直接甲醇燃料电池钯基催化剂的制备及其性能研究

发布时间：2018-06-09 15:43

本文选题：钯 + 醇类燃料电池　；参考：《上海师范大学》2017年硕士论文

【摘要】：直接醇类燃料电池作为一种绿色高效的新型能源有望成为传统化石燃料的理想替代物。贵金属铂(Pt)基催化剂是目前直接醇类燃料电池(DAFCs)领域最有效的催化剂,但其所面临的成本较高、储量有限、易中毒等问题严重制约了DAFCs的商业化进程。发展低成本、高性能的催化剂以减少铂的用量、提高使用效率是解决铂资源短缺、降低燃料电池成本、从而实现DAFCs商业化的关键。因此关于低含量铂或无铂催化剂方面的研究有着重要的实际意义。由于钯(Pd)与Pt为同主族元素,电子差异仅为0.77%,大量的工作已经研究了合成新颖、高效的钯基燃料电池催化剂。其中需解决的问题是进一步探究提高钯基催化剂的活性和利用率的实验方案。本论文从制备技术、载体材料、材料形貌与结构的角度,系统探讨了三种不同钯基复合催化剂的设计与制备方法,针对其对于碱性介质中的甲醇电催化性能进行了详细的考察,并进行了相关机理的解释。具体研究工作包括以下内容:(一)利用多巴胺分子氧化自聚所形成的尺寸均一的聚多巴胺纳米球为模板,制备了有序多孔的钯/聚多巴胺纳米花状材料。聚多巴胺作为一种多功能材料包含羟基等官能基团,它的引入有利于在电催化反应中有效氧化除去一氧化碳等碳中间产物,进而显著改善了催化剂的抗毒化能力。(二)采用溴化十六烷基吡啶作为形貌导向剂,通过优化导向剂用量,反应温度,前躯体配比等条件,利用一步水热法成功合成了金钯异质结构。ICP测试结果显示,最优条件下制备的催化剂中Pd与Au的原子比为1/2,Au的引入大大提高了钯的利用率,同时改善了催化性能,该催化剂相比商用催化剂催化活性提高了约7倍。(三)在植酸钠(IP6)的保护下,首先利用水热法合成氧化铜纳米棒,其外围的植酸钠层可与PdCl42-充分结合,再通过还原反应制备了独特的氧化亚铜修饰的钯纳米网状材料。该纳米网由尺寸10 nm左右的纳米粒子融合而成。植酸钠不仅起到桥联剂作用,同时使该材料分散性良好,具有电化学表面积大,稳定性好等特点。氧化亚铜与钯之间的协同作用有利于催化性能的改善。该材料的催化活性分别是商用钯碳以及钯黑催化剂的2.73、3.03倍,并表现出了显著增加的电化学稳定性以及催化电流密度。
[Abstract]:As a new green and efficient energy, direct alcohol fuel cell is expected to be an ideal substitute for traditional fossil fuels. Precious metal Pt / Pt-based catalyst is the most effective catalyst in the field of direct alcohol fuel cell (DAFCs) at present, but its problems such as high cost, limited reserves and easy poisoning seriously restrict the commercialization process of DAFCs. Developing low cost and high performance catalysts to reduce the amount of platinum and improve the efficiency is the key to solve the shortage of platinum resources reduce the cost of fuel cells and realize the commercialization of DAFCs. Therefore, the research on low-content platinum or non-platinum catalysts has important practical significance. Since palladium (PD) and Pt are the same group elements, the electron difference is only 0.77. A lot of work has been done to study the synthesis of novel and efficient palladium based fuel cell catalysts. The problem to be solved is to further explore the experimental scheme to improve the activity and utilization of palladium-based catalysts. In this paper, three kinds of palladium based composite catalysts were designed and prepared from the angles of preparation technology, carrier materials, morphology and structure of materials, and the electrocatalytic properties of methanol in alkaline media were investigated in detail. The related mechanism is explained. The specific research work includes the following contents: (1) the ordered porous Palladium / Polydopamine nano-flower material was prepared by using the uniform size polydopamine nanospheres formed by the oxidation self-polymerization of dopamine molecule as template. Poly (dopamine), as a multifunctional material, contains functional groups such as hydroxyl groups. The introduction of polydopamine is beneficial to the removal of carbon monoxide and other carbon intermediates in electrocatalytic reactions, thus significantly improving the antipoisoning ability of the catalysts. (2) using hexadecylpyridine bromide as the morphometric guide, the heterogeneity of au and PD was successfully synthesized by one step hydrothermal method. The results of ICP test showed that, by optimizing the dosage of guidance agent, reaction temperature and the ratio of precursor to body, the heterostructure of au and PD was synthesized successfully by one step hydrothermal method. Under the optimum conditions, the PD / au atom ratio of 1 / 2 au in the catalyst greatly improved the utilization of palladium and the catalytic performance. The catalytic activity of the catalyst was about 7 times higher than that of the commercial catalyst. (3) under the protection of sodium phytate (IP _ 6), copper oxide nanorods were synthesized by hydrothermal method. The sodium phytate layer around the nanorods could be fully combined with PdCl _ 42-, and then a unique cuprous oxide modified palladium nano-network material was prepared by reduction reaction. The nanowet is composed of nanoparticles about 10 nm in size. Sodium phytate not only acts as a bridging agent, but also has good dispersion, large electrochemical surface area and good stability. The synergism between cuprous oxide and palladium is beneficial to the improvement of catalytic performance. The catalytic activity of this material is 2.73 times higher than that of commercial palladium carbon and palladium black catalyst respectively, and the electrochemical stability and catalytic current density of the catalyst are obviously increased.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4

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