Laboratoire des Composantes pour Pile à Combustible à Membrane Echangeuse de Protons, CEA Grenoble/DRT/Liten/DEHT/LCPEM, Grenoble, France.
J Phys Chem B. 2011 Nov 10;115(44):12835-44. doi: 10.1021/jp205291f. Epub 2011 Oct 13.
A new method based on hydrogen pump has been developed to measure the electroosmotic drag coefficient in representative PEMFC operating conditions. It allows eliminating the back-flow of water which leads to some errors in the calculation of this coefficient with previously reported electrochemical methods. Measurements have been performed on 50 μm thick Nafion membranes both extruded and recast. Contrary to what has been described in most of previous published works, the electroosmotic drag coefficient decreases as the membrane water content increases. The same trend is observed for temperatures between 25 and 80 °C. For the same membrane water content, the electroosmotic drag coefficient increases with temperature. In the same condition, there is no difference in drag coefficient for extruded Nafion N112 and recast Nafion NRE212. These results are discussed on the basis of the two commonly accepted proton transport mechanisms, namely, Grotthus and vehicular.
一种基于氢泵的新方法已被开发出来，用于在代表性的质子交换膜燃料电池工作条件下测量电动拖曳系数。它可以消除水的回流，这导致了之前报道的电化学方法在计算这个系数时的一些误差。已经在 50μm 厚的挤出和重铸的 Nafion 膜上进行了测量。与之前大多数已发表的工作中所描述的情况相反，电动拖曳系数随着膜含水量的增加而减小。在 25 到 80°C 之间的温度下也观察到了同样的趋势。对于相同的膜含水量，电动拖曳系数随温度升高而增加。在相同条件下，挤出的 Nafion N112 和重铸的 Nafion NRE212 的拖曳系数没有差异。这些结果是基于两种普遍接受的质子传递机制，即 Grotthus 和载流子，进行讨论的。
