NON-STEADY-STATE ROTATING-DISK VOLTAMMETRY OF REDOX COUPLES INCORPORATED IN PERFLUOROSULFONATED IONOMER COATINGS ON ELECTRODES

The differences in the affinity of Nafion coatings for Ru(NH3)(6)(3+/2 +) and Os(bpy)(3)(3+/2+) counterions and the difference in the mobilit ies of the two types of cations within Nafion are used to explain the differences in the voltammetric signatures that they exhibit. A new me thod is proposed with which to determine whether apparent diffusion co efficients of electroactive counterions in electrode coatings differ w hen they are evaluated in transient or in steady-state experiments. Th e utility of non-steady-state cyclic voltammetry with Nafion-coated ro tating disk electrodes to separate the contribution to the observed cu rrent from dissolved and Nafion-confined reactants is demonstrated.