Electrochemical characteristics of an aluminum electrode modified by a palladium hexacyanoferrate film, synthesized by a simple electroless procedure

The use of an aluminum substrate as an electrode and the modification of its surface by means of a thin film of palladium hexacyanoferrate (PdHCF) were developed. The modification conditions of the aluminum surface including the electroless deposition of metallic palladium on the electrode surface from PdCl2 + 25% ammonia solution and chemical derivatization of deposited palladium to the PdHCF film in 0.5 M K-3 [Fe(CN)(6)] + 0.5 M KNO3 + HNO3 solution (pH 1 - 1.5), are described. The modified aluminum electrodes prepared under optimum conditions. show a well-defined redox couple due to the [Pd(II)Fe(III/II) (CN)(6)](1 - 2 -) system. The effects of pH and the alkali metal cation of the supporting electrolyte on the elect rochemical characteristics of the modified electrode were studied in detail. Diffusion coefficients of hydrated alkali metal cations in the film (D) the transfer coefficient (alpha) and the transfer rate constant for electron (k(s)), were calculated in the presence of various alkali metal cations. The very high stability of the modified electrode under various experimental conditions was confirmed. (C) 2002 Elsevier Science B.V. All rights reserved.