Étude par analyse de l'impédance cathodique des processus élémentaires de la croissance cristalline d'un dépôt électrolytique
Résumé
In the case of copper electrocystallisation, analysis of the impedance diagram, at very low frequencies, leads to a value of a diffusion coefficient D, in agreement with the value found from the limiting current. This confirms that we are dealing with the transport of Cu2+ ions through the diffusion layer.
As for nickel, electrocrystallisation is shown to occur in two successive reactions, where (NiOH) acts as an adsorbed intermediate consumed at the electrode. Addition of inhibitors such as an acetylenic alcohol or an alkali-metal sulhonate to the electrolyte changes the kinetic parameters of these two successive reactions, and decreases the electrochemical double-layer capacity.