Nonlinear Potential Dependence of Electrochemical Reaction Rates

Nonlinear Potential Dependence of Electrochemical Reaction Rates 

The expression derived by Despic and Bockris gives a potential dependence of especially when initial- and final-state profiles cross asymmetrically (see Fig. 15), i.e., when AFq is either a large exothermic or endothermic quantity, so that the transition state is, respectively, either close in configuration to the final state or to the initial state. The Tafel relation is consequently nonlinear simulated Tafel relations were calculated showing this behavior. 

From their representation of the origin of a possible potential dependence of p, it is possible to perceive factors, e.g., those that 

Finally, we note here that the representation of the potential dependence of P in the diagram in Despic and Bockris s paper (their Fig. 14) implies ultimately that activationless discharge will set in, as treated by Krishtalik. Then, of course, the process becomes entirely diffusion limited. Correspondingly, barrierless discharge would arise at the other extreme. 

According to the Marcus theory, the electrochemical rate constant ky is written as 

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