منابع مشابه
State of Water in Perfluorosulfonic Ionomer (Nafion) Proton Exchange Membranes
This manuscript reports on the direct identification of four states of water in hydrated Nafion ionomer polymers, including a quantitative measurement of their dynamics, as previously published in the Journal of the Electrochemical Society, 155, B163-B171 (2008). Here, we provide further details on the dynamics of these water states and we underline still-open scientific questions, towards stim...
متن کاملWater dynamics and proton transfer in nafion fuel cell membranes.
The dynamics of water and its effect on proton transport kinetics in Nafion membranes are compared at several hydration levels. Nafion is the most widely used polyelectrolyte membrane in fuel cells. Ultrafast infrared spectroscopy of the O-D stretch of dilute HOD in H2O provides a probe of the local environment and hydrogen bond network dynamics of water confined in the hydrophilic regions of N...
متن کاملDiffusion and interfacial transport of water in Nafion.
Water absorption, membrane swelling, and self-diffusivity of water in 1100 equivalent weight Nafion were measured as functions of temperature and water activity. Free volume per water at 80 °C, determined from water uptake and volume expansion data, decreases with water content in the membrane from 12 cm(3)/mol at λ = 0.5 H(2)O/SO(3) to 1.5 cm(3)/mol at λ = 4. The change in free volume with wat...
متن کاملMössbauer investigations of Nafion membranes
2014 Mössbauer experiments have been performed on Nafion ion exchange membranes neutralized with iron chloride. The recoilless fraction falls to zero at a temperature which depends on the water content, showing that the rigidity of the local ion environment is greatly influenced by the amount of water retained in these membranes. Two different iron sites are defined, whose relative intensities ...
متن کاملState of Water in Nafion 117 Proton Exchange Membranes Studied by Dielectric Relaxation Spectroscopy
The dynamics and the nature of water environments in a fuel cell proton exchange membrane are studied experimentally. Specifically, the dynamics of water in Nafion 117 membranes, in the acid form, were investigated at two hydration levels and several temperatures by means of dielectric relaxation spectroscopy; two different dielectric spectroscopy experimental setups were employed for low (10-1...
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ژورنال
عنوان ژورنال: Journal of The Electrochemical Society
سال: 2000
ISSN: 0013-4651
DOI: 10.1149/1.1393879