Electrochemical behavior of manganese dioxide on a gold electrode

The oxidation of Mn2+ to MnO2 and subsequent reduction of MnO2, on a gold electrode were investigated in H2SO4 solutions. Various experimental conditions, e.g. electrolyte composition, potential scan rate, temperature, and stirring were investigated with the purpose of optimization of the manganese dioxide electrodeposition process. The electrochemical properties of electrodeposited MnO2 on An electrode have been investigated using rotating disc electrode (RDE) and the voltammetry techniques. Scanning electron microscope method was also used to study the structure of the deposit. Not mentioned in previous literature, one additional reduction peak was observed on cyclic voltammograms at the potential of ca. 450 mV. The appearance of this peak strongly depends on the sulfuric acid concentration. A characteristic cross-over on the cathodic branch was observed during cyclic voltammetry, the effect not considered before in the literature. The presence of this loop depends on the number of sweep segments, surface activation, electrolyte composition (pH, Mn2+ concentration), electrode rotation speed and on the temperature. Obtained results were supported with thin layer electrode (TLE) with Nafion(R) as separator. (C) 2003 Elsevier Science B.V. All rights reserved.