Elementary reaction rates of the hydrogen electrode reaction on nickel analyzed by means of deuterium tracer—II: The cathodic region

The rates of the constituent steps of the hydrogen electrode reaction on nickel were determined under cathodic polarization by means of deuterium tracer. The discharge—recombination reaction route was substantiated. Logarithm of the rate of the process 2H(a) → H₂ was dependent upon the overpotential component shared by the very step with the slope of 30 mV, or the rate was proportional to the square of activity of H(a), whereas that the process H₂ → 2H(a) was independent of it. Logarithm of the rate of formation of H(a) from the solution phase was dependent upon the total overpotential with the slope of ca 100 mV. Dependences of the mechanism and the step rates upon hydrogen pressure were discussed.