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| Title: | The role of negatively charged Au states in aerobic oxidation of alcohols over hydrotalcite supported AuPd nanoclusters |
| Authors: | Nishimura, Shun
Yakita, Yusuke
Katayama, Madoka
Higashimine, Koichi
Ebitania, Kohki |
| Keywords: | AuPd bimatellic catalyst
aerobic oxidatioion of alcohol
reaction mechanism over AuPd catalyst |
| Issue Date: | 2012-05-22 |
| Publisher: | Royal Society of Chemistry |
| Magazine name: | Catalysis Science & Technology |
| Volume: | 3 |
| Number: | 2 |
| Start page: | 351 |
| End page: | 359 |
| DOI: | 10.1039/C2CY20244A |
| Abstract: | The PVP-protected bimetallic gold/palladium nanoclusters (Au_xPd_y-PVP NCs) were prepared onto the solid base hydrotalcite (HT) with various Au:Pd (x:y) molar ratios. Transmission electron microscopy showed narrow particle size distributions of Au_xPd_y-PVP NCs with a mean diameter in the range of 2.6-3.0 nm regardless of Pd contents. Aerobic oxidations of 1-phenylethanol over the Au_xPd_y-PVP/HT catalysts exhibited that their catalytic activities were significantly affected by the Pd contents. Correlations between charge transfer between Au and Pd and catalytic activity of the Au_xPd_y-PVP/HT catalyst were investigated with X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge structure (XANES), Michaelis-Menten kinetic studies for alcohol oxidation, and other analytical techniques. The peaks of Au 4f in the XPS spectra were shifted to lower energy side with increase of Pd content, indicating the electron transfer from Pd to Au atoms according to Pauling's electronegativity protocol. The electron densities in Au 5d orbital in the Au_xPd_y-PVP/HT catalysts estimated by the Au L_3-XANES spectra correlated well with their catalytic activities. Moreover, the kinetic studies also proposed that the electron rich Au 5d states, resulted from the intermetallic electron transfer from Pd atoms, strongly contributed to the rate-determination step in the alcohol oxidation. It was concluded that the electronic negativity in the Au 5d states controlled by the Pd contents accelerated the rate-determination step in alcohol oxidation through highly active radical-like intermediates. |
| Rights: | Copyright (C) 2012 Royal Society of Chemistry. Shun Nishimura,Yusuke Yakita, Madoka Katayama, Koichi Higashimine, Kohki Ebitania, Catalysis Science & Technology, 3(2), 2012, 351-359. http://dx.doi.org/10.1039/C2CY20244A - Reproduced by permission of The Royal Society of Chemistry |
| URI: | http://hdl.handle.net/10119/11599 |
| Material Type: | author |
| Appears in Collections: | c10-1. 雑誌掲載論文 (Journal Articles)
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