Evidence of the substrate effect in hydrogen electroinsertion into palladium atomic layers by means of in situ surface x-ray diffraction

C. Lebouin1, Y. Soldo-Olivier1, E. Sibert1, M. De Santis2,3, F. Maillard1, R. Faure1

1 Laboratoire d'Electrochimie et de Physicochimie des Matériaux et des Interfaces, CNRS-Grenoble INP-UJF, 38402 Saint Martin d'Hères, France
2 Institut Néel, CNRS-UJF, 38042 Grenoble Cedex 9, France
3 Institut für Allgemeine Physik, Technische Universität Wien, 1040 Wien, Austria

Langmuir 25 (2009) 4251-4255

In this work, we report an in situ surface X-ray diffraction study of the hydrogen electroinsertion in a two-monolayer equivalent palladium electrodeposit on Pt(111). The role of chloride in the deposition solution in favoring layer-by-layer film growth is evidenced. Three Pd layers are necessary to describe the deposit structure correctly, but the third-layer occupancy is quite low, equal to about 0.22. As a major result, resistance to hydriding of the two atomic Pd layers closest to the Pt interface is observed, which is linked to a strong effect of the Pt(111) substrate. As a consequence, we observe the lowering of the total hydride stoichiometry compared to bulk Pd. Our measurements also reveal good reversibility of the deposit structure, at least toward one hydrogen insertion-desorption cycle.

Corresponding author: Yvonne Soldo-Olivier.

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