Compositions, Structures, and Catalytic Activities of CeO_2@Cu_2O Nanocomposites Prepared by the Template-Assisted Method

摘要

CeO_2@Cu_2O nanocomposites were prepared from Cu_2O cubes and octahedra by the template-assisted method involving the liquid (Ce(IV))?solid (Cu_2O) interfacial reaction. Their compositions, structures, and catalytic activities in CO oxidation were studied in detail. Under the same reaction conditions, CeO_2@Cu_2O nanocomposites prepared from cubic and octahedral Cu_2O templates exhibit different compositions and structures. With an increasing amount of Ce(IV) reactant, a smooth CeO_2?CuO_x shell develops on the surface of Cu_2O cubes and eventually void cubic core/multishell Cu_2O/CeO_2?CuO_x nanocomposites form; however, a rough CeO_2?CuO_x shell develops on the surface of Cu_2O octahedra, and eventually hollow octahedral CeO_2?CuO_x nanocages form. The formation of different compositions and structures of CeO_2@Cu_2O nanocomposites was correlated with the different exposed crystal planes and surface reactivities of Cu_2O cubes and octahedra. The catalytic activity of CeO_2@Cu_2O nanocomposites in CO oxidation depends on their compositions and structures. The most active CeO_2@Cu_2O nanocomposites become active at 70 °C and achieve a 100% CO conversion at 170 °C. These results broaden the versatility of Cu_2O nanocrystals as the sacrificial template for the fabrication of novel nanocomposites with core/shell and hollow nanostructures and exemplify the morphology effect of Cu_2O nanocrystals in liquid?solid interfacial reactions with respect to the composition, structure, and properties of nanocomposites prepared by the template-assisted method.