Dispersion of Rod-like Particles of Nafion in Salt-Free Water/1-Propanol and Water/Ethanol Solutions

The dispersion of perfluorinated sulfonic acid ionomers in catalyst inks is an important factor controlling the performance of catalyst layers in membrane electrode assemblies of proton exchange membrane fuel cells (PEMFCs). The effect of water/alcohol composition on the dispersion of H-Nafion in wa...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2014-12, Vol.118 (51), p.14922-14928
Main Authors: Yamaguchi, Makoto, Matsunaga, Takuro, Amemiya, Kazuki, Ohira, Akihiro, Hasegawa, Naoki, Shinohara, Kazuhiko, Ando, Masaki, Yoshida, Toshihiko
Format: Article
Language:English
Subjects:
Alcohols
Catalysts
Dispersions
Ethanol
Ethyl alcohol
Fluid dynamics
Hydrodynamics
Nuclear magnetic resonance
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Summary:The dispersion of perfluorinated sulfonic acid ionomers in catalyst inks is an important factor controlling the performance of catalyst layers in membrane electrode assemblies of proton exchange membrane fuel cells (PEMFCs). The effect of water/alcohol composition on the dispersion of H-Nafion in water/1-propanol and water/ethanol solutions was studied by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and 19F nuclear magnetic resonance (19F NMR) spectroscopy. Hydrodynamic radii calculated from DLS decay profiles and the radii and interparticle distance of rod-like particles derived from SAXS profiles showed almost the same dependence on alcohol concentration. 1-Propanol was more effective than ethanol to induce changes in the characteristic lengths of the rod-like particles. The motional narrowing in the 19F NMR spectra by addition of 1-propanol indicates selective solvation of the rod-like particles. We suppose this might have decreased their radii and induced their elongation, which eventually led to extension of the ordered regions as observed in the hydrodynamic radii. Our study helps to clarify the dispersion of Nafion in aqueous alcohol solutions, which has implications for the performance of PEMFCs.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp506814m