Formal Redox Potentials and Diffusion Coefficients

Electrochemical techniques can effectively be employed for determining the formal potentials, E10, and the number of electrons transferred, n, of redox reactions, in 

Another means of determining D, provided n is known, relies on the use of the rotating disk electrode (RDE). Based on the pioneering work of Levich [39], the steady state diffusion limiting current, measured at an RDE is given by  

An independent determination of E° and n can be made in some instances, by coupling a thin layer electrochemical cell with UV-visible spectroscopy, as described by Kuwana and Heinemann [40]. In its most common embodiment, such an optically 

Spectroelectrochemical experiments in which the potential sequence is applied in both directions in a repetitive fashion allow an assessment of the stability of the electrogenerated species, which was indeed confirmed for both the Fe(III)TMPyP and Co(III)TMPyP systems. Yet another virtue of this methodology is the expedient preparation and spectroscopic characterization of reduced and oxidized forms of materials without the need for synthesizing often highly reactive and thus difficult to handle species. 

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