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. Yet a graph of valence electron concentration, as function of water content, is steeper than graph of inverse volume. This bring us to conclusion that total number of valence electrons decreases with a water uptake. Protons are blocked in Nafion in ex-situ measurement, since the rest of electric circuit is metal that conducts only electrons. On the other hand, in in-situ measurements electrons are blocked in Nafion due to potential barrier of dipole layer. Order of magnitude of the electron concentration we found is 10^28 m^-3.

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

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