Preparation and Physical and Electrochemical Properties of Carbon-Supported Pt-Ru (Pt-Ru/C) Samples Using the Polygonal Barrel-Sputtering Method

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• 作者：Mitsuhiro Inoue ; Hiroshi Shingen ; Tomohito Kitami ; Satoshi Akamaru ; Akira Taguchi ; Yasuhisa Kawamoto ; Akio Tada ; Kazuhiko Ohtawa ; Kanji Ohba ; Masao Matsuyama ; Kuniaki Watanabe ; Iwao Tsubone ; Takayuki A
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：February 7, 2008
• 年：2008
• 卷：112
• 期：5
• 页码：1479 - 1492
• 全文大小：974K
• 年卷期：v.112,no.5(February 7, 2008)
• ISSN：1932-7455

文摘

Carbon-supported Pt-Ru alloy (Pt-Ru/C) catalysts were prepared using the "polygonal barrel-sputteringmethod". From the preparation of a Pt-Ru alloy with Pt/Ru = ca. 50:50 atom % on a glass plate as support,the optimum sputtering conditions were an Ar gas pressure of 0.9-0.7 Pa and room temperature. The amountof the sputtered Pt-Ru alloy was controlled by changing the ac power and the sputtering time. Subsequently,the Pt-Ru/C samples were prepared under the given optimum conditions. The Pt-Ru alloy was dispersedextensively in the form of nanoparticles on a carbon support. For the ac power levels of 130, 100, and 50 W,the size distributions were narrower when the ac power was lowered. The respective average particle sizeswere 4.1 nm (130 W), 3.3 nm (100 W), and 2.2 nm (50 W). In the case of 30 W, however, the size distributionand the average particle size were almost identical to those for 50 W. In addition, when the Pt-Ru/C sampleswere prepared by changing the sputtering time, only the dispersion density of the alloy nanoparticles increasedin the Pt and the Ru deposited without changing the particle size. The atomic ratios of Pt and Ru in individualPt-Ru alloy nanoparticles for the prepared samples were similar to the sputtering ratio and homogeneouscompared with those for the commercially available samples. With regard to the electrochemical propertiesfor the prepared samples, the hydrodynamic voltammograms for H₂ oxidation were identical to that of thecommercially available sample. However, for CO oxidation, the peak shapes and the peak potentials for theprepared samples were sharper and ca. 20 mV lower than those for the commercially available samples, dueto the uniform Pt and Ru atomic ratios of the individual alloy particles for the prepared samples. The coulombcharges of the CO oxidation reaction per amount of Pt and Ru for the prepared samples increased linearly inthe reversed average particle sizes, while on the other hand, the charges for the commercially available sampleswere not proportional to the reversed sizes. This shows that the Pt-Ru alloy for the prepared samples wasmore efficiently utilized for electrochemical reactions rather than were the commercial ones. In addition, thecell performances for the alloy loading of 0.08 or 0.02 mg/cm² using the prepared Pt-Ru/C samples weresimilar to those for 0.50 mg/cm² using the commercially available sample.