Ceria Doped with Zirconium and Lanthanide Oxides to Enhance Solar Thermochemical Production of Fuels

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, the effects of varying the rare-earth content y in Ce0.85-yZr0.15REyO2–0.5y with RE = Y, La, Sm and Gd on the fuel productivity and long-term stability were investigated. Compared to the none-RE-doped reference material, Ce0.85Zr0.15O2, none of the compositions exhibits higher performances. However, long-term cycling of more than 80 cycles reveals enhanced performance due to rare-earth doping. Ce0.85Zr0.15O2 suffers from linear degradation of the yields and of the CO:O2 ratio r, which is attributed to declining oxidation kinetics, whereas for instance Ce0.82Zr0.15Sm0.03O1.99 features stable yields and kinetics. The suggested rationale behind is found in a vacancy-depleted region that occurs in the grains of Ce0.85Zr0.15O2. While cycling, the specific surface decreases and the impact of these regions on the reaction rate increases which...