Gas Permeation in SPE Method: II . Oxygen and Hydrogen Permeation Through Nafion

Abstract

The permeation of hydrogen and oxygen through Nation | of different water contents was investigated by an elec- trochemical monitoring technique utilizing SPE composite electrodes. For both gases, the solubility, c ~ was very high compared with the value in aqueous solutions and was on the order of 10 -2 tool-din -3, The diffusion constant, D, was on the order of 10 -7 cm~-s -'. While D increased with increasing exchange capacity, c o was independent of the capacity. D and c o were almost independent of the water content of the Nation. Hydrophobic cations, R4N § decreased D. It was con- cluded that the permeation of gases through Nation takes place in the intermediate region, which consists of the flexible amorphous part of the polytetrafluoroethylene backbone.