【作者】 苏晓晴；

【导师】 张歆；

【作者基本信息】 汕头大学 ， 应用化学， 2010， 硕士

【摘要】 现在新型制备方法的研究对于燃料电池催化剂的性能的提升变得十分重要。本文利用微波多元醇的方法合成了高分散的Pt/C催化剂并研究了不同制备条件对催化剂性能的影响。接着以碳纳米管作为催化剂载体,用微波加热法合成了Pt和Pt-Ru二元金属催化剂。初步探讨了将微波和微乳相结合的方法用于制备Pt-Ru二元合金催化剂。得到了如下结论:1.本论文通过加入醋酸钠,调节溶液pH值,改变催化剂的铂碳质量比,对碳载体进行预处理制备了Pt/C催化剂。利用XRD,TEM,SEM-EDS,CV等手段对制备的纳米粒子的粒径,表面形貌,元素比例以及电催化性能进行了分析表征。实验结果证明添加0.6ml醋酸钠,调节pH值至10,硝酸处理碳载体,铂质量含量为40%的条件下所制备的催化剂具有最均匀的Pt纳米粒子粒径分布和最佳催化性能。2.本论文以改性后的碳纳米管(CNTs)作为载体制备了催化剂。通过XRD,FTIR以及CV等手段进行了表征。结果证明,以碳纳米管作为载体要优于碳粉。碳纳米管经过酸处理改性后,红外测试证明其表面接枝了许多羟基和羧基官能团。酰胺化处理使其表面接枝上了酰胺基团。负载Pt催化剂后其甲醇峰电流密度分别达到580Ag-1Pt和600Ag-1Pt。XRD测试证明Pt-Ru合金纳米粒子的平均粒径为5.2nm。SEM-EDS测试表明Pt与Ru的元素物质的量之比与理论值相符合。催化剂的甲醇氧化电流峰值达到6.15mA,其氧化峰的起始电位比一元Pt催化剂的更低。3.将微波法和微乳法相结合制备Pt-Ru二元催化剂。催化剂经170℃,250℃,600℃处理后粒径在5.2nm,5.5nm和7.1nm左右。TEM测试表明,制备的催化剂纳米粒子具有良好的分散性。经250℃热处理后,纳米粒子的粒径大概在5nm左右。通过SEM-EDS测试了Pt:Ru的物质的量之比,结果与理论值相符。通过控制加料顺序使纳米粒子中的成分得到很好的控制。循环伏安测试表明,不同的温度下,250℃热处理的催化剂催化性能最好,而在triton-100/异丙醇/环己烷/乙二醇的微乳体系中制备的Pt-Ru催化剂具有最佳的电催化性能。更多还原

【Abstract】 Right now, the research of new preparation method is very important for improvement ofthe fuel cell catalysts’performance. In this paper, microwave polyol process has been used toprepare highly dispersed Pt/C catalysts and the different preparing conditions which influencethe catalysts’performance have been investigated. In the next step, we synthesize Pt and Pt-Rubimetallic catalysts using the CNTs as supporters. Microwave combined with microemulsionmethod has been used to prepare Pt-Ru binary alloy catalysts. We make a preliminary researchto the preparing process. The conclusions are following:1、In this paper, we change the conditions such as adding to sodium acetate solution,adjusting pH of solution, changing the weight ratio of Pt:C and pretreating the carbon supporterin the preparing of Pt/C. The catalysts’size, surface morphology, element ratio andelectrochemical performance have been characterized by XRD, TEM, SEM-EDS and CV. Thecatalysts are well-distributed and have best catalytical performance when add to 0.6ml acetatesolution, adjust pH to10, use HNO3 to pretreate carbon powder or control the weight ratio of Ptto 40%.2、We prepare catalysts using modified CNTs as supporter and characterize the catalysts byXRD,FTIR and CV in this thesis. The conclusion can be drawed as follow:the CNTs is moresuperior than carbon powder. The CNTs has grafted many hydroxyl and carboxyl groups whenacid treated. The amide groups have been grafted to CNTs in amidation process. The methanoloxidation peak current density is 580A g-1Pt and 600A g-1Pt respectively when Pt catalystssupported on the modified CNTs. The average size of Pt-Ru alloy nanoparticles is 5.2nm byXRD measurement and the realistic mole ratio of Pt:Ru is conform to theorical ratio accordingto SEM-EDS measurement. The methanol oxidation peak current is 6.15mA and the onsetpotential is lower than Pt catalyst.3、Pt-Ru binarycatalysts are prepared bymicrowave combined with microemulsion method.The size of catalysts is about 5.2nm, 5.5nm and 7.1nm respectively when heating-treated at 170 ℃,250℃and 600℃.The catalysts is well-dispersed byTEM measurement and the size is about5nm when treated at 250℃.The composition of nanoparticles is well consistent with thetheorical ratio in SEM-EDS measurement by controlling the feeding sequence of raw material.The catalysts which are prepared in heating-treated at 250℃show the best performance incyclic voltammograms measurement. Pt-Ru catalysts prepared in the microaemulsion systermcomposed of triton X-100/ n-butanol/ cyclohexane/ ethylene glycol show the best catalyticalperformance.更多还原