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

Abstract 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.