Revealing the effects of asymmetric M-O-Ce structure on CO oxidation over M(Cu, Mn, Fe, La and Zr)-doped CeO 2 catalysts: Atomic radius and oxygen vacancies

Although CeO 2 catalysts doped with different metal ions can significantly enhance CO activity, the intrinsic relationship between these activities and the catalyst structure is still not clearly understood. In this paper, M(Cu, Mn, Fe, La and Zr)-doped CeO 2 catalysts prepared by aerosol method are used as research targets for CO oxidation. Cu-CeO 2 with the smallest atomic radius ratio has the best redox capacity and more oxygen vacancy content. DFT results show that promoting the interface effect in the presence of Cu-O v -Ce is conducive to enhancing CO adsorption capacity. Operando TPR-DRIFTS-MS results reveal that different types of oxygen species (including M=O, Ce - - O, M-O-Ce, and M -OH) exhibit different reactivity on the surface of Ce-based catalysts. M (Cu, Mn, Fe, La and Zr)=O is more likely to react with CO above 100 degrees C. Ce -- O, M-O-Ce, and M -OH also react with CO to form oxygen vacancies (such as M-O v -Ce and Ce -- O v ) and CO 2 after reaching a certain temperature. Among them, the formation of M-O v -Ce has a positive role in promoting the decomposition of O 2. Importantly, carbonate is the rate -determining step that affects the activation of M-O v -Ce. Monodentate carbonates decompose more easily at low temperatures. These findings reveal a novel doping effect and provide a new idea for the design and development of Ce based catalysts with high CO removal ability.