Highly efficient catalytic soot combustion performance of hierarchically meso-macroporous Co3O4/CeO2 nanosheet monolithic catalysts

Herein, we facilely synthesized the Co3O4/CeO2 nanosheets on monolithic Ni foam (Co/Ce-NS) via the tandem hydrothermal and impregnation methods. The constructed hierarchically meso-macroporous nano-structures increase the soot-catalysts contact chances, and promote mass transfer of gaseous reactants and products in catalytic soot combustion. The deposition of Co3O4 nanoparticles onto CeO2 nanosheets enhances the redox properties of the catalysts, because the Co-Ce interaction generates active surface adsorbed oxygen species for soot combustion. Our results reveal that the adsorbed oxygen species on the Co-Ce interfaces are more active than these on surface CeO2 or Co3O4. The 0.6Co/Ce-NS catalyst with the optimal cobalt loading has more superficial Co2+-□-Ce3+ couples than other catalysts, consequently generating more active surface adsorbed oxygen species for catalytic soot oxidation. The 0.6Co/Ce-NS catalyst exhibits comparable catalytic activity with the 1%Pt/Al2O3 catalyst under the loose contact condition. Moreover, the 0.6Co/Ce-NS catalyst has the excellent thermal stability and water resistance. Therefore, the hierarchically meso-macroporous Co3O4/CeO2 nanosheet monolithic catalysts have potential industrial application in catalytic soot elimination and other related heterogeneous catalytic systems.