Electrochemical Studies on the Reduction Behavior of Co2+ in Eutectic NaF-KF Melt

In this work, the electrochemical behavior of cobalt ion was investigated using an inert graphite rod electrode at 1073 K in NaF-KF-CoF2 (1 wt%) molten salt system. Several transient electrochemical techniques, such as cyclic voltammetry, square wave voltammetry, and chronopotentiometry, were used. Results showed that electroreduction of Co2+ to Co is a reversible, one-step, two-electron transfer. The diffusion coefficient of Co2+ was investigated with cyclic voltammetry, square wave voltammetry, and chronopotentiometry, and results from the considered methods exhibited fair agreement. Electrodeposition of cobalt was performed at -0.3 V versus Pt at 1073 K for 4 h in a NaFKF-CoF2 (1 wt%) melt. The deposits were examined using X-ray diffraction and X-ray fluorescence, and results confirmed the obtained deposits as metallic cobalt. The present study aims to provide a theoretical reference for electrolysis of WC-Co hard metal scraps in molten salt.