Abstract
Two-step thermochemical cycles are efficient for producing H2 with solar energy, however, they face challenges with thermal losses at high temperatures needed for metal oxide reduction. This study introduces the first experimental demonstration of a thermo-electrochemical cycle for water splitting using ceria (CeO2). By applying electrical potential CeO2 is reduced at temperatures under 1000 °C, significantly lower than the 1400 °C required in a conventional thermal-only process. This is followed by hydrogen production through re-oxidation with water without additional electrical input. This approach eases the conditions of two-step non-stoichiometric thermochemical cycles, showing CeO2 reduction at 750–950 °C with oxygen partial pressure at 2 ·10−6 bar and achieving reduction extents from 0.002 to 0.01 with 0.75–2 V electrical potential. The study explores pure CeO2 and CeO2-YSZ composites, examining the impact of temperature and electrical potential on the degree of non-stoichiometry and demonstrating cyclability and hydrogen output. Moreover, incorporating a dielectric like YSZ reduces power consumption by two orders of magnitude under similar conditions. This research provides a proof-of-concept for a new thermo-electrochemical cycle, suggesting future exploration for other materials to improve conventional thermochemical cycle operating temperatures.
Perry, J., De la Calle, A., Jones, T. W., Donne, S. W., Coronado, J. M., & Bayon, A. (2025). Thermo-electrochemical hydrogen production based on ceria. International Journal of Hydrogen Energy. https://doi.org/10.1016/j.ijhydene.2025.02.083
