Electronic effects on the water adsorption behaviour and structure formation on pseudomorphic Pt films on Ru(0001)

•Water adsorption on bimetallic PtRu surfaces was investigated by STM.•Ru(0001) surfaces covered by pseudomorphic, 1–4 monolayer Pt films were studied.•Water uptake kinetics and structure vary distinctly with Pt film thickness.•The adsorbed water structures differ significantly from those reported f...

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Bibliographic Details
Published in:Surface science 2018-10, Vol.676, p.30-38
Main Authors: Schilling, Martin, Brimaud, Sylvain, Behm, R. Jürgen
Format: Article
Language:English
Subjects:
Adsorbates
Adsorbed water
Adsorption
Bimetallic surface
Bimetals
Dimers
Electrodes
Electrolytes
Electronic ligand effect
Electronics
Ligands
PtRu
Ruthenium
STM
Structure formation
Substrates
Surface chemistry
Thickness
Ultrahigh vacuum
Water
Water adsorption
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Summary:•Water adsorption on bimetallic PtRu surfaces was investigated by STM.•Ru(0001) surfaces covered by pseudomorphic, 1–4 monolayer Pt films were studied.•Water uptake kinetics and structure vary distinctly with Pt film thickness.•The adsorbed water structures differ significantly from those reported for Pt(111).•The influence of the Pt film thickness is related to vertical ligand effects. Aiming at a fundamental understanding of the interaction of water with bimetallic electrode surfaces, we have systematically investigated the adsorption behaviour and structure formation of water on structurally well-defined Pt/Ru(0001) surfaces under ultrahigh vacuum (UHV) conditions by scanning tunnelling microscopy (STM). For surfaces consisting of pseudomorphic Pt films with thicknesses between 1 and 4 atomic layers on a Ru(0001) substrate, we find a systematic variation of the adsorbate coverage and structure with increasing thickness of the Pt film, from relatively mobile monomers and dimers over stable hexamers to a contiguous hexagonal adlayer for identical exposures, where the latter structures are suggested to represent different stages of a nucleation and growth process leading to a closed water adlayer on these Pt/Ru(0001) surfaces. The structure of the water adlayer differs significantly from previously reported structures of water monolayers on Pt(111). The results are discussed making use of trends in the adsorption behaviour of similar Pt/Ru(0001) surfaces established in previous experimental and theoretical studies. [Display omitted]
ISSN:0039-6028
1879-2758
DOI:10.1016/j.susc.2017.11.010