanocrystals and seeds; (2) regulating {111}, {111}, { The number of 100} crystal planes; (3) the concentration of newly supplied atoms is regulated. Therefore, the tripod, quadruped, hexapod and Octopod PT nano-branching structures can be synthesized by controlling the amount of HCl etchant added. This controlled synthesis method reveals the mechanism of the effect of the structure on the electrocatalytic performance, and tests show that platinum Octopod nano-branching structures can be synthesized. This method opens up a new field of vision for the synthesis and properties of complex nanostructures.
2. Controlled synthesis and Electrocatalytic Performance of concave cubic platinum-graphene oxide composites: Nowadays, nano-Pt catalysts are used as redox reactions (ORR) in fuel cells, but achieving stability and high activity at the same time is still a challenging task. In this work, we synthesized a highly concave and high-finger composite. Nano-cubic block (HCC) with several crystal planes. The stability of Pt HCC can be significantly improved by self-assembly with graphene to form a composite catalyst, which exhibits very high catalytic performance. The catalytic performance of the composite catalyst is seven times higher than that of commercial Pt/C catalyst. V, 63 mV higher than Pt/C, and even better than the highest-recorded porous nano-Pt-Ni in the literature. This work opens up a new way to control the catalytic performance of noble metal nanocatalysts based on inert carriers.
3. Nickel ion-assisted synthesis and electrocatalytic properties of platinum polypod cubic branched structures: Pt (100) surfaces are generally considered to be less active in oxygen reduction reactions (ORR). The synthesis process is from the high exponential {311} plane of multi-branched structure to {100} plane with Ni2+ as the medium. Despite its surface being covered by {100} surface, the platinum polypod cube still exhibits high ORR activity, and its half potential and current density are close to those of the most active platinum-nickel alloy catalysts, and the catalytic performance of the catalyst is similar to that of the most active platinum-nickel alloy catalysts. The results show that the excellent ORR performance of Pt polypod cubic bifurcation structure is the combination of high catalytic activity of high exponential crystal plane and low exponential flat crystal plane with low contact resistance of electrode. A new method of surface control and ORR catalyst design.
4. Controllable synthesis of copper-platinum alloys with high exponential crystal planes: Pt is widely used in proton exchange membrane fuel cells because of its high catalytic performance, but its high price restricts the further commercialization of fuel cells, so it is important to improve the catalytic activity of Pt to reduce costs. In order to improve the catalytic performance of Pt, Pt forms Pt-based alloys with other metals M (M = Pd, Co, Ni, Fe, Au, Cu) and so on; (2) Pt nanocrystals with high exponential planes were synthesized by adding surface protectors in the synthesis system. However, there are serious shortcomings in both methods, which makes the study of alloy catalysis not mature enough. A new method for synthesizing copper-platinum alloys was developed on the basis of previous studies, which opened up a new field of vision for the preparation of alloys with high catalytic activity.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O643.36;TM911.4
【参考文献】
相关期刊论文 前1条
1 衣宝廉;燃料电池的原理、技术状态与展望[J];电池工业;2003年01期
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