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Different Surface Chemistries of Water on Ru{0001}: From Monomer Adsorption to Partially Dissociated Bilayers
 

Summary: Different Surface Chemistries of Water on Ru{0001}: From
Monomer Adsorption to Partially Dissociated Bilayers
A. Michaelides, A. Alavi, and D. A. King*
Contribution from the Department of Chemistry, UniVersity of Cambridge,
Cambridge CB2 1EW, U.K.
Received October 8, 2002 ; E-mail: daksec@ch.cam.ac.uk
Abstract: Density functional theory has been used to perform a comparative theoretical study of the
adsorption and dissociation of H2O monomers and icelike bilayers on Ru{0001}. H2O monomers bind
preferentially at atop sites with an adsorption energy of 0.4 eV/H2O. The main bonding interaction is
through the H2O 1b1 molecular orbital which mixes with Ru dz2 states. The lower-lying set of H2O molecules
in an intact H2O bilayer bond in a similar fashion; the high-lying H2O molecules, however, do not bond
directly with the surface, rather they are held in place through H bonding. The H2O adsorption energy in
intact bilayers is 0.6 eV/H2O and we estimate that H bonding accounts for 70% of this. In agreement
with Feibelman (Science 2002, 295, 99) we find that a partially dissociated OH + H2O overlayer is
energetically favored over pure intact H2O bilayers on the surface. The barrier for the dissociation of a
chemisorbed H2O monomer is 0.8 eV, whereas the barrier to dissociate a H2O incorporated in a bilayer is
just 0.5 eV.
1. Introduction
Water is one of the most plentiful and essential compounds
occurring in nature, which makes its interaction with metal

  

Source: Alavi, Ali - Department of Chemistry, University of Cambridge

 

Collections: Chemistry