The rational design of sandwich-like MnO2–Pd–CeO2 hollow spheres with enhanced activity and stability for CO oxidation

Abstract

The development of strategies for the facile fabrication of noble metal/metal oxide nanomaterials with high catalytic activity and thermal stability is very challenging in the field of catalysis and for other relevant applications. Herein, we report a delicate multi-assembly method to prepare sandwich-like MnO₂–Pd–CeO₂ hollow spheres wherein carbon spheres were employed as sacrificial templates. Typically, tiny Pd nanoparticles were deposited on the outer surface of the MnO₂ shell, and the CeO₂ overcoating served as a nanotrap to anchor the Pd particles on the MnO₂ supports. The unique sandwich-like structure effectively prevents the Pd nanoparticles from aggregation during high-temperature calcination and catalyzation. The as-prepared MnO₂–Pd–CeO₂ hollow spheres exhibited enhanced stability and activity for CO oxidation. The excellent stability and activity exhibited by the as-synthesized MnO₂–Pd–CeO₂ hollow spheres can be ascribed to the sandwich-like structure and the strong synergistic effects between Pd and the hierarchical porous MnO₂–CeO₂ shell. We believe that this optimal structure design demonstrates a new approach for the synthesis of noble-metal-based catalysts with superior activity and stability.