A number of complementary, synergistic advances are reported herein. First, we describe the ‘first-time’ synthesis of ultrathin Ru 2 Co 1 nanowires (NWs) possessing average diameters of 2.3 ± 0.5 nm using a modified surfactant-mediated protocol. Second, we utilize a combination of quantitative EDS, EDS mapping (along with accompanying line-scan profiles), and EXAFS spectroscopy results to probe the local atomic structure of not only novel Ru 2 Co 1 NWs but also ‘control’ samples of analogous ultrathin Ru 1 Pt 1 , Au 1 Ag 1 , Pd 1 Pt 1 , and Pd 1 Pt 9 NWs. We demonstrate that ultrathin NWs possess an atomic-level geometry that is fundamentally dependent upon their intrinsic chemical composition. In the case of the PdPt NW series, EDS mapping data are consistent with the formation of a homogeneous alloy, a finding further corroborated by EXAFS analysis. By contrast, EXAFS analysis results for both Ru 1 Pt 1 and Ru 2 Co 1 imply the generation of homophilic structures in which there is a strong tendency for the clustering of ‘like’ atoms; associated EDS results for Ru 1 Pt 1 convey the same conclusion, namely the production of a heterogeneous structure. Conversely, EDS mappingmore »
Selective hydrogenation of 4-nitrostyrene to 4-nitroethylbenzene catalyzed by Pd@Ru core–shell nanocubes
It is a challenge to selectively hydrogenate 4-nitrostyrene to 4-nitroethylbenzene, due to the similar energy barrier of hydrogenation of the nitro and vinyl groups. Herein, we demonstrate that such selective hydrogenation can be achieved by Pd@Ru core–shell nanocubes that are prepared by epitaxial growth of a face-centered cubic Ru shell on Pd cubes. The core–shell structure of Pd@Ru nanocubes is confirmed by transmission electron microscopy, X-ray diffraction spectroscopy, and elemental mapping measurements. It is found that the electronic structure and hence the catalytic activity of the Pd@Ru nanocubes can be readily modulated by the Ru shell thickness. This is manifested in electrochemical CO stripping measurements where a decrease of CO adsorption energy is observed on Pd@Ru nanocubes with the increase of the Ru shell thickness. Results from this study suggest that deliberate structural engineering can be exploited to prepare bimetallic core–shell nanostructures for highly active and selective hydrogenation of organic molecules with multifunctional moieties.
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- Rare metals
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- National Science Foundation
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