Laboratorio de Fisicoquímica, Departamento de Química e Ingeniería Quimica, Universidad Nacional del Sur “Dr. Miguel López Frances”, Bahía Blanca, Argentina
Abstract:
The cathodic decomposition of AgI was studied using a single pulse galvanostatic technique. The working electrode was an AgI-rotating disc immersed in the molten KNO3-NaNO3 eutectic. Linear overpotential-log (current density) plots were obtained for varying concentrations of I−. Evidence was found for the existence of two different control steps, depending on the iodide concentration. At lower I− concentrations a chemical reaction forming an adsorbed AgI−2 complex ion is postulated as the rate-determining step. At higher I− concentrations the rds is related to the electrochemical reaction AgI + e = Ag° + I−. An alternative charge transfer process is suggested corresponding to the transfer of an I− ion between the two ionic media.