High-Performance ZnCo₂O₄@CeO₂ Core@shell Microspheres for\nCatalytic CO Oxidation

Abstract

In this paper, we report a self-assembly\nmethod to synthesize high-quality ZnCo₂O₄@CeO₂ core@shell microspheres with tunable CeO₂ thickness.\nZnCo₂O₄ spheres were first synthesized as the\ncore, followed by a controlled CeO₂ shell coating process.\nThe thickness of CeO₂ shell could be easily tuned by varying\nthe feeding molar ratio of Ce/Co. Transmission electron microscope\n(TEM) images and scanning transmission electron microscope (STEM)\nimage have identified the core@shell structure of these samples. In\nCO oxidation tests these ZnCo₂O₄@CeO₂ core@shell microspheres exhibited promising catalytic performance,\nand the catalytic activity of the best sample is even close to the\ntraditional noble metal-CeO₂ system, attaining 100% CO\nconversion at a relatively low temperature of 200 °C. Cycling\ntests confirm their good stability of these core@shell microspheres\nbesides activity. Their high catalytic performance should be attributed\nto the core@shell structure formation, and moreover further H₂–temperature-programmed reduction (TPR) results revealed\nthe possible synergistic effects between the two components of ZnCo₂O₄ and CeO₂.