甲醇电氧化PtRu催化剂载体及助催化剂调控研究

发布时间：2018-05-03 03:40

  本文选题：燃料电池 + 阳极　； 参考：《大连理工大学》2017年博士论文

【摘要】：直接甲醇燃料电池(DMFC)具有理论能量密度高、液体燃料携带方便和系统结构简单等优势,在移动电源和备用电源方面具有广阔的应用前景。但是,甲醇氧化过程(MOR)涉及六电子转移,反应过程复杂、过电位高、动力学速率缓慢,因此研究和开发高活性、高稳定性的MOR电催化剂一直是DMFC研究的热点和难点。PtRu催化剂是目前研究最为广泛的MOR电催化剂,但其催化活性和稳定性仍亟待进一步提高。本论文采用改性传统碳载体、制备新型碳载体和引入第三组元活性金属组分等途径提高了 PtRu基电催化剂的MOR活性和稳定性,系统、深入地研究了催化剂微观形貌、组成和结构与其MOR性能之间的关系。通过间歇微波法合成了 WO_3-C和SnO_2-C两种复合材料,并以该复合材料为载体制备了 PtRu/WO_3-C和PtRu/SnO_2-C催化剂,研究了 WO_3的掺杂量以及热处理对催化剂活性和稳定性的影响。与PtRu/C催化剂相比,PtRu/WO_3-C和PtRu/SnO_2-C催化剂均表现出较高的MOR活性,而且PtRu/WO_3-C的稳定性明显高于PtRu/SnO_2-C催化剂。PtRu/WO_3-C催化剂中WO_3的优化含量为5 wt%。通过固相席夫碱反应体系高温热解和氨气高温处理合成了两种氮掺杂碳材料,并作为载体制备了 PtRu催化剂。研究了含氮前驱体热解温度、载体孔结构、载体氮含量以及氮的类型对PtRu催化剂活性和稳定性的影响。其中,含氮前驱体在700℃热解得到的氮掺杂碳具有较大的比表面积和氮含量(10.6 wt%),以此为载体的PtRu/C催化剂具有最高的MOR活性和稳定性。利用软模板法制备出三种不同孔径的蠕虫孔状介孔碳(WMCs),并作为载体制备了 PtRu催化剂。研究了 WMCs的孔径对催化剂颗粒尺寸及催化性能的影响。研究发现WMCs载体的孔径很大程度上影响了PtRu催化剂的MOR性能。WMCs载体孔径大于PtRu颗粒直径2倍时,PtRu催化剂的电化学面积明显增加,MOR性能高于商品化XC-72R负载的PtRu催化剂。以RuCu/C为硬模板,利用K_2PtCl_4与Cu之间的置换反应并通过调节RuC13溶液的用量,制备出7种不同铂钌比的PtxRuyCu/C三元空心催化剂。研究了不同PtRu原子比对甲醇氧化反应的催化活性和稳定性的影响规律。其中,Pt10Ru1Cu/C表现出最优的MOR催化活性,Pt1Ru1Cu/C表现出最优的抗毒化能力。
[Abstract]:Direct methanol fuel cell (DMFC) has many advantages, such as high theoretical energy density, convenient liquid fuel carrying and simple system structure, so it has a broad application prospect in mobile power supply and backup power supply. However, methanol oxidation process involves six-electron transfer, complex reaction process, high overpotential, slow kinetic rate, so the research and development of high activity, High stability MOR electrocatalyst has been a hot and difficult point in DMFC research. PtRu catalyst is the most widely studied MOR electrocatalyst, but its catalytic activity and stability still need to be improved. In this paper, the MOR activity and stability of PtRu based electrocatalysts were improved by using the modified traditional carbon carrier, the new carbon support and the introduction of the third component active metal component. The microcosmic morphology of the catalyst was studied in detail. The relationship between composition and structure and MOR performance. Two kinds of composite materials WO_3-C and SnO_2-C were synthesized by intermittent microwave method. PtRu/WO_3-C and PtRu/SnO_2-C catalysts were prepared on the basis of the composite materials. The effects of the doping amount of WO_3 and the heat treatment on the activity and stability of the catalysts were studied. Compared with the PtRu/C catalyst, the MOR activity of PtRuS / WO _ 3-C and PtRu/SnO_2-C catalysts were higher, and the stability of PtRu/WO_3-C was obviously higher than that of PtRu/SnO_2-C catalyst .PtRuWO3-C catalyst. The optimized content of WO_3 in the catalyst was 5 wt. Two kinds of nitrogen-doped carbon materials were synthesized by high temperature pyrolysis of solid Schiff base reaction system and high temperature treatment of ammonia, and PtRu catalysts were prepared as support. The effects of pyrolysis temperature, pore structure, nitrogen content and type of nitrogen on the activity and stability of PtRu catalyst were studied. The nitrogen-doped carbon obtained from the pyrolysis of nitrogen-containing precursors at 700 鈩，

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