title: Evidence of the substrate effect in hydrogen electroinsertion into palladium atomic layers by means of in situ surface X-ray diffraction.
abstract: 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.
authors.affiliation: Laboratoire d'Electrochimie et de Physicochimie des Matériaux et des Interfaces, CNRS-Grenoble INP-UJF, 1130 rue de la Piscine, 38402 Saint Martin d'Hères, France.
authors.forename: Chrystelle
authors.initials: C
authors.lastname: Lebouin
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Soldo-Olivier
authors.forename: Eric
authors.initials: E
authors.lastname: Sibert
authors.forename: Maurizio
authors.initials: M
authors.lastname: De Santis
authors.forename: Frédéric
authors.initials: F
authors.lastname: Maillard
authors.forename: René
authors.initials: R
authors.lastname: Faure