1. A mild and environmentally benign strategy towards hierarchical CeO2/Au nanoparticle assemblies with crystal facet-enhanced catalytic effects for benzyl alcohol aerobic oxidation.
- Author
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Gong, Xia, Liu, Baocang, Zhang, Geng, Xu, Guangran, Zhao, Tuo, Shi, Dichao, Wang, Qin, and Zhang, Jun
- Subjects
GOLD nanoparticles ,BENZYL alcohol ,ALCOHOL oxidation ,REACTIVITY (Chemistry) ,CHEMICAL reactions ,IONIC liquids - Abstract
The exposure of the crystallographic facets of CeO
2 nanocrystals may alter their surface structure and composition, leading to significant discrepancies in their reactivity with respect to catalyzing different reactions. In this paper, a facile strategy of etching hollow CeO2 spheres (@CeO2 ) with a fluorine-containing ionic liquid (IL), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4 ]), under hydrothermal conditions was developed to achieve surface-fluorinated @CeO2 nanoparticles with exposed active high-energy facets, which were further assembled in situ into @CeO2 nanoparticle assemblies. The IL, [Bmim][BF4 ], is believed to play an important role in determining the formation of CeO2 nanoparticles, and the mild release of fluorine species from [Bmim][BF4 ] may account for the surface-fluorination and the exposure of active high-energy facets of CeO2 . The CeO2 nanoparticle assemblies are ideal model materials for studying crystal facet-dependent catalytic behavior. By loading well-dispersed Au nanoparticles via a sol-impregnation method, @CeO2 /Au nanoparticle assemblies were achieved, which showed an enhanced catalytic performance for benzyl alcohol aerobic oxidation. In comparison with @CeO2 /Au nanoparticle assemblies obtained by etching @CeO2 spheres with other fluorine-containing agents, NH4 BF4 , NaBF4 , and NH4 F, under identical reaction conditions, @CeO2 /Au nanoparticle assemblies achieved by etching with [Bmim][BF4 ] exhibited the highest catalytic activity for benzyl alcohol aerobic oxidation. The surface-fluorination and the exposure of active high-energy facets of CeO2 nanoparticles are believed to be responsible for the enhancement of their catalytic activity. This methodology provides a robust strategy to create CeO2 materials with the active high-energy facets exposed and afford model materials for investigating crystal facet-dependent catalytic behavior, which currently represents an exciting issue in the nanocatalysis community. [ABSTRACT FROM AUTHOR]- Published
- 2016
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