基于生物分子构建非贵金属燃料电池氧还原催化剂的研究

发布时间：2018-04-27 14:27

本文选题：燃料电池 + 非贵金属氧还原催化剂　；参考：《深圳大学》2017年硕士论文

【摘要】：燃料电池是将化学能转化为电能的装置,跟锂离子电池不一样,只要不断地提供燃料和氧化剂,燃料电池就能持续地工作。质子交换膜燃料电池(proton exchange membrane fuel cell,PEMFC)因其工作温度低、能量密度高和无环境污染等特点成为目前研究的热点。但由于PEMFC工作时需要使用大量的贵金属铂作为阴极氧气还原反应(oxygen reduction reaction,ORR)的催化剂导致制备成本过高,限制了其商业化发展。因此,研发具有高活性的、低成本和稳定性好的ORR催化剂对PEMFC的进一步发展至关重要。杂原子(N、P、B和S等)掺杂碳材料能够制备出高活性、高稳定性的ORR催化剂,其中N原子掺杂碳材料的研究得尤为活跃。近些年来,有关N/S双掺杂的催化剂的报道不断出现,研究表明S原子的引入能够进一步提高催化剂的活性。人们认为S原子的引入对催化剂活性位点的形成或者是增加有积极的促进作用,从而进一步提高催化剂的活性。在上述结果基础上,我们探索了基于生物分子构建N/S双掺杂的非贵金属ORR催化剂的方法,并对催化剂的电化学活性进行研究,主要内容包括如下几个方面:1、综述燃料电池ORR非贵金属催化剂的研究进展,重点阐述构建非贵金属催化剂的几个重要成分,包括碳载体、含氮前躯体和过渡金属前驱体。最后确定我们的实验方案。2、简要介绍所需药品和试剂、以及大型仪器设备,并对实验过程中用到的电化学测试手段以及评价ORR催化剂电催化活性的方法进行简要的说明。3、使用生物小分子L-半胱氨酸(L-Cysteine,L-Cys)为氮源前躯体,与商业导电炭黑、氯化铁复合,通过高温炭化,一步合成N/S共掺杂的新型ORR催化剂C/L-Cys/Fe。利用扫描电镜(SEM)和透射电镜(TEM)表征了催化剂的结构和形貌,结果表明催化剂呈现粒子形状,碳层具有有序化石墨结构;结合X射线光电子能谱(XPS)数据分析发现我们制备的C/L-Cys/Fe催化剂存在着不同形态的N和S,证明利用L-半胱氨酸为前驱体,成功合成了N/S共掺杂的ORR催化剂。通过电化学方法测试其催化性能发现,在碱性介质中,催化剂C/L-Cys/Fe表现出优秀的催化活性和良好的稳定性,并在高载量的情况下能达到与商业Pt/C催化剂相当的活性。通过K-L方程拟合表明C/L-Cys/Fe催化氧还原反应是一个四电子过程,能够将O2直接还原为H2O或者OH-,进一步说明催化剂具有较高的活性。4、使用牛血清蛋白(BSA)为前躯体、羧基化碳纳米管(CNT)为碳载体、结合氯化铁,经过热处理制备出N/S共掺杂的ORR催化剂CNT/BSA/Fe。制备的催化剂在碱性条件下具有出众的催化性能,增大负载量其活性可接近商业Pt/C催化剂。同时该催化剂也表现出良好的稳定性。通过计算K-L方程发现氧还原反应在催化剂CNT/BSA/Fe作用下整体上是一个四电子的过程。XPS数据显示吡啶氮、石墨氮以及吡咯氮均存在催化剂中,还有微量的硫也以不同形态掺杂到其中,解释了催化剂具有较好性能的原因。
[Abstract]:A fuel cell is a device that converts chemical energy into electrical energy. Unlike lithium ion batteries, fuel cells can work continuously as long as they continue to provide fuel and oxidizing agents. Proton exchange membrane fuel cells (proton exchange membrane fuel cell, PEMFC) are present at the present time because of their low working temperature, high energy density and no environmental pollution. However, due to the need to use a large number of precious metal platinum as the cathode oxygen reduction reaction (oxygen reduction reaction, ORR) as a result of PEMFC work, the preparation cost is too high and the commercial development is limited. Therefore, the development of the ORR catalyst with high activity, low cost and good stability to the PEMFC is further developed. The doping of carbon materials (N, P, B and S) can produce highly active and highly stable ORR catalysts, in which the study of N atom doped carbon materials is particularly active. In recent years, the reports of N/S dual doped catalysts have emerged. The research shows that the introduction of S atoms can further improve the activity of the catalysts. People think that the activity of the catalyst can be further improved. The introduction of S atoms has a positive effect on the formation or increase of the active site of the catalyst, thus further improving the activity of the catalyst. On the basis of the above results, we explored the method of constructing a N/S double doped ORR catalyst based on biological molecules, and studied the electrochemical activity of the catalyst. The following aspects include: 1, review the progress in the research of non precious metal catalysts for fuel cell ORR, focusing on the construction of several important components of non precious metal catalysts, including carbon carriers, nitrogen containing precursors and transition metal precursors. Finally, our experimental scheme.2 is determined, and the required drugs and reagents, as well as large instruments and equipment, are briefly introduced. The electrochemical testing methods used in the experiment and the method of evaluating the electrocatalytic activity of ORR catalyst are briefly described,.3, using small molecule L- cysteine (L-Cysteine, L-Cys) as the precursor of nitrogen source, combined with commercial conductive carbon black, ferric chloride, through high temperature carbonization, and one step synthesis of a new N/S Co doped ORR catalyst C. /L-Cys/Fe. characterized the structure and morphology of the catalyst by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the catalyst presented particle shape and the carbon layer had an ordered graphite structure. Combined with X ray photoelectron spectroscopy (XPS) data, it was found that the C/L-Cys /Fe catalyst prepared by us had different forms of N and S, which proved to use L- cysteine. As precursor, N/S Co doped ORR catalyst was successfully synthesized. The catalytic performance of the catalyst was tested by electrochemical methods. In alkaline medium, the catalyst C/L-Cys/Fe showed excellent catalytic activity and good stability, and could reach the same activity as commercial Pt/C catalyst in the case of high load. The K-L equation fit table. The catalytic oxygen reduction reaction of the Ming C/L-Cys/Fe is a four electron process, which can directly reduce O2 to H2O or OH-. It further illustrates that the catalyst has a high active.4, using bovine serum protein (BSA) as the precursor, carboxyl carbon nanotubes (CNT) as a carbon carrier and iron chloride, through heat treatment, to prepare a N/S Co doped ORR catalyst CNT/BSA/. The catalyst prepared by Fe. has excellent catalytic performance under the alkaline condition, which increases the load and its activity is close to the commercial Pt/C catalyst. Meanwhile, the catalyst also shows good stability. By calculating the K-L equation, the oxygen reduction reaction was found to be a four electron process.XPS data on the whole of the catalyst CNT/BSA/Fe. There is a catalyst in both pyridine nitrogen, graphite nitrogen and pyrrole nitrogen, and a trace amount of sulfur is also doped in different forms, which explains the reasons for the better performance of the catalyst.

【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4

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