Effect of Hydrophobic Interactions on the Rates of Ionic Diffusion in Nafion Films at Electrode Surfaces.

摘要

Results of studies of diffusional charge transport in films of 1100 and 1200 equivalent weight Nafion on glassy carbon electrode surfaces are reported. A comparison of apparent diffusion coefficients for the oxidized and reduced forms of various ionically diffusing redox couples shows that the ratio of these diffusion coefficients is critically dependent on the nature of the diffusing ion. For hydrophobic redox couples, the diffusion coefficient for the more highly charged form was always greater than the diffusion coefficient for the lower charge form (opposite of what is generally observed in aqueous solution). These results are interpreted in terms of the effect of hydrophobic interactions, with the polymer chain material. (Author)