Effect of copper contamination at the cathode in Cu-Cl electrolyzers for hydrogen production

Abstract

In this work the effects of copper contamination on the coulombic and voltage efficiency of the hydrogen evolution reaction (HER) via the Cu-Cl thermochemical cycle are investigated. A novel proton pump configuration was employed, which allowed for the copper concentration at the cathode to be controlled. A variety of electrochemical tests were performed to evaluate the effect of copper on the system. The purpose of this research project was to determine the threshold for copper contamination at the cathode in these Cu-Cl/HCl electrolyzers. Results of electrochemical test show that there is a significant increase in overpotential and a negative impact on HER kinetics with increasing copper concentration in both a chloride rich and chloride-free environment. In both media the Coulombic efficiency remains constant regardless of the concentration of copper in the catholyte. Results suggest that when the concentration of copper is greater than 5 ppm, the effects of copper contamination becomes significant.