RESUMO
Effects of morphology and exposed crystal planes of NiOx-decorated CeO2 (NiCeO2) nanostructured catalysts on activity during CO2 methanation were examined, using nanorod (NR), nanocube (NC), and nanooctahedron (NO) structures. The NiCeO2 nanorods (NiCeO2-NR) showed superior activity to NiCeO2-NC and NiCeO2-NO along with excellent selectivity for CH4. This material also demonstrated exceptional durability, with no significant loss of catalytic activity or structural change after use. Comprehensive physicochemical characterization as well as density functional theory calculations determined that the high performance of the NiCeO2-NR was closely related to the large quantity of surface oxygen vacancies and the high degree of reversibility associated with the Ce4+ â Ce3+ redox cycle of the support. These effects originate from the enhanced reactivity of oxygen atoms on the (110) surfaces of the oxide compared with the (100) and (111) surfaces. This information is expected to assist in the rational design of practical catalysts for the activation of CO2 molecules and other important transformations.
