Relationship between supporting electrolyte bulkiness and dissociative electron transfer at catalytic and non-catalytic electrodes
Articolo
Data di Pubblicazione:
2013
Citazione:
Relationship between supporting electrolyte bulkiness and dissociative electron transfer at catalytic and non-catalytic electrodes / A. Gennaro, A.A. Isse, E. Giussani, P.R. Mussini, I. Primerano, M. Rossi. - In: ELECTROCHIMICA ACTA. - ISSN 0013-4686. - 89(2013), pp. 52-62. [10.1016/j.electacta.2012.11.013]
Abstract:
Dissociative electron transfers (DETs) involving aryl halides in the presence of supporting electrolytes
with tetraalkylammonium cations TAA+ of different diameters provide a first model case of rationalized
relationship between supporting electrolyte bulkiness effect and DET mechanism.
In non-catalytic conditions, with the molecule reacting at the OHP, increasingly bulkier TAA+ cations
result in increasing double layer (DL) thickness and consequently in increasingly hindered electron tunnelling,
and the reduction peak potentials Ep,DET linearly shift in the negative direction with increasing
cation diameter dTAA+. The linear variation of Ep,DET with dTAA+ is consistent with the distance dependence
of kET for reagents held at fixed distances from the electrode (ln k = ln k0 -
.x). The .Ep,DET/.dTAA+
slope is not constant in the investigated model series, but linearly increases with decreasing parameter,
accounting for the heterogeneous ET step becoming increasingly more determining with respect to the
following C X bond cleavage step (as a consequence of decreasing stability of the * orbital corresponding
to the radical anion). Thus the . parameter in the electron tunnelling equation appears to be strictly
related to the ET activation barrier (in particular, to its relative weight in the overall DET kinetics).
On catalytic Ag electrodes, with the molecule reacting at the IHP, the supporting electrolyte effect is
assumed to depend on the increasingly smaller effective potential difference available to the molecule,
reacting close to the electrode, with increasing double layer thickness. It appears more conspicuous than
in non-catalytic conditions, in spite of the less extreme operating potentials, but consistently with the
increased relative importance of the ET activation barrier at a catalytic electrode.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Aryl halides; Dissociative electron transfer; Electrocatalytic silver electrode; Electron tunnelling; Supporting electrolyte effect
Elenco autori:
A. Gennaro, A.A. Isse, E. Giussani, P.R. Mussini, I. Primerano, M. Rossi
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