Prussian Blue and Analogous Transition Metal Hexacyanoferrates

6 Prussian Blue and Analogous Transition Metal Hexacyanoferrates 

Although metal hexacyanoferrates (HCFs) cannot be considered RPs, from both a structural and a compositional viewpoint, charge percolation occurs through electron-hopping mechanisms quite similar to those just described. For this reason, these pure inorganic materials are dealt with in the frame of this chapter. 

Ferric HCF, called Prussian blue (PB), can be considered one of the very first materials used to coat bare electrodes with a redox-active film in 1978, Neff [35] reported for the first time the electrochemical behavior of a thin layer of PB, 

The cyclic voltammogram of PB-modified electrodes shows the typical trend reported in Fig. 3.5. 

According to the conclusions in Refs. [39,40], the reversible reduction of PB to Prussian white occurs according to the following reaction  

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