氮掺杂炭材料的制备及其电催化氧还原性能研究
发布时间：2019-02-15 08:44
【摘要】：燃料电池作为一种新型的洁净绿色能源技术,因其不受卡诺循环的限制而具有能量转换效率高、环境亲和性好、能量密度高、启动速度快、无噪音等优点。然而,由于燃料电池本身阴极动力学性质的迟缓性以及较大的氧阴极过电位,使得氧还原反应(ORR)极度缓慢。目前,铂碳催化剂被认为是现有水平中一种最好的氧还原活性催化剂,可是,由于铂是一种自然界储存量稀少且价格昂贵的贵金属,所以,价格低廉且具有氧还原催化活性与稳定性高的非贵金属催化剂用于来取代铂碳催化剂,是最终实现其大规模商业化应用的可行途径。因此,本文旨在探索新型的合成方法和以廉价、易得的碳源为原料,通过高温裂解法制备了高度石墨化、高氧还原活性的含氮炭材料,将其作为一种应用于燃料电池阴极之上的有效氧还原催化剂。对本课题所制备催化剂的结构和性能进行了一系列的分析和总结,具体如下:(1)通过以廉价的商业阳离子交换树脂D113作为碳源,经过酸预处理后,Fe Cl2·4H2O为交换剂,甘氨酸为氮源,以碳和氮的不同质量比例制备了四种不同的含氮炭材料。通过HRTEM、XRD和XPS表征,发现了Fe Cl2作为一种石墨化催化剂可以大大提高炭材料的石墨化程度,而氮含量的多少与氧还原活性并不成一定的比例关系,同时在此过程中总结出Valley-N是一种有助于提高ORR催化活性的N类型。(2)采用不同的交换剂:Fe Cl2·4H2O和Ni(Ac)2·4H2O为交换剂,甘氨酸为氮源,分别制备了八种不同的含炭材料和含氮炭材料。通过分析,发现金属的存在大大提升了材料氧还原活性,并且不同的金属盐所催化石墨化制备的碳材料的形貌截然不同,且二者的含氮炭材料对氧还原的贡献是不一样的。(3)研究不同氮源的影响:0.45M的Co Cl2·6H2O为交换剂,在甘氨酸和NH3的掺杂下,研究不同的掺杂方式及顺序和不同氮源对氧还原活性的影响。通过分析证实了以Co盐催化石墨化制备的炭材料,经先甘氨酸900℃氮掺杂,再在NH3950℃热处理掺氮制备的催化剂具有高度的催化能力和氧还原活性。
[Abstract]:As a new clean green energy technology, fuel cell has the advantages of high energy conversion efficiency, good environmental affinity, high energy density, fast start-up speed and no noise due to its no restriction of Carnot cycle. However, because of the retardation of cathode dynamics and the overpotential of oxygen cathode, the oxygen reduction reaction of (ORR) is extremely slow. At present, platinum-carbon catalysts are considered to be the best catalysts for oxygen reduction at present. However, platinum is a rare and expensive precious metal in nature. Non-noble metal catalysts with low cost and high catalytic activity and stability of oxygen reduction are used to replace platinum-carbon catalysts, which is a feasible way to realize their commercial applications on a large scale. Therefore, the purpose of this paper is to explore new synthesis methods and to prepare nitrogen-containing carbon materials with high graphitization and high oxygen reduction activity by high-temperature pyrolysis with cheap and readily available carbon sources. It is used as an effective oxygen reduction catalyst for fuel cell cathodes. The structure and properties of the catalysts prepared in this paper were analyzed and summarized as follows: (1) by using the cheap commercial cation exchange resin D113 as the carbon source, after acid pretreatment, Fe Cl2 4H2O was used as the exchanger. Four kinds of nitrogen-containing carbon materials were prepared by using glycine as nitrogen source at different mass ratios of carbon and nitrogen. By HRTEM,XRD and XPS characterization, it was found that Fe Cl2 as a graphitization catalyst could greatly improve the graphitization degree of carbon materials, but the amount of nitrogen content was not proportional to oxygen reduction activity. At the same time, it was concluded that Valley-N is a kind of N type that can improve the catalytic activity of ORR. (2) different exchangers: Fe Cl2 4H2O and Ni (Ac) _ 2 4H2O are used as exchangers, glycine as nitrogen source, and glycine as nitrogen source. Eight kinds of carbon containing materials and nitrogen containing carbon materials were prepared. Through analysis, it was found that the presence of metals greatly enhanced the oxygen reduction activity of the materials, and the morphology of carbon materials prepared by different metal salts was very different. The contribution of nitrogen-containing carbon materials to oxygen reduction is different. (3) the effects of different nitrogen sources on oxygen reduction are studied. (3) the effects of different nitrogen sources: 0.45m Co Cl2 6H2O as exchanger, doped with glycine and NH3, The effects of different doping modes and sequences and different nitrogen sources on oxygen reduction activity were studied. The results show that the carbon materials prepared by Co salt catalyzed graphitization have high catalytic activity and oxygen reduction activity after being doped with glycine at 900 鈩，
本文编号：2423164
[Abstract]:As a new clean green energy technology, fuel cell has the advantages of high energy conversion efficiency, good environmental affinity, high energy density, fast start-up speed and no noise due to its no restriction of Carnot cycle. However, because of the retardation of cathode dynamics and the overpotential of oxygen cathode, the oxygen reduction reaction of (ORR) is extremely slow. At present, platinum-carbon catalysts are considered to be the best catalysts for oxygen reduction at present. However, platinum is a rare and expensive precious metal in nature. Non-noble metal catalysts with low cost and high catalytic activity and stability of oxygen reduction are used to replace platinum-carbon catalysts, which is a feasible way to realize their commercial applications on a large scale. Therefore, the purpose of this paper is to explore new synthesis methods and to prepare nitrogen-containing carbon materials with high graphitization and high oxygen reduction activity by high-temperature pyrolysis with cheap and readily available carbon sources. It is used as an effective oxygen reduction catalyst for fuel cell cathodes. The structure and properties of the catalysts prepared in this paper were analyzed and summarized as follows: (1) by using the cheap commercial cation exchange resin D113 as the carbon source, after acid pretreatment, Fe Cl2 4H2O was used as the exchanger. Four kinds of nitrogen-containing carbon materials were prepared by using glycine as nitrogen source at different mass ratios of carbon and nitrogen. By HRTEM,XRD and XPS characterization, it was found that Fe Cl2 as a graphitization catalyst could greatly improve the graphitization degree of carbon materials, but the amount of nitrogen content was not proportional to oxygen reduction activity. At the same time, it was concluded that Valley-N is a kind of N type that can improve the catalytic activity of ORR. (2) different exchangers: Fe Cl2 4H2O and Ni (Ac) _ 2 4H2O are used as exchangers, glycine as nitrogen source, and glycine as nitrogen source. Eight kinds of carbon containing materials and nitrogen containing carbon materials were prepared. Through analysis, it was found that the presence of metals greatly enhanced the oxygen reduction activity of the materials, and the morphology of carbon materials prepared by different metal salts was very different. The contribution of nitrogen-containing carbon materials to oxygen reduction is different. (3) the effects of different nitrogen sources on oxygen reduction are studied. (3) the effects of different nitrogen sources: 0.45m Co Cl2 6H2O as exchanger, doped with glycine and NH3, The effects of different doping modes and sequences and different nitrogen sources on oxygen reduction activity were studied. The results show that the carbon materials prepared by Co salt catalyzed graphitization have high catalytic activity and oxygen reduction activity after being doped with glycine at 900 鈩，
本文编号：2423164
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