Cyclic Voltammetric Experiment - Simulation Comparisons of the Complex Mechanism Associated with Electrochemical Reduction of Zr4+in LiCl-KCl Eutectic Molten Salt

Nuclear energy increasingly represents an important option for generating largely clean CO 2 -free electricity and zirconium is a fission product that is expected to be present in irradiated fuels. The present investigation addresses the electrochemical reduction of Zr 4+ to Zr o in LiCl - KCl eutectic molten salt in the temperature range 425–550°C using cyclic voltammetry (CV), square-wave voltammetry (SWV) and bulk electrolysis. Simulations of the CV data indicate that the initial reduction proceeds through surface confined steps: Zr 4+* + 2e − ↔ Zr 2+* and Zr 2+* + 2e − ↔ Zr * processes (* adsorbed species) followed by a peak-shaped complex diffusion controlled step that consists of a combination of closely spaced processes associated with the reactions Zr 4+ + 4e − → Zr o and Zr 4+ + 3e − → Zr +* . Zr +* , probably in the form of ZrCl * is then further reduced to Zr o* at even more negative potentials. The simulations provide the first quantitative analysis of the thermodynamics and kinetics of the Zr 4+ reduction in the LiCl-KCl eutectic.