Electrolytic Reduction of ZnO in the CaCl2-NaCl Molten Salt

Electrolytic reduction technology plays a significant role in industrial metal production. In present work, cyclic voltammetry (CV) and square wave voltammetry (SWV) were applied to study the electrochemical behaviors of ZnO cathode in the CaCl2-NaCl melt at 873 K. During the experiment, we found that the dissolution-electrodeposition mechanism (ZnO = Zn2+ + O2-, Zn2+ + 2e(-) = Zn) dominates the electrolytic reduction of ZnO, and the contribution of the direct-reduction from solid phase (ZnO + 2e(-) = Zn + O2-) is small. Furthermore, the electro-reduction of ZnO was conducted by potentiostatic electrolysis. The peak potential of ZnO to Zn was -0.48 V vs Ag/Ag+. Therefore, the metallic Zn can be obtained at an applied potential of -0.80 V (vs Ag/Ag+). When the applied potential increased to -2.00 V (vs Ag/Ag+), the Zn and CaZn3 alloy were formed simultaneously. The electrolytic products were confirmed by X-ray diffraction (XRD) analysis. This study proved the feasibility of electro-reduction technology to prepare Zn metal through the reduction of ZnO material.

Automated summary

Electrolytic reduction technology is important for industrial metal production. In this study, cyclic voltammetry and square wave voltammetry were used to investigate the electrochemical behaviors of ZnO cathode in a CaCl2-NaCl melt at 873 K. The dissolution-electrodeposition mechanism dominated the electrolytic reduction of ZnO, while direct-reduction from solid phase had a small contribution. Electro-reduction of ZnO was successfully achieved by potentiostatic electrolysis. The feasibility of electro-reduction technology for preparing Zn metal from ZnO material was demonstrated.