Mass production of Co₃O₄@CeO₂ core@shell nanowires for catalytic CO oxidation

In this study, Co₃O₄@CeO₂ core@shell nanowires were successfully prepared via thermal decomposition of Co(CO₃)_0.5(OH)·0.11H₂O@CeO₂ core@shell nanowire precursors. As a CO oxidation catalyst, Co₃O₄@CeO₂ shows remarkably enhanced catalytic performance compared to Co₃O₄ nanowires and CeO₂ nanoparticles (NPs), indicating obvious synergistic effects between the two components. It also suggests that the CeO₂ shell coating can effectively prevent Co₃O₄ nanowires from agglomerating, hence effecting a substantial improvement in the structural stability of the Co₃O₄ catalyst. Furthermore, the fabrication of the well-dispersed core@shell structure results in a maximized interface area between Co₃O₄ and CeO₂, as well as a reduced Co₃O₄ size, which may be responsible for the enhanced catalytic activity of Co₃O₄@CeO₂. Further examination revealed that CO oxidation may occur at the interface of Co₃O₄ and CeO₂. The influence of calcination temperatures and the component ratio between Co₃O₄ and CeO₂ were then investigated in detail to determine the catalytic performance of Co₃O₄@CeO₂ core@shell nanowires, the best of which was obtained by calcination at 250 ℃ for 3 h with a Ce molar concentration of about 38.5%. This sample achieved 100% CO conversion at a reduced temperature of 160 ℃. More importantly, more than 2.5 g of the Co₃O₄@CeO₂ core@shell nanowires were produced in one pot by this simple process, which may be beneficial for practical applications as automobile-exhaust gas-treatment catalysts.