Template-free Synthesis of Stable Cobalt Manganese Spinel Hollow Nanostructured Catalysts for Highly Water-Resistant CO Oxidation.

Development of spinel oxides as low-cost and high-efficiency catalysts is highly desirable; however, rational synthesis of efficient and stable spinel systems with precisely controlled structure and components remains challenging. We demonstrate the design of complex nanostructured cobalt-based bimetallic spinel catalysts for low-temperature CO oxidation by a simple template-free method. The self-assembled multi-shelled mesoporous spinel nanostructures provide high surface area (203.5 m2/g) and favorable unique surface chemistry for producing abundant active sites and lead to the creation of robust microsphere configured by 16-nm spinel nanosheets, which achieve satisfactory water-resisting property and catalytic activity. Theoretical models show that O vacancies at exposed {110} facets in cubic spinel phase guarantee the strong adsorption of reactive oxygen species on the surface of catalysts and play a key role in the prevention of deactivation under moisture-rich conditions. The design concept with architecture and composition control can be extended to other mixed transition metal oxide compositions.