Redox behaviour and charge transport in solid Berlin green. Microscopic and macroscopic charge diffusion

The electrochemistry of wet solid Berlin green (BG) containing Na+ and K+ has been studied by voltammetry and chronoamperometry. It has been found that the reactions of both electroactive systems in BG, FeII/III cyanide complex and Fe2+/3+, are diffusion controlled. The charge diffusion coefficients in BG containing K+ are high and have been estimated as 2.2 × 10−8 cm2s−1 and 1.1 × 10−7 cm2s−1 under transient and steady-state conditions respectively. Evidence is provided that almost all redox sites in BG are electroactive. BG has been found to be nearly 1:1 mixed hexacyanoferrate(II)/(III).