Facile fabrication of trepang-like CeO₂@MnO₂ nanocomposite with high catalytic activity for soot removal

CeO₂@MnO₂ nanocomposite oxide with trepang-like hierarchical structure was prepared by hydrothermal method followed by calcination using Ce(OH)CO₃ and KMnO₄ as the precursor. The catalyst was characterized by several techniques and investigated for soot oxidation. During the hydrothermal process, KMnO₄ could oxidize Ce(OH)CO₃ into CeO₂, accompanying with the formation of flower-like birnessite attached on the surfaces of the generated CeO₂. These flowers further transformed into short nanorods after calcination, leading to the generation of trepang-like CeO₂@MnO₂ composite material. The introduction of MnO₂ not only enhanced the redox property of catalyst induced by the interaction between Ce and Mn, but also contributed to the emergence of more adsorbed oxygen species, which helped to improve the catalytic activity. Moreover, the generated trepang-like structure of CeO₂@MnO₂, with hollow spindle CeO₂ in the middle and short nanorods MnO₂ on the surfaces, offered extra active sites and enhanced the contact between soot and the catalyst, which could also accelerate the soot oxidation. CeO₂@MnO₂ exhibited good catalytic performance for soot oxidation, with T₅₀ at 373 °C under an atmosphere of 5% O₂/500 ppm NO balanced with N₂. The implementation of this work may offer a new strategy to develop high-performance catalysts for soot removal.