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1、上海交通大学 硕士学位论文 碳载金属卟啉催化剂的制备及其催化活性的研究 姓名：邓选英 申请学位级别：硕士 专业：化学工程 指导教师：马紫峰 20080101 碳载金属卟啉催化剂的制备及其催化性能的研究 - I - 碳载金属卟啉催化剂的制备及其催化性能的研究碳载金属卟啉催化剂的制备及其催化性能的研究 摘 要 铂及其合金在低温环境下是很好的燃料电池氧还原催化剂， 但其昂 贵的价格和易被CO毒化限制了它作为催化剂的应用以及燃料电池的产 业化发展。金属卟啉化合物在酸性和碱性环境下，对分子氧具有良好的 电催化还原活性，目前被认为是最有希望的催化剂材料，以期待取代贵 金属作为燃料电池氧还原催化剂。 金属卟
2、啉类催化剂包含的三种基本要 素（金属、氮源和碳载体）经过高温热处理后也同样具备金属卟啉配合 物一样的氧还原催化活性，这成为此类催化剂研究的一个新方向。本文 利用微波法和机械混合制备金属卟啉催化剂， 对影响催化剂活性的因素 进行了研究，并重点针对催化剂碳载体和合成工艺，制备了具有高活性 和稳定性的 Co-TMPP 系列氧还原催化剂，采用电化学和物理测试手段 对催化剂氧还原性能及其机理进行了分析。 1. 采用微波合成法制备了 CoTMPP/MWNT 电催化剂, 用透射电子 显微镜(TEM)对电催化剂微观结构进行表征，并通过旋转圆盘（RDE） 和旋转环盘（RRDE）技术对电催化剂的氧还原活性进行了评
3、价。结果 表明，与有机回流合成法制备的催化剂相比，微波法合成的 CoTMPP/MWNT 具有更好的氧还原性能, 半波电位正向移动 110 mV； 与多孔碳负载的 CoTMPP/BP2000 比较，多壁碳纳米管作为载体的 CoTMPP/MWNT 电催化剂的起始电位高 10 mV, 还原电流损失低 21%， 碳载金属卟啉催化剂的制备及其催化性能的研究 - II - 表现出更好的氧还原活性和稳定性。CoTMPP/MWNT 电催化剂表面进 行的氧还原过程中电子转移数为 3.63， H2O2生成百分比为 18.65%。 2. 机械混合三种基本前驱体（硝酸钴、碳黑和 TMPP）合成氧还 原钴系复合电催化剂
4、， 应用电化学手段测试催化剂合成过程中不同混合 过程、溶剂、热处理温度和前驱体的相对比例对电催化剂催化活性的影 响。 Levich-Koutecky 图中可以得知这种复合催化剂在氧还原过程中电子 转移数目在和之间； 超声混合合成的热解混合物显示出比球磨混合 合成的热解混合物更好的氧还原活性； 在酸性介质中发现混合过程的溶 剂对催化剂的性能有很大影响，与 TMPP 的易溶溶剂，二甲基甲 酰胺和醋酸相比较，水中合成的催化剂（TMPP 不溶于水）有更好的催 化活性；同时发现此种催化剂的最佳热处理温度为 600oC, 当 Co: TMPP=1(摩尔比)和/C=5% （质量百分比）时，催化剂显示出最高
5、催化活性。 关键词关键词：金属卟啉； 微波法； 多壁碳纳米管；机械混合； 氧还原反应; 燃 料电池 碳载金属卟啉催化剂的制备及其催化性能的研究 - III - STUDY ON THE PREPARATION AND CATALYTIC ACTIVITY OF CARBON SUPPORED METALLOPORPHYRINS CATALYSTS ABSTRACT Platinum and its alloys are good catalysts for oxygen reduction reaction(ORR) used for fuel cell in low temperature
6、condition, however, these are easily poisoned by CO and the high cost which limit its application as catalyst and the development of industrialization of Fuel Cells. Metalloporphyrins compounds show good electrocatalytic activity for oxygen reduction both in acid and alkaline solutions. It is consid
7、ered as the most promising catalyst material to replace the noble metal for ORR in fuel cells. The three basic precursors of metalloporphyrins, containing non-noble metal, nitrogen sources and carbon support, show the same catalytic activity as metalloporphyrins chelates and this is investigated as
8、a new study direction for these catalysts. This paper applied microwave and mechanically mixing to prepare catalysts and studied the influence factores for catalytic activity. Focusing on carbon support and synthesis technology, we prepared Co-TMPP based catalysts with good catalytic activity and hi
9、gh 碳载金属卟啉催化剂的制备及其催化性能的研究 - IV - stability and investigated the catalytic performance and mechanism of catalysts for ORR by means of electrochemical and physical testing methods. 1. CoTMPP/MWNT electrocatalyst was synthesized by microwave method and its microstructure was characterized using transmis
10、sion electron microscopy. The activities of the CoTMPP/MWNT for ORR were evaluated by rotating disc electrode (RDE) and rotating ring disc electrode (RRDE) technique, respectively. Compared to the traditional organic synthesis, CoTMPP/MWNT electrocatalys which prepared by microwave synthesis has sho
11、wn better performance for oxygen reduction reaction (ORR) and the half wave potential shifted 110 mV positively. CoTMPP/MWNT electrocatalys shows 10 mV higher on-set potential for oxygen reduction and 21% lower reduction current loss in comparison to CoTMPP/BP2000. That means that multiwalled carbon
12、 nanotube supported CoTMPP electrocatalyst has higher catalytic activity and better stability than CoTMPP/BP2000. The number of electrons exchange during ORR and the percentage of peroxide (% H2O2) produced by the reaction were calculated to be 3.63 and 18.65%, respectively. 2. Composite electrocata
13、lysts based on transition metal Co are synthesized for oxygen reduction reaction (ORR) by mechanically mixing three basic precursors containing carbon black, cobalt acetate and Tetramethoxy-phenylporphyrin (TMPP). The influence of various mixing processes, solvents, pyrolysis temperature and precurs
14、or ratios on the ORR activity of electrocatalysts was investigated by means of their electrochemical characteristics. Levich-Koutecky plots showed that the number of transferred electrons during ORR on these catalysts varies 碳载金属卟啉催化剂的制备及其催化性能的研究 - V - between 2 and 4. A pyrolyzed mixture synthesize
15、d by ultrasonication shows better activity for ORR than that by ball milling. The solvent was found to have significant effect on the performance of catalysts in acidic media. The catalyst synthesized in water, a poor solvent of TMPP, had better activity than that synthesized in good solvent of TMPP
16、, such as N, N-Dimethylformamide and acetic acid. The optimal pyrolyzed temperature was observed at 600 C. Various mole ratio and Co/carbon weight ratio were examined. Maximum activity was found at 1:1 TMPP/Co mole ratio and 5% Co/carbon weight ratio. KEYWORDS: metalloporphyrins; microwave synthesis; multi-walled carbon nanotube; mechanically mixing; oxygen reduction reaction; fuel cell 碳载金属卟啉催化剂的制备及其催化性能的研究 - 1 - 第一章 绪 论 1.1 引言 随着现代经济、 科技的快速发展， 能源危机和环境污染成为当今社会发展有待解 决的两个重大课题，可持续性绿
