An electrochemical impedance spectroscopy study of electrodeposited manganese oxide films in borate buffers

The reduction-oxidation processes and conducting properties of manganese dioxide films prepared by electrochemical deposition on Pt substrate were studied in borate/boric acid solutions using electrochemical impedance spectroscopy (EIS). The characteristic parameters of the film can be determined as a function of the manganese oxide deposition routine as well as film thickness by application of transfer function analysis using non-linear fit routines. A model developed for thin layer intercalation electrodes, which is based on the insertion of protons and electrons, was used and the diffusion coefficients of protons were calculated for different manganese oxide thicknesses. The reversible behaviour of the manganese oxides during discharge-charge processes as a function of deposition routines was analyzed. Data obtained under a wide variety of experimental conditions show that the film generated on Pt substrate behaves as a n-type semiconductor. (C) 1997 Elsevier Science Ltd.