Compositions, structures, and catalytic activities of CeO₂@Cu₂O nanocomposites prepared by the template-assisted method.

Abstract

CeO2@Cu2O nanocomposites were prepared from Cu2O cubes and octahedra by the template-assisted method involving the liquid (Ce(IV))-solid (Cu2O) interfacial reaction. Their compositions, structures, and catalytic activities in CO oxidation were studied in detail. Under the same reaction conditions, CeO2@Cu2O nanocomposites prepared from cubic and octahedral Cu2O templates exhibit different compositions and structures. With an increasing amount of Ce(IV) reactant, a smooth CeO2-CuOx shell develops on the surface of Cu2O cubes and eventually void cubic core/multishell Cu2O/CeO2-CuOx nanocomposites form; however, a rough CeO2-CuOx shell develops on the surface of Cu2O octahedra, and eventually hollow octahedral CeO2-CuOx nanocages form. The formation of different compositions and structures of CeO2@Cu2O nanocomposites was correlated with the different exposed crystal planes and surface reactivities of Cu2O cubes and octahedra. The catalytic activity of CeO2@Cu2O nanocomposites in CO oxidation depends on their compositions and structures. The most active CeO2@Cu2O nanocomposites become active at 70 °C and achieve a 100% CO conversion at 170 °C. These results broaden the versatility of Cu2O nanocrystals as the sacrificial template for the fabrication of novel nanocomposites with core/shell and hollow nanostructures and exemplify the morphology effect of Cu2O nanocrystals in liquid-solid interfacial reactions with respect to the composition, structure, and properties of nanocomposites prepared by the template-assisted method.