Electrochemistry of rare earth oxy ions REO+ (RE = Ce, La, Nd) in molten MgCl2–NaCl–KCl eutectic

The electrochemical behaviour of the Ce, La and Nd oxy ions in MgCl2–NaCl–KCl eutectic was studied using cyclic voltammetry, chronopotentiometry, square wave voltammetry and electrochemical impedance spectroscopy. It has been deduced that the lanthanides are present as REOCl (RE = Ce, La, Nd) in the electrolyte and the reduction of oxychloride ion takes place in a single step according to the reaction + 1 e - → REO ( RE = Ce, La, Nd ) duction of REO+ was found to be reversible at lower scan rates but quasi-reversible at higher scan rates beyond 75 mV s−1. The diffusion coefficients of the rare earth oxy ions evaluated using Berzins Delahay equation were comparable and found to be ∼10−5 cm2 s−1. A single cathodic peak was observed in the square wave voltammograms at lower concentrations of the oxy ion but at higher concentrations, an additional peak was observed at a lower cathodic peak potential which is attributable to the adsorption of the product.