Activation of Anodic Dissolution of the Mn5Si3 Electrode by Fluoride Ions in a Sulfuric Acid Solution

The anodic dissolution of the Mn 5 Si 3 electrode in 0.5 M H 2 SO 4 + (0.0025–0.05) M NaF solutions is studied by the methods of polarization, capacitance, and impedance measurements. The kinetic order of the reaction of dissolution of silicide with respect to NaF as a function of the potential and the differential capacitance as a function of the potential and the concentration of NaF are calculated. It is shown that the effect of sodium fluoride, which activates the anodic dissolution of Mn 5 Si 3 in a sulfuric acid solution, is associated with a weakening of the passivating effect of oxygen-containing silicon compounds and manganese oxides; with an increase in the concentration of NaF, the role of manganese in the kinetics of anodic processes on silicide increases and the role of silicon decreases. The mechanisms and kinetic laws of the anodic processes taking place on the Mn 5 Si 3 electrode are discussed.