Nanostructured cerium oxide: preparation, characterization, and application in energy and environmental catalysis
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unctional Oxides Prospective Article
Nanostructured cerium oxide: preparation, characterization, and application in energy and environmental catalysis Wen-Xiang Tang and Pu-Xian Gao, Nanomaterials Science Laboratory, Department of Materials Science and Engineering & Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136, USA Address all correspondence to Pu-Xian Gao at [email protected] (Received 9 July 2016; accepted 19 October 2016)
Abstract Nanostructured cerium oxide (CeO2) with outstanding physical and chemical properties has attracted extensive interests over the past few decades in environment and energy-related applications. With controllable synthesis of nanostructured CeO2, much more features were technologically brought out from defect chemistry to structure-derived effects. This review highlights recent progress on the synthesis and characterization of nanostructured ceria-based materials as well as the traditional and new applications. Specifically, several typical applications based on the desired ceria nanostructures are focused to showcase the importance of nanostructure-derived effects. Moreover, some challenges and perspectives on the nanostructured ceria are presented, such as defects controlling and retainment, scale-up fabrication, and monolithic devices. Hopefully, this review can provide an improved understanding of nanostructured CeO2 and offer new opportunities to promote the further research and applications in the future.
Introduction Cerium oxide (CeO2) is a typical fluorite-structured compound containing a cubic close-packed array of metal atoms with eight coordinate Ce4+ and four coordinate O2− as shown in Fig. 1(a). The {111} surface is terminated by threefold-coordinated oxygen atoms and sevenfold-coordinated cerium atoms; the {110} surface is terminated by a CeO2 plane with threefold oxygen and sixfold cerium atoms; and the polar {100} surface is terminated by twofold-coordinated oxygen atoms.[1] Significantly, the lattice oxygen in CeO2 can be considerably lost under reducing atmosphere at elevated temperatures to form oxygen vacancies without destructing its fluorite crystal structure. However, the oxygen vacancy could be recovered by exposure to an oxidizing condition. Compared with the {111} plane, the {100} and {110} planes of ceria are more active due to the facile migration of lattice oxygen in these planes.[2–5] The high mobility of oxygen vacancies and the reversible valence couple in Ce4+/Ce3+ make ceria a very important oxygen storage material with a wide array of applications in catalysts, fuel cells, oxygen sensors, and ion batteries. Undoubtedly, as a key material component of exhaust emission controlling system in automobiles, the utilization of CeO2 constitutes its vital economic and technological importance, therefore has attracted significant attention over the past few decades. In this Prospective, we focus on the current research development and understanding of nanostructured CeO2, including synthetic approaches, characterization and app
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