三元铂基纳米催化剂的制备及其对乙醇氧化催化行为的研究

发布时间：2018-06-06 23:31

本文选题：燃料电池 + 直接乙醇燃料电池　；参考：《西南大学》2017年硕士论文

【摘要】：直接乙醇燃料电池(Direct ethanol fuel cell,DEFC)利用液体乙醇为燃料,可以直接将储存在乙醇中的化学能转化为电能,是一种具有广阔应用前景的供能系统,对于解决当今世界面临的能源危机和环境污染这两大难题具有十分重要的意义。目前,DEFC因为乙醇燃料的理论能量密度高,毒性小,成本低廉,可以通过生物质发酵的方法大规模生产等诸多优点而受到了国内外科研工作者的广泛关注。迄今为止,贵金属Pt是最常用的DEFC阳极催化剂,但是,由于Pt储量少、价格昂贵并且容易受到中间产物的毒化,从而严重阻碍了DEFC的商业化进程。因此,制备高效、低成本的Pt基合金阳极催化剂成为DEFC研究领域的重大课题。本论文概述了DEFC的研究背景,介绍了DEFC的工作原理和阳极反应机理,总结了DEFC阳极催化剂的研究进展,分析了催化剂载体材料对催化剂催化性能的影响。在此基础上,以制备高效、低成本的Pt基合金阳极催化剂为目标,探索通过调控催化剂的元素组成以及催化剂的载体材料来提高其对乙醇氧化反应的催化性能,并且进一步分析其内在机理,为DEFC阳极催化剂催化性能的提升提供有益的借鉴。本论文的主要研究内容归纳如下:1.石墨烯负载Pt基合金纳米颗粒作为DEFC阳极催化剂的应用运用改性的多元醇一步还原法,在石墨烯上直接生长Pt1Ru0.5Sn0.5三元合金纳米颗粒(Pt1Ru0.5Sn0.5-RGO),Pt1Ru1二元合金纳米颗粒(Pt1Ru1-RGO)以及Pt1Sn1二元合金纳米颗粒(Pt1Sn1-RGO),并把它们作为直接乙醇燃料电池中乙醇氧化的催化剂材料。为了便于比较,三者均在相同的实验条件下和商业化Pt-C催化剂进行了比较。实验中,Pt1Ru0.5Sn0.5-RGO显示了高达51.7 m2·g-1 Pt的电化学活性面积(ECSA),是商业化Pt-C的1.49倍。在乙醇氧化的催化反应中,Pt1Ru0.5Sn0.5-RGO催化剂的质量电流密度(1287 mA·mg-1 Pt)和面积电流密度(24.89 A·m-2 Pt)分别是商业化Pt-C催化剂的2.07倍和1.38倍。此外,与商业化Pt-C,Pt1Ru1-RGO和Pt1Sn1-RGO催化剂相比,Pt1Ru0.5Sn0.5-RGO催化剂表现出最负的初始反应电位(0.633 V)和最好的催化稳定性。研究结果表明,石墨烯负载Pt1Ru0.5Sn0.5三元合金纳米颗粒的催化剂Pt1Ru0.5Sn0.5-RGO,因为石墨烯的优异特性以及Pt、Ru、Sn三种元素之间的协同作用,表现出对乙醇氧化具有最好的催化活性和最佳的催化稳定性,具有一定的应用潜力。2.不同碳载体负载Pt3Ru0.5Cu0.5三元合金纳米颗粒对乙醇氧化反应的影响运用NaBH4一步还原法,分别制备由石墨烯片层相互交织堆叠形成的多孔三维石墨烯作为载体负载Pt3Ru0.5Cu0.5三元合金纳米颗粒(Pt3Ru0.5Cu0.5-3D RGO),零维Vulcan XC-72碳粉作为载体负载Pt3Ru0.5Cu0.5三元合金纳米颗粒(Pt3Ru0.5Cu0.5-C)以及一维碳纳米管作为载体负载Pt3Ru0.5Cu0.5三元合金纳米颗粒(Pt3Ru0.5Cu0.5-CNT)。将这些不同碳载体负载的三元合金纳米颗粒用作乙醇氧化反应的催化剂,同时与商业化Pt-C催化剂进行了比较。研究结果表明,三维石墨烯作为载体的Pt3Ru0.5Cu0.5-3D RGO催化剂具有最大的电化学活性面积(ECSA)(54.8 m2·g-1 Pt),对乙醇氧化反应具有最高的质量电流密度(1378 mA·mg-1 Pt)和最高的面积电流密度(25.14 A·m-2 Pt),最好的催化活性以及最佳的催化稳定性。可见,由石墨烯片层相互交织堆叠形成的多孔三维石墨烯载体材料促进了Pt3Ru0.5Cu0.5三元合金纳米小颗粒的均匀沉积和分散,并且在催化反应的过程中有效阻止了Pt3Ru0.5Cu0.5三元合金纳米小颗粒的团聚,进而提高了催化剂中Pt的利用率,同时三维石墨烯的多孔结构还促进了乙醇氧化反应过程中的传质速率和电子传输速率。因此,与零维和一维碳载体相比,三维石墨烯作为载体材料在Pt负载量相同的情况下提高了催化剂的催化活性与稳定性,证明了三维石墨烯是一种比较有应用前景的催化剂载体材料。综上所述,本论文的工作主要揭示了通过合金化的方法改变催化剂的元素组成,以及选用合适的催化剂载体材料,结合催化剂组成元素之间的协同作用和载体材料的优异特性,可以明显提高直接乙醇燃料电池阳极催化剂的催化活性和催化稳定性。
[Abstract]:Direct ethanol fuel cell (Direct ethanol fuel cell, DEFC) uses liquid ethanol as fuel and can directly convert chemical energy stored in ethanol into electrical energy. It is a promising energy supply system. It is of great significance to solve the two problems of energy crisis and environmental pollution in the world today. Before, DEFC has been widely concerned by researchers at home and abroad because of its high theoretical energy density, low toxicity and low cost. It has been widely concerned by researchers at home and abroad. So far, precious metal Pt is the most commonly used DEFC anodizing agent. However, because of the low Pt reserves, the price is expensive and is easy to accommodate. It is easy to be poisoned by intermediate products, which seriously hinders the commercialization of DEFC. Therefore, the preparation of high efficiency and low cost Pt based alloy anode catalysts is a major issue in the field of DEFC. This paper summarizes the research background of DEFC, introduces the working principle of DEFC and the mechanism of anode reaction, and summarizes the research progress of the DEFC anode catalyst. The effect of the catalyst carrier material on the catalytic performance of the catalyst was analyzed. On this basis, a high efficient and low cost Pt based alloy anode catalyst was designed to improve the catalytic performance of the catalyst by regulating the element composition of the catalyst and the carrier material of the catalyst, and further analyzing the intrinsic properties of the catalyst. The main research contents of this paper are as follows: 1. the Pt based alloy nanoparticles loaded with graphene are used as the DEFC anode catalyst for the application of the modified polyol one step reduction method to direct the growth of Pt1Ru0.5Sn0.5 three element alloy nanoparticles on the graphene (Pt1Ru). (Pt1Ru 0.5Sn0.5-RGO), Pt1Ru1 two element alloy nanoparticles (Pt1Ru1-RGO) and Pt1Sn1 two element alloy nanoparticles (Pt1Sn1-RGO), and use them as a catalyst for the oxidation of ethanol in direct ethanol fuel cells. For the convenience of comparison, the three were compared with commercial Pt-C catalysts under the same experimental conditions. In the experiment, Pt1Ru0.5Sn0. 5-RGO shows an electrochemical active area of up to 51.7 m2. G-1 Pt (ECSA), which is 1.49 times as high as commercialized Pt-C. In the catalytic reaction of ethanol oxidation, the mass current density (1287 mA. Mg-1 Pt) and area current density (24.89 A. M-2) are 2.07 times and 1.38 times as much as commercialized catalyst. Compared with the Pt-C, Pt1Ru1-RGO and Pt1Sn1-RGO catalysts, the Pt1Ru0.5Sn0.5-RGO catalyst showed the most negative initial reaction potential (0.633 V) and the best catalytic stability. The results showed that the catalyst Pt1Ru0.5Sn0.5-RGO for the Pt1Ru0.5Sn0.5 three element alloy nanoparticles supported by graphene, because of the excellent properties of graphene and the three kinds of Pt, Ru, Sn. The synergistic effect between elements shows the best catalytic activity and the best catalytic stability for ethanol oxidation, and has certain potential application potential.2. with different carbon carrier load Pt3Ru0.5Cu0.5 three element alloy nanoparticles on the oxidation of ethanol by using NaBH4 one-step reduction method to prepare each interlaced stack of graphene lamellae respectively. The porous three-dimensional graphene as carrier load Pt3Ru0.5Cu0.5 three element alloy nanoparticles (Pt3Ru0.5Cu0.5-3D RGO), zero dimension Vulcan XC-72 carbon powder as carrier load Pt3Ru0.5Cu0.5 three element alloy nanoparticles (Pt3Ru0.5Cu0.5-C) and one dimension carbon nanotube as carrier load Pt3Ru0.5Cu0.5 three element alloy nanoparticles (Pt3Ru0.5Cu0.) 5-CNT). The three element alloy nanoparticles loaded with different carbon carriers were used as a catalyst for ethanol oxidation and compared with commercialized Pt-C catalysts. The results showed that the Pt3Ru0.5Cu0.5-3D RGO catalyst with three-dimensional graphene as a carrier had the maximum electrochemical active area (ECSA) (54.8 m2. G-1 Pt), and ethanol oxygen. The reaction has the highest mass current density (1378 mA. Mg-1 Pt) and the highest area current density (25.14 A. M-2 Pt), the best catalytic activity and the best catalytic stability. It can be seen that the porous three-dimensional graphene carrier material, formed by the interlacing and stacking of graphene lamellae, promotes the Pt3Ru0.5Cu0.5 three element alloy nanoparticles Homogeneous deposition and dispersion, and in the process of catalytic reaction effectively prevent the agglomeration of Pt3Ru0.5Cu0.5 three element alloy nanoparticles, and then improve the utilization of Pt in the catalyst. Meanwhile, the porous structure of the three-dimensional graphene also promotes the mass transfer rate and electron transport rate in the process of ethanol oxidation. Therefore, it is with zero dimension and one dimension. Compared with the carbon carrier, the three-dimensional graphene as a carrier material has improved the catalytic activity and stability of the catalyst under the same load of Pt. It is proved that the three-dimensional graphene is a promising catalyst carrier material. In summary, the work of this paper mainly reveals the change of the catalyst element through the method of alloying. It can obviously improve the catalytic activity and catalytic stability of the anode catalyst for direct ethanol fuel cell with the composition of the element, the selection of the suitable catalyst carrier material, the synergistic effect of the elements of the catalyst and the excellent properties of the carrier materials.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4

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