水热掺氮与菜叶制氧还原反应催化剂的研究

发布时间：2018-04-08 12:36

本文选题：氧还原反应　切入点：催化剂　出处：《重庆大学》2015年硕士论文

【摘要】：燃料电池因具有新颖、清洁、高效、可持续的特点而引起人们的广泛关注,但阴极缓慢的的氧还原反应(ORR)动力学是限制其大规模应用的关键因素。迄今为止,用于氧还原反应(ORR)的最有效和最广泛的催化剂仍然是铂。然而众所周知,Pt系催化剂具有性价高、甲醇耐受性低和稳定性有限等缺点,这些都是新能源系统商业化的阻碍。因此,开发安全高效的非贵金属代替催化剂是十分迫切的任务。研究发现,TM-N/C催化剂,是一种很有希望的Pt/C催化剂的替代物。本论文以广泛应用的Vulcan XC-72为碳源,COCl2·6H2O为过渡金属供体,创新性地提出直接化学还原法和氨水水热掺氮法结合使用,制备出一系列的TM-N/C催化剂。实验讨论了催化剂制备中各种制备条件对催化剂性能的影响,并利用LSV评价了所制备的TM-N/C催化剂的活性与商业Pt/C催化剂活性的差异。结果证明：利用氨水在水热条件下对C材料进行掺氮的方法是有效的,过渡金属的参与、C载体的预先氧化处理对提高催化剂的性能所起的作用是十分重要的,水热掺氮反应的最佳反应条件为180℃,9h,实验所制备的催化剂的峰电位与商业Pt/C催化剂相近。本论文还创新性地选取含丰富叶绿素的绿色植物叶片做为原材料,与C载体Vulcan XC-72和过渡金属Fe、Co盐混合研磨后进行热解处理制备菜叶系列催化剂。考察了热解中各物种的比例、热解的温度和时间、过渡金属的选择和最佳含量等因素对催化剂性能的影响,并详细表征了催化剂的电化学性能。结果表明菜叶做催化剂前驱体的方法是可行的。菜叶的酸浸脱镁步骤、C载体的加入和过渡金属的加入都能使催化剂的催化活性变得更优。实验的最佳条件为酸浸除镁24h,SWA:C=1, Fe wt.%=8%,900℃下热解2h。并验证了菜叶催化剂中对催化剂活性起贡献作用的是叶绿素。在碱性条件下,实验制备的最佳催化剂SWA+C+Fe-900-2h性能与商业Pt/C催化剂的催化性能相近。通过旋转圆盘电极测得SWA+C+Fe-900-2h的转移电子数为3.9接近Pt的4,循环稳定性和耐甲醇性均优于商业Pt/C催化剂。这两种方法制备的TM-N/C催化剂对Pt替代催化剂的发展具有一定的参考价值。
[Abstract]:Fuel cell with new, clean, efficient and sustainable characteristics and aroused extensive attention, but the slow cathodic oxygen reduction reaction (ORR) dynamics is the key factor to limit its large-scale application. So far, for the oxygen reduction reaction (ORR) is the most effective and most widely used catalyst is still however platinum. As everyone knows, Pt catalyst has high stability and low methanol tolerance, limited and other shortcomings, these are hindering the commercialization of new energy systems. Therefore, the development of safe and efficient non noble metal catalyst instead of is a very urgent task. The study found that TM-N/C catalyst is a substitute for the Pt/C catalyst is very promising the. In this paper, the widely used Vulcan XC-72 as carbon source, COCl2 - 6H2O transition metal donor, creatively put forward the direct chemical reduction method and hydrothermal method with ammonia nitrogen doped with a series of preparation The TM-N/C catalyst. The experimental effects of preparation of catalyst preparation conditions on catalyst performance, and use LSV to evaluate the difference of the prepared TM-N/C catalyst activity and commercial activity of the Pt/C catalyst. The results showed that: the use of ammonia under hydrothermal conditions and methods on the C material in nitrogen doping is effective C, transition metal in the pre oxidation treatment of the carrier to improve the catalytic performance of the role is very important, the optimum reaction conditions of hydrothermal reaction of nitrogen doped is 180 DEG C, 9h, C and peak potential of commercial Pt/ catalyst experiment of the prepared catalysts are similar. This paper also creatively chooses green leaves of plants containing abundant chlorophyll as raw materials, and C vector Vulcan XC-72 and transition metal Fe, Co salt mixed grinding after preparation leaves series catalyst was studied. The pyrolysis process of each species in the proportion of thermal pyrolysis, solution The temperature and time, the influence factors of transition metal and the choice of the best content on the catalyst performance, and electrochemical performance of the catalyst were investigated in detail. The results show that the method leaves do catalyst precursor is feasible. The leaves of acid leaching of magnesium removal steps, C carrier addition and adding transition metal can make catalysis the activity of the catalyst becomes better. The optimum experimental conditions for acid leaching of magnesium 24h, SWA:C=1, Fe, wt.%=8%, 900 degrees 2h. and verify the pyrolysis contribution on the catalytic activity of catalyst in the leaves is chlorophyll. In alkaline conditions, the catalytic performance of SWA+C+Fe-900-2h catalyst and the best performance of commercial Pt/C catalyst was prepared. Similar. Number of electron transfer through the rotating disk electrode of SWA+C+Fe-900-2h was measured to be 3.9 to 4 of Pt, cycle stability and methanol resistance are better than that of commercial Pt/C catalyst. The two kinds of methods of preparation The TM-N/C catalyst has a certain reference value for the development of Pt substitute catalyst.

【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TM911.4

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