Electrochemical behavior of the system ferricyanide-ferrocyanide at a graphite-epoxy composite electrode

Cyclic and direct voltammetry with linear potential sweep has been used for the investigation of the dependence of the reversibility and reduction current in the system Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ on the concentrations of LiCl, NaCl, KCl, and CsCl solutions. The electrode was made of a graphite-epoxy composite and activated by mechanically cutting a surface layer directly in the solution and deactivated by the long-term storage in the air. The selected type of the graphite electrode and the method used to activate its surface provides the reversibility and diffusion control of the electrode process in the system Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ regardless of the composition of the supporting solution. In the case of the deactivated electrode, the degree of irreversibility of this process depends on the form and concentration of metal chloride in the supporting electrolyte and the diffusion transfer is complicated by the adsorption of compounds formed between the ferricyanide and the cation of the supporting solution.