A new method for determining kinetic parameters by simultaneously considering all the independent conditions at an overpotential in case of hydrogen evolution reaction following Volmer–Heyrovsky–Tafel mechanism

Hydrogen evolution reaction following Volmer–Heyrovsky–Tafel mechanism and not under diffusion control can be characterized using Tafel polarization and AC admittance data at various frequencies and at various overpotentials. Such reaction has four independent kinetic parameters. One empirical constant related to charge required for complete surface coverage is also involved. A new approach to determine kinetic parameters utilizing these data and neglecting Heyrovsky and Tafel backward reaction rates has been proposed. This involves determining all the four kinetic constants using experimental data at a single overpotential. The empirical constant, i.e., charge required for complete surface coverage is determined by validating obtained kinetic constants at other overpotentials. The Levenberg–Marquardt algorithm to solve coupled nonlinear equations has been utilized for such purpose. The approach has been validated using the literature data.