engleski

Ex-situ measurement of charge carrier concentration in Nafion by Hall effect

There is no controversy regarding the nature of charge carriers in in-situ Nafion processes, but still there is controversy regarding charge carriers in ex-situ processes. Using Hall voltage measurements we have shown that valence electrons rather than protons are charge carriers in ex-situ processes, contrary to wide accepted assumption that protons are charge carriers in Nafion regardless of a process. Concentration of valence electrons decreases with water uptake, but a graph of valence electron concentration, as a function of water content, is steeper than a graph of inverse volume. This brings us to conclusion that the total number of valence electrons decreases with water uptake. Concentration of valence electrons in ex-situ measurements is four orders of magnitude higher than proton concentration in in-situ measurements. In ex- situ measurements on Nafion metallic part of the electric circuit blocks proton propagation. On the other hand, in in-situ measurements electrons are blocked in Nafion due to a potential barrier of dipole layer.

Hall Effect ; PEM Fuel Cells ; Charge Carrier Concentration ; Charge Carrier Transport

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