High efficiency CuCl electrolyzer for Cu-Cl thermochemical cycle

The Cu-Cl thermochemical cycle is a promising technology for hydrogen production due to moderate temperature requirements and compatibility with commercially demonstrated renewable heat sources, such as the solar power tower. CuCl/HCl electrolysis, the main hydrogen-producing step of the cycle, has been investigated using a newly developed electrolyzer system supplemented by a number of electrochemical characterization techniques. Nafionbased membranes and Pt/C catalysts were used to prepare membrane electrode assemblies for these tests. The anolyte contained 1 to 2 mol·L^-1 CuCl dissolved in 6 mol·L^-1 HCl(aq), and the catholyte was a 6 mol·L ^-1 HCl(aq) solution. The results of the study showed that the applied potential of 0.7 V can produce the current density around 0.5 A·cm ^-2 for a period of 24 hours at a temperature of 80 °C and ambient pressure. The hydrogen production efficiency was found to be at 91-99 % without any decline during the test. No copper deposition was observed after the test on any component of the electrolyzer.