Low-temperature CO oxidation over CeO2 and CeO2@Co3O4 core–shell microspheres

Abstract

Mesoporous CeO₂ core–shell microspheres were obtained by pyrolysis of a Ce–asparagine coordination polymer precursor. Then, upon a sheath-coating process via solvothermal treatment with Co(CH₃COO)₂·4H₂O, Co₃O₄ species were uniformly dispersed on the CeO₂ core–shell microsphere surface to generate the CeO₂@Co₃O₄ composite. When used as catalysts for the oxidation of CO to CO₂, the temperature required for full CO conversion was 280 °C and 170 °C for the core–shell microspheres CeO₂ and CeO₂@Co₃O₄-20 wt%, respectively. The porous structure with a core–shell architecture provided a larger surface area and abundant oxygen vacancies to adsorb and activate the CO molecules, resulting in an enhanced catalytic activity. Moreover, the CeO₂@Co₃O₄ core–shell microspheres could maintain complete CO conversion after 30 h reaction. The enhanced CO conversion performance of the CeO₂@Co₃O₄ core–shell microspheres was ascribed to the synergistic interaction between Co₃O₄ and CeO₂.