Morphology Dependence of Catalytic Properties of Ni/CeO₂ Nanostructures for Carbon Dioxide Reforming of Methane

The comparative catalytic activity and coke resistance are examined in carbon dioxide reforming of methane over Ni/CeO2 nanorods (NR) and nanopolyhedra (NP). The Ni/CeO2–NR catalysts display more excellent catalytic activity and higher coke resistance compared with the Ni/CeO2–NP. The high resolution transmission electron microscope reveals that the predominantly exposed planes are the unusually reactive {110} and {100} planes on the CeO2–NR rather than the stable {111} one on the CeO2–NP. The prepared samples were also characterized by X-ray diffraction, transmission electron microscopy, hydrogen temperature-programmed reduction, X-ray photoelectron spectroscopy, UV and visible Raman spectra, and oxygen temperature-programmed oxidation. The {110} and {100} planes show great superiority for the anchoring of Ni nanoparticles, which results in the existence of strong metal–support interaction effect (SMSI). The SMSI effect can be helpful to prevent sintering of Ni particles, which benefits to reduce the deactivation of catalytic activity. Besides, the oxygen vacancies and the mobility of lattice oxygen also show the morphology dependence. They can participate into the catalytic reaction and be beneficial to the activation of carbon deposition. In conclusion, the excellent catalytic activity and coke resistance of the Ni/CeO2–NR should be attributed to the SMSI effect and abundant oxygen vacancies.