کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
181884 | 459412 | 2007 | 6 صفحه PDF | دانلود رایگان |
The wide degree of scatter of experimental data shows unambiguously that Nafion®117 conductivity is very sensitive to climatic conditions, temperature and relative humidity. In order to allow equilibrium with the surrounding atmosphere to be reached rapidly, a conductivity cell, adapted to a small size membrane samples, has been designed. Conductivity measurements have been carried out by electrochemical impedance spectroscopy (EIS) between 10 °C and 95 °C in a broad domain of relative humidity, i.e., 10–98%. The measurement set up provides reproducible data with a total uncertainty of 30% in a large range of conductivity values. These accurate data enable a power relationship to be proposed at constant temperature between conductivity and relative humidity. This suggests that the solvation process of a sulphonic acid group involves four water molecules. Based on the assumption that a proton mobility depends weakly on temperature, a solvation enthalpy of a sulphonic acid group by water of −135 kJ mol−1 is deduced from conductivity variations with the temperature.
Journal: Electrochemistry Communications - Volume 9, Issue 5, May 2007, Pages 1023–1028