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C. Lebouin, Y. Soldo-Olivier, E. Sibert, M. De Santis, R. Faure:
"Evidence of the Substrate Effect in Hydrogen Electroinsertion into Palladium Atomic Layers by Means of in Situ Surface X-ray Diffraction";
Langmuir, 25(8) (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.