Carbon sphere-assisted solution combustion synthesis of porous/hollow structured CeO2-MnOx catalysts

Abstract

Solution combustion and hard template are traditional and classical approaches to synthesize porous and hollow structured metal oxides. However, their combination for the construction of porous/hollow structured bimetal oxides has seldom studied. In this work, a novel modified solution combustion method is proposed to synthesize bimetal oxides, e.g. CeO2-MnOx, in which carbon spheres as hard template are introduced into the solution combustion process. The experimental results reveal that the added carbon spheres not only act as hard template to create hollow spaces after removing them, but also burn off themselves in the solution combustion process, and thus affect the crystallinity and oxidation state of manganese oxide. Importantly, CeO2-MnOx catalyst harvested by using the carbon sphere-assisted solution combustion method exhibits the highest catalytic activity toward CO oxidation, compared with those prepared from traditional solution combustion and traditional hard template method. X-ray photoelectron spectroscopy (XPS) and hydrogen temperature-programmed reduction (H2-TPR) analysis demonstrate that there is a strong interaction between CeO2 and MnOx, which is mainly responsible for its high catalytic activity toward CO oxidation. This work is expected to help us modify the solution combustion and design highly efficient catalysts.