Analysis of the use of voltammetric results as a steady state approximation to evaluate kinetic parameters of the hydrogen evolution reaction

The use of the voltammetric response jvol(η) of a potentiodynamic sweep at a slow scan rate vs in place of a steady state polarization curve jss(η) for the determination of the kinetic parameters of the hydrogen evolution reaction is analyzed. It is proposed to consider jvol(η,vs)≅jss(η) when the condition 0.99≤jvol(η,vs)/jss(η)≤1.01 is verified in the overpotentials range η ≤ −0.05 V. It has been also established a simple relationship between the maximum admissible scan rate vsmax and the equilibrium polarization resistance Rp. Finally, the application of this criterion on different electrodes is described and discussed.