SOME CONSEQUENCES OF THE SIGNIFICANTLY DIFFERENT MOBILITIES OF HYDROPHILIC AND HYDROPHOBIC METAL-COMPLEXES IN PERFLUOROSULFONATED IONOMER COATINGS AN ELECTRODES
Ml. Shi et Fc. Anson, SOME CONSEQUENCES OF THE SIGNIFICANTLY DIFFERENT MOBILITIES OF HYDROPHILIC AND HYDROPHOBIC METAL-COMPLEXES IN PERFLUOROSULFONATED IONOMER COATINGS AN ELECTRODES, Analytical chemistry, 69(14), 1997, pp. 2653-2660
Thin coatings of Nafion on glassy carbon rotating disk electrodes were
saturated with hydrophilic [Ru(NH3)(6)(3+), Co(NH3)(6)(3+)] or hydrop
hobic [Ru(bpy)(3)(2+)] counterions. With both types of counterions, th
e plateau currents obtained when the electrodes were rotated in soluti
ons of the cations matched the currents obtained with the uncoated ele
ctrodes in the same solutions at all accessible rotation rates. The hi
gh rates of cross-coating charge propagation demonstrated by these res
ults involved physical diffusion of the hydrophilic complexes and elec
tron hopping between adjacent, immobile pairs of the hydrophobic compl
exes. The approximate concentration profiles that develop within, and
just outside of, Nafion coatings on disk electrodes that are rotated i
n solutions of electroactive counterions are depicted.