Home – Home – Jornals – Chemistry for Sustainable Development 2022 number 3

The kinetics and mechanism of hydrogen evolution reaction on Mn₅Si₃ electrode in solutions x M H₂SO₄ + (0.5 - x ) M Na₂SO₄, where x = 0.5, 0.35, 0.20, 0.05, are studied by means of polarization and impedance measurements. It is established on the basis of direct- and alternating-current diagnostic criteria that hydrogen evolution reaction on manganese silicide (Mn₅Si₃) in sulphuric acid electrolyte proceeds via discharge - electrochemical desorption route. Both stages are irreversible, and the transfer coefficients of the stages are not equal. Adsorption of atomic hydrogen is described by the Langmuir isotherm. It is assumed that the hydrogen evolution reaction is complicated by the process of hydrogen absorption by the electrode material, proceeding with kinetic control (within the entire investigated potential range). The effect of a thin oxide film on the kinetics of hydrogen evolution on Mn₅Si₃ is noted at low cathodic polarizations. Keywords: manganese silicide Mn₅Si₃, hydrogen evolution reaction, sulphuric acid electrolyte, impedance