文献类型：期刊文献

英文题名：Biphasic Pd-Au Alloy Catalyst for Low-Temperature CO Oxidation

作者：Xu, Jing[1];White, Tim[2];Li, Ping[1];He, Chongheng[1];Yu, Jianguo[1];Yuan, Weikang[1];Han, Yi-Fan[1]

机构：[1]E China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[2]Australian Natl Univ, Ctr Adv Microcopy, Canberra, ACT 2601, Australia

年份：2010

卷号：132

期号：30

起止页码：10398

外文期刊名：JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

收录：;EI(收录号：20103113110824);WOS:【SCI-EXPANDED(收录号:WOS:000280456100037)】；

基金：The authors are grateful for the support from the Chinese Education Ministry 111 Project (B08021), the Non-Government International Cooperation Project of Shanghai Ministry of Science and Technology (2010/10230705900), Shanghai PuJiang Talent Program (2010/10PJ1402500) and Fundamental Research Funds for the Centred Universities.

语种：英文

外文关键词：X ray diffraction - Gold alloys - Nanocatalysts - Temperature - Palladium alloys - Gold - Mathematical transformations - Oxidation - Surface defects - X ray photoelectron spectroscopy

摘要：Low-temperature CO oxidation over a compositional series of Pd-Au nanoalloy catalysts supported on silica fume was studied. Except for the pure metals, these materials invariably showed biphasic separation into palladium- and gold-rich components. Performance was optimal for a catalyst of bulk composition Pd4Au1, a mixture of Pd90Au10 (72.5 at. %) and Pd31Au69 (27.5 at. %), that was remarkably active at 300 K and more stable than a pure Au catalyst. For bulk materials dominated by Pd (Pd:Au = 16:1; 8:1; 4:1), the palladium-rich alloy fraction frequently adopted hollow sphere or annular morphology, while the gold-rich crystals were often multiply twinned. Quantitative powder X-ray diffraction (XRD) showed that under the synthesis conditions used, the Au solubility limit in Pd crystals was similar to 12 at. %, while Pd was more soluble in Au (similar to 31 at. %). This was consistent with X-ray photoelectron spectroscopy (XPS), which revealed that the surfaces of Pd-rich alloys were enriched in gold relative to the bulk composition. In situ Fourier transform infrared spectra collected during CO oxidation contained a new band at 2114 cm(-1) (attributed to linear CO-Au/Au-Pd bonds) and reduced intensity of a band at 2090 cm(-1) (arising from a linear CO-Pd bond) with escalating Au content, indicating that the Pd sites became increasingly obscured by Au. High-resolution electron micrographs (HRTEM) of the Pd-rich alloys revealed atomic scale surface defects consistent with this interpretation. These results demonstrate that gold-containing biphasic Pd nanoalloys may be highly durable alternatives for a range of catalytic reactions.