成果報告書詳細
管理番号20090000000024
タイトル*平成20年度中間年報 固体高分子形燃料電池実用化戦略的技術開発 要素技術開発 カーボンアロイ触媒
公開日2010/2/19
報告書年度2008 - 2008
委託先名国立大学法人東京工業大学 国立大学法人東京大学 国立大学法人北陸先端科学技術大学院大学 国立大学法人群馬大学 日清紡績株式会社 帝人株式会社
プロジェクト番号P05011
部署名燃料電池・水素技術開発部 燃料電池グループ
和文要約以下本編抜粋:1. 研究開発の内容及び成果等 1.カーボンアロイ触媒作製法の確立 1. 原料分子構造、炭素化条件と生成炭素材料構造の相関 1)原料分子構造の設計 (a) 1次構造に着目した芳香族高分子の設計 1次元構造を考慮し、酸素、窒素を含有芳香族高分子として、ポリアミド、ポリイミド、ポリアゾールを合成し、これを原料としてカーボンアロイ触媒を調製した。
英文要約The polymer electrolyte fuel cell (PEFC) is expected to be a promising power source of high efficiency, low operating temperature, and low pollution for transportation and residential applications. Considerable effort has been devoted to the solving of several problems associated with the use of fuel cell cathode electrocatalysts. Conventionally, Platinum (Pt) has been used as a cathode electrocatalyst for the slow oxygen reduction reaction (ORR). However, Pt is too expensive to use as a cathode catalyst. For the practical use of PEFCs, alternative low-cost non-Pt cathode catalysts with high power loads are necessary. Carbon based materials doped with nitrogen are receiving much attention, owing to their relatively high ORR activities. These materials, a mixture of carbon materials modified with inexpensive elements such as boron and nitrogen, are known as “carbon alloys”, and we call these materials “carbon alloy catalysts” (CACs) due to their ORR activity.
Nitrogen-doped carbon-based catalysts are attracting increased interest as potential Pt-free electrode catalysts for PEFCs. Thus, we have been studying the design rules to prepare carbon materials which contain nitrogen atoms derived from materials such as polyamides (PA), polyimides (PI) and polyazoles (Az).
Eonset ( defined as the voltage at which a the reduction current density of -10 x 10-6 A cm-2 is observed ) of nitrogen-free CACs, prepared via pyrolysis of nitrogen-free polymers such as phenol resin, is 0.49V. The average Eonset of CACs prepared by pyrolyzed PIs, Pas and Azs are is 0.53V, 0.60 V and 0.65 V, respectively. The maximum Eonset recorded is 0.73 V for a phenol OH containing Az. The CACs prepared by pyrolyzed mixtures of PIs, PAs or Azs with iron phthalocyanine (FePc) show a higher Eonset of 0.82 V. These values are higher than for those samples containing no metal complex, and also higher than pyrolyzed phenol resins with FePc or CoPc.
Next the morphology and chemical structure of CACs prepared from pyrolized PAs with FePc was studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photo electron spectroscopy (XPS). The shapes of the (002) diffractions of pyrolized PAs containing no FePc (PAno) and those with FePc ( 1wt % Fe) (PAFe1) are very broad, but those of pyrolized PAs with FePc ( 3wt % Fe) (PAFe3) is very sharp. The TEM images of PAno and PAFe1 show the structures that are characteristic of amorphous carbons. The TEM images of PAFe3 show graphite-like carbons. From these results, it is suggested that the addition of FePc accelerates the graphitlization of carbons. However, both PAFe1 and PAFe3 show relatively higher Eonset of 0.78 and 0.82 V, respectively, therefore a graphitic structure is not necessary for ORR activity. The chemical species of residual nitrogens and oxygens of CACs were characterized by XPS spectra.
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