One-pot synthesis of Ce_xZr_1-xO₂ solid solution catalysts for the splitting of CO₂ to CO via thermochemical cycling

A series of CeO₂-ZrO₂ solid solutions with different Ce/Zr molar ratios were synthesized by one-pot evaporation-induced self-assembly (EISA) method and characterized by XRD, Raman spectroscopy, H₂-TPR, XPS, SEM and N₂ sorption. The catalytic activity of CeO₂-ZrO₂ solid solutions in the thermochemical splitting of CO₂ to CO were investigated by thermogravimetric analysis. The results reveal that with the increase of Ce/Zr molar ratio, the catalytic activity of CeO₂-ZrO₂ in CO₂ splitting increases first and then decreases. The Ce_0.5Zr_0.5O₂ solution with a Ce/Zr molar ratio of 1 exhibits high activity in CO₂ splitting, owing to its abundant lattice defects and oxygen vacancies which can promote the oxygen migration. In contrast, the Ce_0.75Zr_0.25O₂ solution with a Ce/Zr molar ratio of 3 shows the best cyclic stability, due to its relatively stable number of oxygen vacancies. Sintering of particles was observed after the cycling reaction, accompanying with the phase separation in the Zr-rich solid solutions, which may influence the catalytic performance of CeO₂-ZrO₂ solid solutions in the CO₂ splitting.