Nanocrystalline CeO2−δ coated β-MnO2 nanorods with enhanced oxygen transfer property

摘要

In this research, β-MnOnanorods were synthesized by a hydrothermal method, followed by a facile precipitation method to obtain nanocrystalline CeO coated β-MnOnanorods. The as-prepared samples were characterized by XRD, HRTEM, FESEM, XPS and in-situ high-temperature XRD. The HRTEM results show that well dispersed CeO nanocrystals sized about 5 nm were coated on the surface of β-MnO nanorods. The oxygen storage and transfer property of as-synthesized materials were evaluated using TGA under various atmospheres (air, pure N, and 5%H/95%Ar). The TGA results indicate that CeO modification could favour the reduction of Mn to Mn and/or Mn at lower temperature as compared with pure β-MnO nanorods and the physically mixed CeO2-δ-β-MnO2 under low oxygen partial pressure conditions (i.e., pure N, 5%H/95%Ar). Specifically, CeO@β-MnO sample can exhibit 7.5 wt% weight loss between 100 and 400 °C under flowing N and 11.4 wt% weight loss between 100 and 350 °C under flowing 5%H2/95%Ar. During the reduction process under pure N or 5%H/95%Ar condition, the oxygen ions in β-MnO nanorods are expected to be released to the surroundings in the form of O or HO with the coated CeO nanocrystals acting as mediator as inferred from the synergistic effect between the well-interacted CeO nanocrystals and β-MnO nanorods.