Abstract: We synthesize the K supported nanosheets-like hydrotalcite-derived CoAlO metal oxide by a facile hydrothermal method, which exhibits the superior catalytic performance for soot combustion. The H₂-TPR results show that the interaction between K and Co leads to the improved redox ability of 5K/CoAlO. The Co_2p XPS results show that the Co²⁺/Co³⁺ ratios get increased after loading K on the CoAlO support. It demonstrates that the K loading promotes the transition of cobalt species from Co³⁺ to Co²⁺, which leads to the generation of oxygen vacancies. The O_1s XPS results show that the O_ads/(O_ads + O_lat) ratio increases after K loading. The soot-TPR results indicate that the interaction between K and Co contributes to the adsorption of gaseous O₂ remarkably. During kinetic experiments, 5K/CoAlO exhibits the high reaction rate per unit mass of catalyst, active oxygen(O^*) amount per unit mass of catalyst and TOF, which demonstrates that the interaction between K and Co improves the intrinsic activities of 5K/CoAlO. In addition, owing to the nanosheets-like morphology of 5K/CoAlO, the soot particulates could be highly dispersed on the nanosheets-like layers of 5K/CoAlO and get more access to active components, which is favorable to soot combustion. In summary, the improved amount of active oxygen species and the increased soot-catalyst contact efficiency guarantee the high soot combustion activity of our K supported CoAlO catalysts. Our work provides a novel approach to designing a highly efficient Co-based hydrotalcite-derived oxides catalyst for catalytic soot combustion.

Key words: Hydrotalcite-derived metal oxide, Interaction between K and Co, Oxygen vacancy, Soot combustion, Nanosheets-like morphology