Reactive gas environment induced structural modification of noble-transition metal alloy nanoparticles

V. Petkov, L. Yang, J. Yin, R. Loukrakpam, S. Shan, B. Wanjala, J. Luo, K. W. Chapman, C. J. Zhong

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Abstract

Noble-transition metal (noble=Pt,Au; transition=Co,Ni,Cu) alloy particles with sizes of about 5 nm have been studied by in situ high-energy x-ray diffraction while subjected to oxidizing (O 2) and reducing (H 2) gas atmospheres at elevated temperatures. The different gas atmospheres do not affect substantially the random alloy, face-centered-cubic structure type of the particles but do affect the way the metal atoms pack together. In an O 2 atmosphere, atoms get extra separated from each other, whereas, in an H 2 atmosphere, they come closer together. The effect is substantial, amounting to 0.1 Å difference in the first neighbor atomic distances, and concurs with a dramatic change of the particle catalytic properties. It is argued that such reactive gas induced "expansion shrinking" is a common phenomenon that may be employed for the engineering of "smart" nanoparticles responding advantageously to envisaged gas environments.

Original languageEnglish
Article number125504
JournalPhysical Review Letters
Volume109
Issue number12
DOIs
StatePublished - Sep 19 2012

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