Experimental Testing of the Electron Transfer Models

The Butler-Volmer rate law has been used to characterize the kinetics of a considerable number of electrode electron transfers in the framework of various electrochemical techniques. Three figures are usually reported the standard (formal) potential, the standard rate constant, and the transfer coefficient. As discussed earlier, neglecting the transfer coefficient variation with electrode potential at a given scan rate is not too serious a problem, provided that it is borne in mind that the value thus obtained might vary when going to a different scan rate in cyclic voltammetry or, more generally, when the time-window parameter of the method is varied. 

Coming back to solvent reorganization, the reduction of aromatic hydrocarbons in an aprotic solvent such as DMF provides a series of data that may be used for testing the Marcus-Hush model of solvent reorganization13,61-63 

FIGURE 1.21. Reduction of aliphatic 1,2-diones in acetonitrile59 Correlation between the experimental activation free energies and values of the internal reorganization energies 

FIGURE 1.23. Variations of the transfer coefficient with the electrode potential derived from convolutive cyclic voltammetry of the following systems with double layer correction, t-nitrobutane in acetonitrile ( ), r-nitrobutane in DMF ( ), nitrodurene in acetonitrile + 2%H20 (a), nitrodurene in acetonitrile ( ), nitromesitylene in acetonitrile (y). Data from reference 64 and references therein. 

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