ELECTROCHEMICAL RESPONSES OF BILAYER ELECTRODES WITH PRUSSIAN BLUE AS THE INNER LAYER AND ELECTROACTIVE CATION-INCORPORATED NAFION(R) AS THE OUTER LAYER

Bilayer electrodes with Prussian blue as the 'inner' layer and Nafion(R) as the 'outer' layer allow design of multiple redox centre systems by electrostatic binding of electroactive cations into the outer layer. Whilst the overall electrochemical response is a composite of the Prussian blue and electroactive cation redox waves, the presence of the Prussian blue is proposed to impose a slight morphology change in the Nafion(R) compared with when the inner layer is absent. Thus the electrochemical response for the electrostatic binding of the hydrophilic [Ru(NH3)(6)](3+/2+) redox couple is identical in both cases. In contrast, uptake of the hydrophobic [Os(bpy)(3)](3+/2+) redox couple takes place at a slower rate. For the 1,1'-dimethyl-4,4'-bipyridilium cation/radical cation (MV(2+)/MV(+.)) system, known to be quasi-reversible in Nafion(R), radical cation re-oxidation in the presence of the inner layer occurs over a wide potential range, with complete oxidation only occurring on mediation with electrogenerated Prussian blue.