Investigation of H² Gas Transport in Recast Nafion Films Coated on Platinum in Hydrogen Saturated 85% Phosphoric Acid

Electrochemical impedance spectroscopy measurements were performed with bare and with recast Nafion film-coated Pt electrodes in hydrogen saturated 85% phosphoric acid in order to determine the effects of the film on the transport properties of hydrogen. The impedance data were fit to a model equivalent circuit using nonlinear regression techniques. Two parallel gas diffusion paths in the Nafion film can be inferred from the data. The diffusion coefficients were estimated for each diffusion path in the film. The concentration of hydrogen in the recast Nafion film was found to be over fifteen times greater than in the surrounding solution.