Dual-Templating Preparation and Enhanced Low-Temperature Reducibility of Three-Dimensionally Ordered Macroporous Ceria with Mesoporous Walls

Three-dimensionally ordered macroporous (3DOM) ceria with mesoporous walls and cubic crystal structures were prepared with polymethyl methacrylate (PMMA) as a hard template and triblock copolymer Pluronic F127 (EO(106)PO(70)EO(106)), cetyltrimethylammonium bromide (CTAB), or poly(ethylene glycol) (PEG) as a soft template. Citric acid was used as a complexing agent and cerium nitrate was used as a metal precursor. The 3DOM CeO(2) samples were characterized by numerous analytical techniques. The as-fabricated CeO(2) samples had a 3DOM architecture with polycrystalline wormhole-like mesoporous walls. The nature of the soft template had an important effect on the pore structure and the surface area of the final product. The surface areas of the F127-, CTAB-, and PEG-derived 3DOM CeO(2) samples (denoted CeO(2)-F127, CeO(2)-CTAB, and CeO(2)-PEG, respectively) were ca. 60.5, 60.2, and 51.8 m(2)/g, respectively. The low-temperature reducibility of the 3DOM-structured CeO(2) samples was much better than that of the bulk counterpart and the low-temperature reducibility of the three 3DOM ceria samples increased according to CeO(2)-PEG < CeO(2)-CTAB < CeO(2)-F127, which coincided with the surface oxygen vacancy density sequence. The improved physicochemical properties associated with the formation of the 3DOM skeleton with wormhole-like mesoporous walls may be useful for applications such as CeO(2)-materials in heterogeneous catalysis.