Role of acidity on the electrochemistry of Prussian Blue at plain and Nafion film-coated electrodes

Prussian Blue (PB) coated on plain platinum (Pt) shows a redox wave at 0.44 V vs SCE in addition to the two usual redox waves at 0.82 and 0.12 V vs SCE when the electrodes were dipped in acidic KCl solution. PB incorporated into Nafion him-coated on Pt electrode exhibited the same behaviour even in the presence of neutral KCl solution. In acidic KCl, the additional redox wave observed for PB incorporated into Nafion film shifted positively to 0.39 V vs SCE and the peak separation was reduced to 30 mV. The observed additional redox wave for PB coated on plain Pt electrode and incorporated into Nafion film-coated Pt electrodes was assigned to the partial reduction of PB occurring due to the insertion of protons into the film. The effect of various cations on the electrochemistry of PB incorporated into Nafion film-coated electrode was also studied.