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

The permeation of hydrogen and oxygen through Nafion ® of different water contents was investigated by an electrochemical monitoring technique utilizing SPE composite electrodes. For both gases, the solubility, c 0 , was very high compared with the value in aqueous solutions and was on the order of 10 −2 mol‐dm −3 . The diffusion constant, , was on the order of 10 −7 cm 2 ‐s −1 , While increased with increasing exchange capacity, c 0 was independent of the capacity. and c 0 were almost independent of the water content of the Nafion. Hydrophobic cations, , decreased . It was concluded that the permeation of gases through Nafion takes place in the intermediate region, which consists of the flexible amorphous part of the polytetrafluoroethylene backbone.