Hydrogen overvoltage at manganese in ammonium-bromide-perchloric solution

Kinetic characteristics of electrochemical hydrogen evolution at manganese rotating disc electrode in ammonium-bromide-perchloric solution at 18, 40, and 60°C are determined (the overvoltage, Tafel slopes, exchange currents, and activation energy). The zero-charge potential is found. Mechanism of the electrode process is suggested. It is shown that S-shaped bends in the polarization curves of hydrogen evolution can be entailed with changes in the electrode surface charge. The overvoltage and current density corresponding to beginning of the activationless range of electrochemical hydrogen evolution are determined.