CO Oxidation on Colloidal Au0.80Pd0.20鈥揊exOy Dumbbell Nanocrystals

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• 作者：Chandramohan George ; Alessandro Genovese ; Alberto Casu ; Mirko Prato ; Mauro Povia ; Liberato Manna ; Tania Montanari
• 刊名：Nano Letters
• 出版年：2013
• 出版时间：February 13, 2013
• 年：2013
• 卷：13
• 期：2
• 页码：752-757
• 全文大小：355K
• 年卷期：v.13,no.2(February 13, 2013)
• ISSN：1530-6992

文摘

We report a colloidal synthesis of Au_0.80Pd_0.20鈥揊e_xO_y dumbbell nanocrystals (NCs) derived from Au_0.75Pd_0.25 NCs by metal oxide overgrowth. We compared the catalytic activity of the two types of NCs in the CO oxidation reaction (CO + 1/2O₂ 鈫?CO₂), after they had been dispersed on an alumina nanopowder support. In both cases, the surface active sites were identified by means of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The enhanced catalytic performance of the dumbbell NCs (Au_0.80Pd_0.20鈥揊e_xO_y) catalyst over that of the initial Au_0.75Pd_0.25 NCs could be correlated to the presence of the epitaxial connection between the Fe_xO_y and the Au_0.80Pd_0.20 domains (as the main factor). Such connection should result in an electron flow from the metal oxide (Fe_xO_y) domain to the noble metal (Au_0.80Pd_0.20) domain and appears to influence favorably the nature and composition of the catalytically active surface sites of the dumbbells. Our experiments indicate indeed that, when the metal alloy domain is attached to the metal oxide domain (that is, in the dumbbell), surface Pd species are more active than in the case of the initial Au_0.75Pd_0.25 NCs and also Au未鈭?/sup> sites are formed that were not present on the initial Au_0.75Pd_0.25 NCs.

Keywords:

Dumbbell nanocrystals; CO oxidation; electron-transfer; DRIFT spectroscopy; alloy nanocrystals