Shape-controlled synthesis of MnOx–CeO2 oxides and their catalytic performance in NO oxidation

Abstract

MnOx–CeO2 nanocubes and nanorods with the pure fluorite-type ceria crystalline structure have been synthesized, in order to investigate the effect of catalysts shape in NO oxidation. The results indicated that both of the nanomaterials growing from Ce(OH)3 nanorods nuclei, and higher hydrothermal temperature and alkali concentration facilitated the conversion of nanorods to nanocubes. During the synthesis process, manganese ions could incorporate into the ceria lattice without affecting its crystalline structure and growth mechanism. The morphology of this binary oxide determines NO oxidation rate, while the specific reaction rate on the reactive {100} planes was two times higher than that on the {111} planes, due to co-effect of the valence state of manganese ions, surface energy and the ratio of surface lattice oxygen species. The results could provide guidance for understanding of the importance of catalyst design in NO oxidation.