Au Nanocube-Directed Fabrication of Au−Pd Core−Shell Nanocrystals with Tetrahexahedral, Concave Octahedral, and Octahedral Structures and Their Electrocatalytic Activity
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- 作者：Chun-Lun Lu ; Kariate Sudhakara Prasad ; Hsin-Lun Wu ; Ja-an Annie Ho ; Michael H. Huang
- 刊名：Journal of the American Chemical Society
- 出版年：2010
- 出版时间：October 20, 2010
- 年：2010
- 卷：132
- 期：41
- 页码：14546-14553
- 全文大小：507K
- 年卷期：v.132,no.41(October 20, 2010)
- ISSN：1520-5126
文摘
In this study, we have successfully developed a facile method for the high-yield fabrication of Au−Pd core−shell heterostructures with an unusual tetrahexahedral (THH) morphology using Au nanocubes as the structure-directing cores. The lattice orientations of the Au nanocubes match those of the Pd shells. Structural analysis establishes that the THH nanocrystals are bounded by high-index {730} facets. A substantial lattice mismatch between Au and Pd, oxidative etching in the presence of chloride and oxygen, the use of cetyltrimethylammonium chloride (CTAC) surfactant, and the reaction temperature (30−60 °C) were identified to be key factors facilitating the formation of the THH core−shell nanocrystals. Intermediate products have also been examined to follow the growth process. By selecting cubic gold cores with sizes of 30−70 nm and varying the volume of the gold core solution used, THH Au−Pd core−shell nanocrystals with continuously adjustable sizes from 56 to 124 nm can be readily obtained. Their UV−vis spectra display progressive red-shifted bands. Interestingly, novel concave octahedral and octahedral Au−Pd core−shell nanocrystals can be prepared by lowering the reaction temperature and prolonging the reaction time. The concave octahedra show depressions on all the {111} faces. Electrocatalytic activity of the three Au−Pd core−shell structures for the oxidation of ethanol has been investigated. The THH nanocrystals with entirely high-index {730} facets were found to exhibit the best electrocatalytic activity. These size-tunable THH Au−Pd core−shell nanocrystals may be valuable for catalyzing other organic reactions.