Pt鈥揂u Alloying at the Nanoscale

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• 作者：Valeri Petkov ; Bridgid N. Wanjala ; Rameshwori Loukrakpam ; Jin Luo ; Lefu Yang ; Chuan-Jian Zhong ; Sarvjit Shastri
• 刊名：Nano Letters
• 出版年：2012
• 出版时间：August 8, 2012
• 年：2012
• 卷：12
• 期：8
• 页码：4289-4299
• 全文大小：575K
• 年卷期：v.12,no.8(August 8, 2012)
• ISSN：1530-6992

文摘

The formation of nanosized alloys between a pair of elements, which are largely immiscible in bulk, is examined in the archetypical case of Pt and Au. Element specific resonant high-energy X-ray diffraction experiments coupled to atomic pair distribution functions analysis and computer simulations prove the formation of Pt鈥揂u alloys in particles less than 10 nm in size. In the alloys, Au鈥揂u and Pt鈥揚t bond lengths differing in 0.1 脜 are present leading to extra structural distortions as compared to pure Pt and Au particles. The alloys are found to be stable over a wide range of Pt鈥揂u compositions and temperatures contrary to what current theory predicts. The alloy-type structure of Pt鈥揂u nanoparticles comes along with a high catalytic activity for electrooxidation of methanol making an excellent example of the synergistic effect of alloying at the nanoscale on functional properties.

Keywords:

High-energy resonant XRD; atomic pair distribution functions; reverse Monte Carlo modeling; structure of metallic nanoparticles; catalysis