Author(s)

Friedemann Call, Martin Roeb, Martin Schmücker, Hélène Bru, Daniel Curulla-Ferre, Christian Sattler, Robert Pitz-Paal

German Aerospace Center (DLR), Institute of Material Research, K?ln, Germany.
German Aerospace Center (DLR), Institute of Solar Research, K?ln, Germany.
Total RM—New Energies, La Defense Cedex, Paris, France.

Developing an efficient redox material is crucial for thermochemical cycles that produce solar fuels (e.g. H₂ and CO), enabling a sustainable energy supply. In this study, zirconia-doped cerium oxide (Ce_1-xZr_xO₂) was tested in CO₂-splitting cycles for the production of CO. The impact of the Zr-content on the splitting performance was investigated within the range 0 ≤ x < 0.4. The materials were synthesized via a citrate nitrate auto combustion route and subjected to thermogravimetric experiments. The results indicate that there is an optimal zirconium content, x = 0.15, improving the specific CO₂-splitting performance by 50% compared to pure ceria. Significantly enhanced performance is observed for 0.15 ≤ x ≤ 0.225. Outside this range, the performance decreases to values of pure ceria. These results agree with theoretical studies attributing the improvements to lattice modification. Introducing Zr⁴⁺ into the fluorite structure of ceria compensates for the expansion of the crystal lattice caused by the reduction of Ce⁴⁺ to Ce³⁺. Regarding the reaction conditions, the most efficient composition Ce_0.85Zr_0.15O₂ enhances the required conditions by a temperature of 60 K or one order of magnitude of the partial pressure of oxygen p(O₂) compared to pure ceria. The optimal composition was tested in long-term experiments of one hundred cycles, which revealed declining splitting kinetics.

Water Splitting; CO2 Splitting; Thermochemical Cycle; Ceria; CO; Solar Fuels; Hydrogen; H2; Zirconia; Synthesis Gas

F. Call, M. Roeb, M. Schmücker, H. Bru, D. Curulla-Ferre, C. Sattler and R. Pitz-Paal, "Thermogravimetric Analysis of Zirconia-Doped Ceria for Thermochemical Production of Solar Fuel," American Journal of Analytical Chemistry, Vol. 4 No. 10A, 2013, pp. 37-45. doi: 10.4236/ajac.2013.410A1005.