Protonic conduction and 1H self-diffusion in nafion film studied by ac conductivity and pulsed field gradient NMR techniques

Abstract

Temperature dependent protonic conductivities σ and 1H self-diffusion coefficients, D, are reported for samples of hydrogen-form NAFION membrane subjected to deionised water and acid pretreatments. Conductivities were measured using ac admittance techniques and self-diffusion coefficients by the pulsed field gradient 1H NMR technique. Acid pretreatment enhanced conductivities by one and a half orders of magnitude, with little change in measured D values. The observed self-diffusion (of neutral species) occurs by a different mechanism to charge (H +) transport.