Core Shell Inversion during Nucleation and Growth of Bimetallic Pt/Ru Nanoparticles

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• 作者：Michael S. Nashner ; Anatoly I. Frenkel ; David Somerville ; Charles W. Hills ; John R. Shapley ; and Ralph G. Nuzzo
• 刊名：Journal of the American Chemical Society
• 出版年：1998
• 出版时间：August 19, 1998
• 年：1998
• 卷：120
• 期：32
• 页码：8093 - 8101
• 全文大小：222K
• 年卷期：v.120,no.32(August 19, 1998)
• ISSN：1520-5126

文摘

The reductive condensation of a carbon-supported molecular cluster precursor, PtRu₅C(CO)₁₆, intoa bimetallic nanoparticle has been followed by using in situ extended X-ray absorption fine structurespectroscopy, temperature-programmed desorption, and scanning transmission electron microscopy. The datareveal that during activation in hydrogen the metal centers associated with the molecular precursor lose thestabilizing CO shell and assume an increasingly metallic electronic character. This support-mediatedcondensation process is highly activated. The incipient Pt-Ru nanoparticles initially form a disordered structureat 473 K in which Pt is found preferentially at the core of the condensing particle. After further high-temperaturetreatment to 673 K, the nanoparticles adopt an inverted structure in which Pt appears preferentially at thesurface of the equilibrated bimetallic nanoparticle.