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Near-Surface Accumulation of Hydrogen and CO Blocking Effects on a Pd–Au Alloy

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journal contribution
posted on 2016-02-19, 09:26 authored by Shohei Ogura, Michio Okada, Katsuyuki Fukutani
Alloying Pd with Au has remarkable features of enhancement of hydrogen solubility compared to Pd and catalytic activity for reactions such as partial hydrogenation of unsaturated hydrocarbons. A key to understanding these phenomena is clarification of hydrogen behavior in the near-surface region. In the present work, by applying nuclear reaction analysis for high-resolution depth profiling of hydrogen in combination with thermal desorption spectroscopy, we show that hydrogen substantially accumulates in the near-surface region and is absorbed in the bulk of a single-crystal Pd70Au30(110) alloy. We also demonstrate a molecular cap effect of CO, where a small amount of CO adsorption greatly changes the hydrogen absorption and desorption behavior by blocking the entrance/exit channel for hydrogen. These findings lead to understanding and controlling the catalytic activity of the Pd–Au alloy and Pd-related surfaces and also open up a new method to control hydrogen transport across metal surfaces.

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