Electrochemical and Thermodynamic Properties of Pr on the Liquid Bi Electrode in LiCl-KCl Eutectic Melt

This work presents the electrochemical behaviors of Pr (III) on a liquid Bi electrode and the formation of Bi-Pr intermetallics in LiCl-KCl eutectic melt. Galvanostatic voltammetry and open circuit chronopotentiometry techniques were employed to determine the apparent standard potential of Pr(III)/Pr couple. The reduction of Pr (III) on the liquid Bi electrode is a one step process with three electrons transferred. The activity coefficient of Pr in liquid Bi was also determined by coulometric titration and in-situ open circuit chronopotentiometry at the temperature range of 723 to 813K. In addition, the signals of five intermetallic compounds corresponding to the Bi-Pr binary phase diagram were successively detected by a series of electrochemical techniques. Thermodynamic properties for the formation of Bi-Pr intermetallic compound were measured by open circuit chronopotentiometry. The activities and partial molar Gibbs free energies of Pr in the two phase coexisting system were obtained, from which the Gibbs free energy, the enthalpy and entropy of formation were also calculated. (C) 2018 The Electrochemical Society.