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–CuO_<i>x</i> shell develops on the surface of Cu₂O cubes and eventually void cubic core/multishell Cu₂O/CeO₂–CuO_<i>x</i> nanocomposites form; however, a rough CeO₂–CuO_<i>x</i> shell develops on the surface of Cu₂O octahedra, and eventually hollow octahedral CeO₂–CuO_<i>x</i> 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