抄録
Nafion-112 is a membrane applied to PEM(Proton Exchange Membrane) fuel cells. In the recent research for PEM fuel cells, it has been found that their performance is decreased in the presence of ammonia contained in the feed gas of H2. In the pores of Nafion-112, there are side chains terminating in sulfonic acid dissociative groups. In the case where such dissociative groups exist on the solid surface contacting with a solution, electric double layers (EDL) may be formed in the pores of membrane, and then an electro-osmotic flow is generated by applying an electric field. In this work, we have confirmed the generation of an electro-osmotic flow across Nafion-112 membrane in the presence of ammonia. In our experiments, several NH3 solutions and NaOH solutions at different concentrations were prepared in order to measure the electro-osmotic flow rate through the membrane. As the result, the electro-osmotic flow rate was increased with the increasing of the solution pH without showing any appreciable dependency on the cation substance, NH4+ or Na+ contained in the solution. In PEM fuel cells, protons migrate from anode to cathode through the pores of the membrane to generate electric power. We conclude that the decrease in the performance of PEM fuel cells might be caused by the prevention of proton migration due to electro-osmotic flow.
