Electrochemical Behavior of Hexacyano Iron (III/II) in Frozen Aqueous Electrolytes

Electrochemical studies in phases that have been solidified by freezing were carried out. A 5 mM [Fe(CN)6] -3/-4 [Hexacyano Iron(III/II)] in either aqueous 0.1M KCl or in Agar gel containing 0.1 M KCl Agar were the two phase systems subject to this study. Formation of pristine ice crystals (salt free) in pure aqueous electrolyte explains smaller ΔEp recorded in frozen agar than that in absence of Agar. Furthermore, greater capacitive current was observed in frozen agar compared to that in frozen aqueous electrolyte. The results also indicates that while a liquid-like layer (≈ 4 time the value of √2Dt) is formed in frozen aqueous electrolyte at electrode/ electrolyte interface, opposite observation were recorded in frozen agar electrolyte. This evident from the thin-layer electrochemical outcome generated in frozen electrolyte, and low diffusion coefficient determined under these conditions. Deviations from the liquid state behavior at room temperature were explained on the assumption that freezing created conditions similar to those caused by application of high pressure on liquid electrochemical systems. Some kinetic data related to these systems were determined and recorded.