par Buess Herman, Claudine 
Référence Journal of electroanalytical chemistry and interfacial electrochemistry, 186, 1-2, page (41-50)
Publication Publié, 1985-05
Référence Journal of electroanalytical chemistry and interfacial electrochemistry, 186, 1-2, page (41-50)
Publication Publié, 1985-05
Article révisé par les pairs
| Résumé : | We propose in Part I of the present paper that electrocapillary processes which display discontinuous phase transitions and which are controlled by nucleation and growth mechanisms, can be sufficiently described by the classical theory of nucleation. This theory relates the nucleation rate to the change in the surface Gibbs energy gap Δγ#. However, the experimental verification of this theory raises number of methodological problems. These are now identified and then discussed in terms of the most suitable perturbation to be applied to the system. The recommended procedure involves two steps. Firstly, the measurement of a thermodynamic transition potential Eθ and secondly the analysis of certain charge density transients which are observed at overpotentials relative to Eθ. Depending on the circumstances (nature of the surfactant, type of phase change, programme imposed on the electrode, electrode size) the kinetics of the nucleation and growth of a new phase can be observed in three different transformation regimes: mononucleation, oligonucleation and polynucleation. Each of them requires different methodological and mathematical approaches. Furthermore, artefacts are commonly observed in each case and these may complicate the kinetic analysis. The two most common artefacts are faradaic interference and extraneous nucleation. Methods designed to cope with these are described. It is then shown that extraneous nucleations, far from being a nuisance, can in fact be turned to advantage to measure nucleation and growth rates separately. © 1985. |
