AN ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY STUDY OF ELECTRODEPOSITED MANGANESE OXIDE-FILMS IN BORATE BUFFERS

The reduction-oxidation processes and conducting properties of mangane se dioxide films prepared by electrochemical deposition on Pt substrat e were studied in borate/boric acid solutions using electrochemical im pedance spectroscopy (EIS). The characteristic parameters of the film can be determined as a function of the manganese oxide deposition rout ine as well as film thickness by application of transfer function anal ysis using non-linear fit routines. A model developed for thin layer i ntercalation electrodes, which is based on the insertion of protons an d electrons, was used and the diffusion coefficients of protons were c alculated for different manganese oxide thicknesses. The reversible be haviour of the manganese oxides during discharge-charge processes as a function of deposition routines was analyzed. Data obtained under a w ide variety of experimental conditions show that the film generated on Pt substrate behaves as a n-type semiconductor. (C) 1997 Elsevier Sci ence Ltd.