Selenium Becomes Metallic in Ru-Se Fuel Cell Catalysts: An EC-NMR and XPS Investigation

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• 作者：Panakkattu K Babu ; Adam Lewera ; Jong Ho Chung ; Ralf Hunger ; Wolfram Jaegermann ; Nicolas Alonso-Vante ; Andrzej Wieckowski ; Eric Oldfield
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：December 12, 2007
• 年：2007
• 卷：129
• 期：49
• 页码：15140 - 15141
• 全文大小：57K
• 年卷期：v.129,no.49(December 12, 2007)
• ISSN：1520-5126

文摘

We report the results of an investigation of the interaction between Se and Ru in Ru-Se electrocatalysts showing high activity and methanol tolerance in the oxygen reduction reaction (ORR). The results of both ⁷⁷Se EC-NMR as well as the XPS measurements indicate that Se, a semiconductor in elemental form, becomes metallic when interacting with Ru in catalysts made both by direct Se deposition onto Ru and from Ru₃(CO)₁₂. The ⁷⁷Se spin-lattice relaxation rates are proportional to T, the Korringa behavior characteristic of metals, an observation supported by the XPS binding energy shift results. The binding energy shifts are proposed to be due to Ru Se charge transfer (resulting in the semiconductor metal transition) which makes Ru less susceptible to oxidation, in the ORR. The results are of general interest since the combined use of EC-NMR and XPS should be applicable to the study of a broad range of other catalysts.