Crossed ferric oxide nanosheets supported cobalt oxide on 3-dimensional macroporous Ni foam substrate used for diesel soot elimination under self-capture contact mode

Abstract

Crossed Fe₂O₃ nanosheets supported cobalt oxide nanoparticles on three-dimensionally macroporous nickel foam substrate (xCo/Fe-NF) was designed and successfully prepared through a facile hydrothermal and impregnation route. These catalysts showed high catalytic soot combustion activities under self-capture contact mode. The three-dimensional macroporous structures of Ni foam and the crossed Fe₂O₃ nanosheets constituted macroporous voids can greatly increase the contact efficiency between soot particulates and catalysts. The interaction between Co and Fe facilitated the activation of the Fe–O bond and increased the amounts of active oxygen species, thus improving the redox property of the catalysts. The 0.6Co/Fe-NF catalyst exhibited the highest turnover frequency (TOF) for soot combustion, which is in good accordance with the largest amount of active oxygen species. Based upon the catalytic performance and multiple characterization results, two reaction pathways for soot oxidation are identified, namely, the direct oxidation by the activated oxygen species via oxygen vacancies and the NO_x-aided soot oxidation.