267733 Hydrothermal Synthesis of Cerium-Based Mixed Oxide Nanocrystals

Monday, October 29, 2012: 1:20 PM
Butler West (Westin )
Ruigang Wang, Chemistry, Youngstown State University, Youngstown, OH

Hydrothermal Synthesis of Cerium-Based Mixed Oxide Nanocrystals

Ruigang Wang, Samuel I. Mutinda, Varun Sama

Department of Chemistry and Materials Science and Engineering Program,

Youngstown State University, Youngstown, OH 44555

We report a facile hydrothermal synthesis in base solution for shape/size-controlled ceria (CeO2) nanocrystals and Ce-M-O oxide solid solutions (M= Zr, Ti, Pr, Tb etc.). By controlling the crystallization process inspired from the formation of Ce(OH)3 nanocrystal seeds, the morphology of CeO2 could be tuned into different regular shapes such as nanorods, nanocuboids, and nanocubes with reactive {110} and {200} faces, shown in Figure 1. We found that hydrothermal reaction temperature is a critical parameter to control the shape and size of CeO2 nanocrystals. Above 130oC, high resolution transmission electron microscopy studies revealed that the CeO2 nanocubes/nanocuboids expose predominant {200} crystal planes. The compositionally homogeneous Ce-M-O oxide solid solution nanopowders can also readily prepared. Microscopic investigation and catalytic characterization show that the synthesized mixed oxide solid solutions using this method have high crystallinity, and compositional homogeneity, and improved low-temperature reducibility. Reduction treatment of Ce0.5Zr0.5O2 causes a phase transformation, instead of phase separation, from fluoride to pyrochlore structure, suggesting nanoscale compositionally homogeneity of CeO2-ZrO2 nanocrystals. We envision that the synthesis process presented here can be extended to synthesize other cerium-based mixed oxides for use in low-temperature redox active materials in automobile catalytic converter, as well as for catalysis and sensor applications.

Description: F:\Manuscript Plans\2012 ChemCatChem\Figures\Figure 1 Pure CeO2 with different shapes.tif

Figure 1. Some typical morphologies of CeO2 nanoparticles prepared by a facile hydrothermal method at different temperatures: (a): 70C; (b): 90C; (c): 110C; (d): 130C.

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See more of this Session: Nanocrystal Science and Technologies
See more of this Group/Topical: Materials Engineering and Sciences Division