Electrochemical behavior of iron-hexacyanoruthenate(II) thin films in aqueous electrolytes: potential analytical and catalytic applications

Electrochemically prepared thin films of iron-hexacyanoruthenate(II) KFex[Ru{CN}6]y or Ruthenium purple (RP) were used as a surface modifier for the glassy carbon electrode (GCE). The redox behavior of the counter/central ions of RP has been investigated in aqueous electrolytes using CV, CC and electrochemical impedance spectroscopy (EIS). The effect of supporting electrolyte components on the electrochemical behavior was also investigated. In aqueous KClO4, RP showed three redox waves with Efo ≈0.2, 0.9 and 1.2 V versus Ag/AgCl. RP thin films were found to be either ionic size discriminatory or very sensitive to the level of doping with some organic solvents. Acetonitrile as a solvent and/or Li+ have a great distorting effect on these redox waves. The potential analytical application of these films was explored. The EC behavior was compared with that of related HCM (hexacyanometalate) compounds, such as KRux[Ru{CN}6]y, KRux[Fe{CN}6]y and KFex[Fe{CN}6]y. Kinetic studies corresponding to the iron and ruthenium centers in RP have been achieved. Obtained results indicated evidence for catalytic behavior of the RP towards water decomposition.