發(fā)布時間：2019-02-15 08:44

【摘要】：燃料電池作為一種新型的潔凈綠色能源技術(shù),因其不受卡諾循環(huán)的限制而具有能量轉(zhuǎn)換效率高、環(huán)境親和性好、能量密度高、啟動速度快、無噪音等優(yōu)點。然而,由于燃料電池本身陰極動力學(xué)性質(zhì)的遲緩性以及較大的氧陰極過電位,使得氧還原反應(yīng)(ORR)極度緩慢。目前,鉑碳催化劑被認(rèn)為是現(xiàn)有水平中一種最好的氧還原活性催化劑,可是,由于鉑是一種自然界儲存量稀少且價格昂貴的貴金屬,所以,價格低廉且具有氧還原催化活性與穩(wěn)定性高的非貴金屬催化劑用于來取代鉑碳催化劑,是最終實現(xiàn)其大規(guī)模商業(yè)化應(yīng)用的可行途徑。因此,本文旨在探索新型的合成方法和以廉價、易得的碳源為原料,通過高溫裂解法制備了高度石墨化、高氧還原活性的含氮炭材料,將其作為一種應(yīng)用于燃料電池陰極之上的有效氧還原催化劑。對本課題所制備催化劑的結(jié)構(gòu)和性能進(jìn)行了一系列的分析和總結(jié),具體如下:(1)通過以廉價的商業(yè)陽離子交換樹脂D113作為碳源,經(jīng)過酸預(yù)處理后,Fe Cl2·4H2O為交換劑,甘氨酸為氮源,以碳和氮的不同質(zhì)量比例制備了四種不同的含氮炭材料。通過HRTEM、XRD和XPS表征,發(fā)現(xiàn)了Fe Cl2作為一種石墨化催化劑可以大大提高炭材料的石墨化程度,而氮含量的多少與氧還原活性并不成一定的比例關(guān)系,同時在此過程中總結(jié)出Valley-N是一種有助于提高ORR催化活性的N類型。(2)采用不同的交換劑:Fe Cl2·4H2O和Ni(Ac)2·4H2O為交換劑,甘氨酸為氮源,分別制備了八種不同的含炭材料和含氮炭材料。通過分析,發(fā)現(xiàn)金屬的存在大大提升了材料氧還原活性,并且不同的金屬鹽所催化石墨化制備的碳材料的形貌截然不同,且二者的含氮炭材料對氧還原的貢獻(xiàn)是不一樣的。(3)研究不同氮源的影響:0.45M的Co Cl2·6H2O為交換劑,在甘氨酸和NH3的摻雜下,研究不同的摻雜方式及順序和不同氮源對氧還原活性的影響。通過分析證實了以Co鹽催化石墨化制備的炭材料,經(jīng)先甘氨酸900℃氮摻雜,再在NH3950℃熱處理摻氮制備的催化劑具有高度的催化能力和氧還原活性。
[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，

本文編號：2423164