2015年
Hydration structure of strongly bound water on the sulfonic acid group in a Nafion membrane studied by infrared spectroscopy and quantum chemical calculation
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
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- 巻
- 17
- 号
- 14
- 開始ページ
- 8843
- 終了ページ
- 8849
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1039/c5cp00567a
- 出版者・発行元
- ROYAL SOC CHEMISTRY
The hydration structure of the 'strongly bound water' around the sulfonic acid (SA) groups in Nafion, which has recently been revealed by H-1 NMR spectroscopy (Anal. Chem., 2013, 85, 7581), is studied using infrared spectroscopy with the aid of quantum chemical (QC) calculations. During a heated drying process, bulky water is firstly dehydrated, which is followed by the disappearance of the hydronium ion and the appearance of bands that have been assigned to the fully dehydrated species at 140 degrees C. However, a spectral simulation based on QC reveals that the spectrum at 140 degrees C comes from the SA group associated with a single-water molecule via two H-bonds. This implies that a thoroughly dried membrane is unavailable even at 140 degrees C, and the involved water corresponds to the 'strongly bound water.' The QC-analytical results are experimentally confirmed by evolved gas analysis mass spectrometry (EGA-MS). At ca. 300 degrees C, which is the temperature where the SA group is selectively decomposed, the molecular fragment of SO2 is observed accompanying water molecules as expected. This confirms that the last single-water molecule can remain on the SA group until the thermal decomposition.
- リンク情報
- ID情報
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- DOI : 10.1039/c5cp00567a
- ISSN : 1463-9076
- eISSN : 1463-9084
- Web of Science ID : WOS:000351933600036