Highly stable, mesoporous mixed lanthanum–cerium oxides with tailored structure and reducibility

Pure and mixed lanthanum and cerium oxides were synthesized via a reverse microemulsion-templated route. This approach yields highly homogeneous and phase-stable mixed oxides with high surface areas across the entire range of La:Ce ratios from pure lanthana to pure ceria. Surprisingly, all mixed oxides show the fluorite crystal structure of ceria, even for 10 lanthanum contents as high as 90%. Varying the La:Ce ratio not only allows tailoring of the oxide morphology (lattice parameter, pore structure, particle size, and surface area), but also results in a fine-tuning of the reducibility of the oxide which can be explained by the creation of oxygen vacancies in the ceria lattice upon La addition. The described approach should be applicable to a broad range of other mixed oxides, and hence opens the path towards functional tailoring of oxide 15 materials, such as rational catalyst design via fine-tuning of redox activity.