Chemical state changes of Nafion in model polymer electrolyte fuel cell under oxygen/hydrogen gas atmosphere observed by S-K XANES spectroscopy

Kazuhisa Isegawa, Daehyun Kim, Hiroshi Kondoh

研究成果: Article

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Changes in the chemical states of the sulfonic groups of Nafion in a model polymer electrolyte fuel cell under an oxygen/hydrogen gas atmosphere were studied using sulfur K-edge XANES spectroscopy. First, the chemical state changes in the sulfonic acid groups of both cathode and anode electrodes due to humidity under oxygen/hydrogen gas flow were observed. Reversible spectral changes ascribed to the hydration and dehydration of the sulfonic acid group were observed at both electrodes. This result is similar to the experimental results obtained without introducing oxygen (helium/hydrogen). On the anode, some of the sulfonic acid groups were decomposed to atomic sulfur adsorbed on platinum (Sad) and the amount increased with time. On the cathode, the formation of Sad was suppressed under the oxygen atmosphere. Next, the effects of oxygen gas introduction onto Sad were examined. Sad was at once formed on both electrodes under dry conditions without an oxygen supply. By supplying oxygen gas, Sad on the cathode disappears. Therefore, the catalyst of the cathode has the ability to recover against the poisoning Sad, while that on the anode accumulates.

元の言語English
ページ(範囲)38204-38209
ページ数6
ジャーナルRSC Advances
8
発行部数67
DOI
出版物ステータスPublished - 2018 1 1

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X ray absorption near edge structure spectroscopy
Electrolytes
Fuel cells
Hydrogen
Polymers
Gases
Oxygen
Sulfonic Acids
Cathodes
Anodes
Sulfur
Electrodes
Acids
Oxygen supply
Helium
Platinum
Dehydration
Hydration
Flow of gases
perfluorosulfonic acid

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

これを引用

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title = "Chemical state changes of Nafion in model polymer electrolyte fuel cell under oxygen/hydrogen gas atmosphere observed by S-K XANES spectroscopy",
abstract = "Changes in the chemical states of the sulfonic groups of Nafion in a model polymer electrolyte fuel cell under an oxygen/hydrogen gas atmosphere were studied using sulfur K-edge XANES spectroscopy. First, the chemical state changes in the sulfonic acid groups of both cathode and anode electrodes due to humidity under oxygen/hydrogen gas flow were observed. Reversible spectral changes ascribed to the hydration and dehydration of the sulfonic acid group were observed at both electrodes. This result is similar to the experimental results obtained without introducing oxygen (helium/hydrogen). On the anode, some of the sulfonic acid groups were decomposed to atomic sulfur adsorbed on platinum (Sad) and the amount increased with time. On the cathode, the formation of Sad was suppressed under the oxygen atmosphere. Next, the effects of oxygen gas introduction onto Sad were examined. Sad was at once formed on both electrodes under dry conditions without an oxygen supply. By supplying oxygen gas, Sad on the cathode disappears. Therefore, the catalyst of the cathode has the ability to recover against the poisoning Sad, while that on the anode accumulates.",
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AU - Isegawa, Kazuhisa

AU - Kim, Daehyun

AU - Kondoh, Hiroshi

PY - 2018/1/1

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N2 - Changes in the chemical states of the sulfonic groups of Nafion in a model polymer electrolyte fuel cell under an oxygen/hydrogen gas atmosphere were studied using sulfur K-edge XANES spectroscopy. First, the chemical state changes in the sulfonic acid groups of both cathode and anode electrodes due to humidity under oxygen/hydrogen gas flow were observed. Reversible spectral changes ascribed to the hydration and dehydration of the sulfonic acid group were observed at both electrodes. This result is similar to the experimental results obtained without introducing oxygen (helium/hydrogen). On the anode, some of the sulfonic acid groups were decomposed to atomic sulfur adsorbed on platinum (Sad) and the amount increased with time. On the cathode, the formation of Sad was suppressed under the oxygen atmosphere. Next, the effects of oxygen gas introduction onto Sad were examined. Sad was at once formed on both electrodes under dry conditions without an oxygen supply. By supplying oxygen gas, Sad on the cathode disappears. Therefore, the catalyst of the cathode has the ability to recover against the poisoning Sad, while that on the anode accumulates.

AB - Changes in the chemical states of the sulfonic groups of Nafion in a model polymer electrolyte fuel cell under an oxygen/hydrogen gas atmosphere were studied using sulfur K-edge XANES spectroscopy. First, the chemical state changes in the sulfonic acid groups of both cathode and anode electrodes due to humidity under oxygen/hydrogen gas flow were observed. Reversible spectral changes ascribed to the hydration and dehydration of the sulfonic acid group were observed at both electrodes. This result is similar to the experimental results obtained without introducing oxygen (helium/hydrogen). On the anode, some of the sulfonic acid groups were decomposed to atomic sulfur adsorbed on platinum (Sad) and the amount increased with time. On the cathode, the formation of Sad was suppressed under the oxygen atmosphere. Next, the effects of oxygen gas introduction onto Sad were examined. Sad was at once formed on both electrodes under dry conditions without an oxygen supply. By supplying oxygen gas, Sad on the cathode disappears. Therefore, the catalyst of the cathode has the ability to recover against the poisoning Sad, while that on the anode accumulates.

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