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Design and Preparation of MnO2/CeO2–MnO2 Double-Shelled Binary Oxide Hollow Spheres and Their Application in CO Oxidation

Zhang, Jian, Cao, Yidan, Wang, Chang-An, Ran, Rui
ACS Applied Materials & Interfaces 2016 v.8 no.13 pp. 8670-8677
air, annealing, aqueous solutions, carbon, carbon monoxide, catalytic activity, ceric oxide, manganese dioxide, oxidation, potassium permanganate, surface area, synergism
Herein, we designed an extremely facile method to prepare well-defined MnO₂@CeO₂–MnO₂ ball-in-ball binary oxide hollow spheres by employing carbon spheres (CSs) as sacrificial templates. The synthesis process involves a novel self-assembled approach to prepare core–shell CSs@CeO₂ precursor, which would directly react with KMnO₄ aqueous solution to form yolk–shell CSs@MnO₂/CeO₂–MnO₂ precursor in the following step. Well-dispersed Ce–Mn binary oxide with double-shelled hollow sphere structure could be achieved after annealing the precursor in air. The evolution process and formation mechanism of this novel structure were thoroughly studied in this paper. Especially the as-prepared double-shell MnO₂/CeO₂–MnO₂ hollow spheres exhibited enhanced catalytic activity for CO oxidation compared with the pure MnO₂ hollow spheres and pure CeO₂ hollow spheres. We believe the high surface area, hierarchical porous structures, and strong synergistic interaction between CeO₂ and MnO₂ contribute to the excellent catalytic activity. Most importantly, this method could be extended to prepare other transition metal oxides. As an example, triple-shelled Co–Mn composite hollow spheres assembled by ultrathin nanoplates were successfully prepared.