A Simple Method to Establish the Relationship Between the Equilibrium Polarization Resistance and the Elementary Kinetic Parameters of an Electrocatalysed Reaction
A simple and rigorous methodology to establish the relationship between the faradaic equilibrium polarization resistance of an electrocatalytic reaction with the elementary kinetic parameters involved in the reaction mechanism is proposed. It was derived through an alternative method, which avoided the differentiation of the corresponding current-overpotential dependence. This formalism includes the cases where both, reactants and products, exhibit diffusion contributions. It is demonstrated that the equilibrium polarization resistance is the sum of both, faradaic and diffusion, contributions. Each diffusion term has a linear variation with the inverse of the limiting diffusion current density of the species involved. This behavior was exemplified with two different experimental data sets for the hydrogen electrode reaction, obtained on a rotating disc and microelectrodes, respectively.
KeywordsEquilibrium polarization resistance Faradaic and diffusion contributions Equilibrium reaction rate of elementary steps Exchange current density
The authors wish to acknowledge the financial support received from Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT, PICT 2014-2001); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, PIP 0311); and Universidad Nacional del Litoral (UNL, CAI+D 2016 PIC 018LI).
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