Structure of bicomponent metal-oxide composites synthesized by electron beam irradiation method

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• 作者：Junichiro Kugai ; Toshiharu Moriya ; Satoshi Seino ; Takashi Nakagawa ; Yuji Ohkubo ; Koji Ueno ; Hiroaki Nitani ; Takao A. Yamamoto
• 关键词：Electron beam irradiation ; Radiation-induced reduction ; Aqueous phase synthesis ; Bimetallic nanoparticles ; Metal&ndash ; oxide composite
• 刊名：Journal of Alloys and Compounds
• 出版年：2013
• 出版时间：15 November, 2013
• 年：2013
• 卷：577
• 期：Complete
• 页码：125-130
• 全文大小：931 K

文摘

In order to understand the formation process of metal-oxide composite in an electron beam irradiation method in aqueous phase, the structure and composition of obtained solid were correlated to the synthesis parameters. Transition metal did not precipitate alone by the electron beam irradiation, but they did in the presence of platinum or support. Due to the relatively high reduction potential, copper underwent reduction to metallic state and readily precipitated by forming Pt-Cu alloy and/or copper oxide on solid surface. In the Pt-Cu/CeO₂ system, the structure of Pt-Cu was ruled by two competing factors, growth of alloy nanoparticles promoted by sulfate ion and deposition of metal (alloy) on CeO₂ support with their concomitant partial oxidation. CeO₂ was suggested to immobilize the metals oxidatively before they coalesce. Iron barely formed alloy with Pt, but it directly precipitated on support as oxide without being reduced to metal due to its oxophilicity. Oxide was formed either via reduction to metallic state (for Pt and Cu) or through direct oxygenation or hydroxylation on solid (for Fe). Under the restriction of reduction potential, the size and composition of alloy nanoparticles and the content of oxide phase were drastically modified by support surface property and anion species in the solution.