Potential dependence of the electrochemical reaction rate

The distinctive feature of electrochemical kinetics is the strong dependence of reaction rates on the interfacial potential difference. 

As will be discussed in Sect. 4.1, multielectron transfer reactions at electrodes are most likely to occur in a series of single one-electron steps. For the present discussion, a general single n-electron transfer reaction is considered (only one transition state) with n most probably one 

Assuming reaction orders of one for both reactant and product, the forward and backward rates can be expressed as 

In electrode kinetics, concentrations are usually employed rather than activities and thus the rate coefficients include the product of activity coefficients (II yf )- 

At a given net rate of reaction in either direction, the electrical current in the external circuit is 

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Markovic and Ross [46] performed such an analysis for CO2 reduction to methane, based on an extensive set of density functional theory. They calculated the limiting potential at which each step of the reaction becomes exergonic (or downhill in free energy). Limiting potentials represents a measure of the potential dependence of the electrochemical reaction rate, given that each limiting potential indicates the electrical potential at which one... 

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