Spectroelectrochemistry of EuCl3 in Four Molten Salt Eutectics; 3 LiCl−NaCl, 3 LiCl−2 KCl,LiCl−RbCl,and 3 LiCl−2 CsCl; at 873 K

Key electrochemical properties affecting pyroprocessing of nuclear fuel were examined in four eutectic melts using Eu^3+/2+ as a representative probe. We report the electrochemical and spectroelectrochemical behavior of EuCl₃ in four molten salt eutectics (3 LiCl?NaCl, 3 LiCl?2 KCl, LiCl?RbCl and 3 LiCl?2 CsCl) at 873 K. Cyclic voltammetry was used to determine the reduction potential for Eu^3+/2+ and the applied potentials for spectroelectrochemistry. Single step chronoabsorptometry and thin‐layer spectroelectrochemistry were used to obtain the number of electrons transferred, reduction potentials and diffusion coefficients for Eu³⁺ in each eutectic melt. The reduction potentials determined by thin‐layer spectroelectrochemistry were essentially the same as those obtained using cyclic voltammetry. The diffusion coefficient for Eu³⁺ was the largest in the 3 LiCl?NaCl melt, showed a negative shift in the 3 LiCl?2 KCl melt, and was the smallest in the LiCl?RbCl and 3 LiCl?2 CsCl eutectic melts. The basic one‐electron reversible electron transfer for Eu^3+/2+ was not affected by melt composition.