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基于纳米碳材料的直接甲醇燃料电池阳极催化剂的控制合成及性能研究

发布时间:2019-03-15 11:07  文章来源:笔耕文化传播
【摘要】:由于能源危机与环境污染的持续加剧,直接甲醇燃料电池作为一种潜在的能源装置因为具有较高的能量转换效率和较低的污染排放而吸引了学术界及工程界的广泛关注。然而,低成本、高性能阳极催化剂的匮乏使得直接甲醇燃料电池的大规模商业化受到了很大的限制。近年来,纳米碳材料(如碳纳米管和石墨烯等)因其优异的物理化学性质和独特的纳米尺寸效应而被认为是一种十分有前景的支撑材料,可以用来构建先进的复合催化剂。本论文采用一系列新颖的制备路线合成了多种基于纳米碳材料的直接甲醇燃料电池阳极催化剂,同时深入考察了复合催化剂的微结构、形貌及组成对于甲醇氧化反应催化性能的影响。具体研究内容如下: 1.低缺陷碳纳米管负载铂及铂钴合金催化剂的控制合成及性能研究。 为了在碳纳米管的外壁引入含氧官能团,我们利用硝酸铂水解所产生的硝酸对碳纳米管进行轻微地氧化。由于水解产生的硝酸其浓度远远小于传统酸处理过程中的酸浓度,因此在碳纳米管表面仅会形成少量的结构缺陷,从而显著提高其导电性。与酸处理碳纳米管负载铂催化剂相比,低缺陷碳纳米管负载铂催化剂表现出较好的电催化活性和优异的抗中毒能力。在此基础上,铂钴合金催化剂也可以经由相似的方法负载在低缺陷碳纳米管表面。在复合体系中,钴组分的存在不仅能使催化剂中铂组分的还原态程度升高,还可以为反应中间产物CO的氧化提供充足的氧源。因而铂钴合金-低缺陷碳纳米管催化剂相比于铂-低缺陷碳纳米管和商用的铂钌-炭黑(Vulcan XC-72)催化剂具有明显增强的催化活性。 2.低缺陷石墨烯负载铂及钯催化剂的控制合成及性能研究。 从本质上来说,石墨烯可以被认为是碳纳米管展开之后的产物,这就意味着其物理化学性质与碳纳米管相似,但具有更大的比表面积。基于此,低缺陷碳纳米管负载催化剂的设计思路可以进一步拓展来合成低缺陷石墨烯-铂催化剂。由于合成条件更为温和,负载于低缺陷石墨烯表面的铂粒子相比于化学还原石墨烯表面的铂粒子分散性更高。更为重要的是,几乎完好的石墨烯结构可以显著降低复合材料的电荷转移电阻并提高铂颗粒的催化活性。此外,考虑到金属钯相对便宜的价格,我们采用钯替换铂来降低低缺陷石墨烯负载阳极催化剂的制备成本。最终得到的钯-低缺陷石墨烯催化剂对酸性介质下的甲酸氧化和碱性介质下的甲醇氧化均表现出了不同寻常的催化活性。相较而言,后者具有更好的电催化稳定性。 3.二氧化锰改性的石墨烯负载铂及钯催化剂的控制合成及性能研究。 石墨烯骨架中的碳原子可以与Mn04一离子发生直接的氧化还原反应,生成二氧化锰-石墨烯复合物。研究表明,以二氧化锰-石墨烯作为载体材料可以促进金属铂和金属钯颗粒的沉积,防止发生团聚现象。在电催化反应过程中,二氧化锰的引入一方面能加速电解质的扩散,同时还能保证毒性物种和质子在电极表面的快速输运。因此,二氧化锰改性的石墨烯负载催化剂的催化性能明显高于未改性的石墨烯及炭黑负载催化剂。 4.三维多孔的石墨烯-氮化碳杂化气凝胶负载铂催化剂的控制合成及性能研究。 氮掺杂被证明是一种提升石墨烯基催化剂电化学性能的有效手段。在该部分中,我们成功地构建了由石墨烯和氮化碳纳米层组成的三维多孔复合结构。通过调节石墨烯与氮化碳的投料比,可以得到具有不同氮含量的石墨烯-氮化碳杂化气凝胶。当负载了金属铂纳米颗粒之后,所获得的复合材料被作为阳极催化剂催化甲醇氧化反应。电化学测试结果表明,三维多孔的石墨烯-氮化碳杂化气凝胶负载铂催化剂显示出较高的电催化活性,突出的抗中毒能力以及可信赖的稳定性,远远优于对比样品。
[Abstract]:Because of the continuous increase of energy crisis and environmental pollution, direct methanol fuel cell, as a potential energy device, has attracted the extensive attention of the academic community and the engineering community as a potential energy device because of higher energy conversion efficiency and lower pollution discharge. However, the lack of low cost, high performance anode catalysts has greatly limited the large-scale commercialization of direct methanol fuel cells. In recent years, nano-carbon materials (such as carbon nanotubes and graphene, etc.) are considered to be a very promising support material due to its excellent physical and chemical properties and unique nano-size effects, and can be used to build advanced composite catalysts. In this paper, a series of novel direct methanol fuel cell anode catalysts based on nano-carbon materials are synthesized by a series of novel preparation routes, and the effect of the microstructure, morphology and composition of the composite catalyst on the catalytic performance of the methanol oxidation reaction is also investigated. The specific contents of the study are as follows: 1. Synthesis and performance of low-defect carbon nanotube supported platinum and platinum-cobalt alloy catalyst to introduce an oxygen-containing functional group on the outer wall of the carbon nanotube, the nitric acid produced by the hydrolysis of the platinum nitrate is used to make a slight reduction of the carbon nanotubes, The nitric acid produced by the hydrolysis is much smaller than the acid concentration in the conventional acid treatment process, so that only a small amount of structural defects are formed on the surface of the carbon nanotube, thereby remarkably improving the concentration of the nitric acid, Compared with the acid-treated carbon nanotube-supported platinum catalyst, the low-defect carbon nano-tube supported platinum catalyst exhibits good electrocatalytic activity and excellent resistance to corrosion On this basis, the platinum-cobalt alloy catalyst can also be supported in a low-defect carbon nanometer by a similar method. In that composite system, the existence of the cobalt component can not only increase the reduction state of the platinum component in the catalyst, but also provide sufficient oxidation of the CO in the reaction intermediate product. The platinum-cobalt alloy-low-defect carbon nanotube catalyst has a significantly enhanced acceleration compared to a platinum-low-defect carbon nanotube and a commercial platinum-carbon-black (Vulcan XC-72) catalyst as compared to a platinum-low-defect carbon nanotube catalyst. Chemical activity.2. Control and synthesis of low-defect grapheme supported platinum and catalyst and performance studies. in essence, the graphene can be considered a product of the carbon nanotube deployment, which means that its physicochemical properties are similar to that of the carbon nanotubes, but with The design idea of the low-defect carbon nanotube loading catalyst can be further expanded to synthesize the low-defect stone. ink-platinum catalyst, platinum particles supported on the surface of a low-defect graphene due to the more moderate synthesis conditions, platinum on the surface of the chemically-reduced graphene, More important, the almost intact graphene structure can significantly reduce the charge transfer resistance of the composite and increase the platinum The catalytic activity of the particles is also taken into account. In addition, considering the relatively inexpensive price of the metal, we use the replacement of platinum to lower the low-defect graphene load anode The preparation cost of the nodulizer is as follows: the finally obtained graphite-low-defect graphene catalyst has different effects on the oxidation of the methanol under the acid medium and the oxidation of the methanol under the alkaline medium The latter has a better catalytic activity than in the case of the latter. 3. Electrocatalytic stability of manganese dioxide-modified graphene-supported platinum and catalyst the carbon atoms in the graphene framework can be directly oxidized and reduced with the Mn4-ion to generate Manganese dioxide-graphene composites. The results show that the use of manganese dioxide-graphene as the carrier material can promote the metal-platinum and metal-graphite particles. during the electrocatalytic reaction, the introduction of the manganese dioxide can accelerate the diffusion of the electrolyte, and the catalytic performance of the manganese dioxide modified graphene loading catalyst is obviously higher than that of the non-modified graphene, Graphene and carbon black supported catalyst.4. Three-dimensional porous graphene-carbon nitride mixed gas gel supported platinum The control and synthesis of the catalyst and the performance study. The nitrogen doping is proved to be a kind of lifting graphite. The effective means of the electrochemical performance of the alkenyl catalysts. In this part, we successfully constructed a graphene and a nitride, by adjusting the feeding ratio of the graphene and the carbon nitride, the three-dimensional porous composite structure can obtain the three-dimensional porous composite structure with different nitrogen, the content of the graphene-carbon nitride hybrid aerogel is The electrochemical test results show that the three-dimensional porous graphene-carbon-nitride mixed gas-gel supported platinum catalyst shows high electrocatalytic activity, outstanding anti-poisoning ability and can
【学位授予单位】:南京理工大学
【学位级别】:B
【学位授予年份】:2014
【分类号】:TM911.4;O643.36

【引证文献】

相关硕士学位论文 前5条

1 王冬;碳纳米管@介孔碳三维复合材料的电化学性能研究及其对双酚A的灵敏检测[D];武汉工程大学;2017年

2 王燕;一维Pt-M(M=Fe、Co、Ni)纳米催化剂:合成及电催化性能的研究[D];燕山大学;2017年

3 田茶;三维钛基纳米线复合结构的可控合成与甲醇氧化性能研究[D];合肥工业大学;2017年

4 曹肱舶;石墨烯基纳米复合结构的可控生长及电化学性能研究[D];合肥工业大学;2016年

5 佟月宇;碱性直接甲醇燃料电池阳极镍磷复合催化剂的研究[D];浙江大学;2016年



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