Facile synthesis of multi-shelled MnO2-Co3O4 hollow spheres with superior catalytic activity for CO oxidation

Nano-oxide hollow structures have a wide range of applications in catalysis, but the preparation of multi-shelled composite oxide hollow structures still presents a major challenge. Herein, well-dispersed multi-shelled MnO2-Co3O4 hollow spheres have been successfully prepared via a facile "Kirkendall effect" method employing carbon spheres as sacrifice templates. The shell of the hollow spheres was constructed by interconnected Co3O4 nanosheets and catkin-like MnO2 nanomds. The interdiffusion of Carbon chain and MnO4- during synthesis could be the possible formation mechanism for the special morphology. Benefiting from the hierarchical porous structure, high surface area and strong synergistic effect between Co3O4 and MnO2 was obtained, the as-prepared Co-Mn composite hollow spheres showed reliably high activity and recycle stability for CO oxidation, achieving the complete CO conversion at 137 degrees C without significant decrease in activity after five cycles and 10h constant-temperature reaction. We believe that this work will provide a new method for the preparation of multi-shell composite hollow spheres.