Portal de Periódicos da CAPES

Electrochemical kinetics at microelectrodes

1988; Elsevier BV; Volume: 256; Issue: 2 Linguagem: Inglês

10.1016/0022-0728(88)87002-5

2590-2954

Christian Amatore, Bruno. Fosset, Joan E. Bartelt, Mark R. Deakin, R. Mark Wightman,

Analytical Chemistry and Sensors

An analytical formulation (eqns. 27–30) for the increase or decrease of the current in steady-state or quasi-steady-state voltammograms is established for the case where the concentration of the inert electrolyte is low, and thus migration can play a role in the flux of electroactive species. The model is developed for systems with species of equal diffusion coefficients, a situation frequently encountered for most organic, inorganic and organometallic cases investigated in electrochemical kinetic studies. With the exception of the cases where the initial charge of the electroactive species (z) is very close to the number of electrons involved in the charge-transfer reaction (n), the increased participation of migration does not result in a dramatic distortion of the voltammogram. It is also shown that the "transport number correction" i/idif = 1/(1−nt/z) widely employed in the electrochemical literature, which is based on an incorrect manipulation of the transport equation, predicts significantly larger effects than this model except for z = n or ¦z¦⪢¦n|. The predictions of the model are evaluated with experimental cases involving one-electron transfer to organometallic ions. The relevance of the analysis which was developed for chemically reversible charge-transfer reactions is related to more complicated situations.