Effect of the strong metal-support interaction on hydrogen sorption kinetics of Pd-capped switchable mirrors

A. Borgschulte*, R. J. Westerwaal, J. H. Rector, B. Dam, R. Griessen, J. Schoenes

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

37 Citations (Scopus)

Abstract

The morphology and electronic structure of Pd clusters grown on oxidized yttrium surfaces are investigated by scanning tunneling microscopy and ultraviolet photoelectron spectroscopy. The hydrogen sorption mediated by the Pd clusters is determined from the optically monitored switching kinetics of the underlying yttrium film. A strong thickness dependence of the hydrogen uptake is found. The electronic structure of the as-grown Pd clusters depends only weakly on their size. Strong changes of the photoemission spectra are found after hydrogenation, in particular the oxide peak shifts and the Pd peaks vanish. Both phenomena are due to a strong metal-support interaction (SMSI) state, characterized by a complete encapsulation of the clusters by a reduced yttrium oxide layer. Scanning tunneling spectroscopy confirms the SMSI state of small Pd clusters after hydrogen exposure. The SMSI effect is less important with increasing Pd thickness. This explains the critical thickness for the catalyzed hydrogen uptake by the Pd/YOx/Y system. The results shed light on the mechanism of hydrogen absorption at the triple point gas-catalyst-oxide, which also plays an important role in today's fuel cell technology.

Original languageEnglish
Article number155414
Pages (from-to)155414-1-155414-8
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume70
Issue number15
DOIs
Publication statusPublished - Oct 2004

Bibliographical note

Funding Information:
The authors are very grateful to Dr. W. Lohstroh for stimulating discussions. This work is financially supported by the Stichting voor Fundamenteel Onderzoek der Materie (FOM) and the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) through the ACTS program.

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