Bulter-Volmer equation

For large cathodic current densities smaller than the limiting current density, the deposition overpotential increases with increasing current density and vice versa, according to the Bulter-Volmer equation ... 

Fundamentals of Electrode Reactions (Bulter—Volmer Equation) 35... 

Equation (2.22) or Eqn (2.23) is one of the most important equations in dealing with electrochemical surface reactions, which is called the Bulter—Volmer equation. 

Exchange current density and alternative Bulter—Volmer equation. Based on Eqn (2.22), we can define another important kinetic parameter called the exchange current density ( "), which is either the forward or backward current density when the forward and the backward reaction rates become equal. In other words, the reaction is at the equilibrium state with the oxidant concentration of Cq(0, t) and the reductant concentration of Cr(0, t) ... 

Combining Eqns (2.23) and (2.27), an alternative Bulter—Volmer equation can be obtained as ... 

Overpential and Tafel equation. In Eqn (2.28), the term of E is called the overpotential (77), that is, 7 = F —F , which is used to measure the reversibility of the electrochemical reaction. Overpotential is the driving force of the electrode reaction the larger the overpotential, the faster the electrode reaction rate would be. From Bulter—Volmer Eqn (2.28a), it can be seen that when this overpotential is negative enough. 

This empirical equation can be easily rationalized in the context of a Bulter-Volmer treatment as it stems from the definition of the standard rate constant that... 

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