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Less Noble or More Noble: How Strain Affects the Binding of Oxygen on Gold
Author(s) -
Deng Qibo,
Gopal Varun,
Weissmüller Jörg
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201504715
Subject(s) - adsorption , oxygen , surface stress , chemistry , catalysis , noble metal , aqueous solution , strain (injury) , chemical physics , materials science , organic chemistry , surface energy , medicine
Many heterogeneous catalysts exploit strained active layers to modulate reactivity and/or selectivity. It is therefore significant that density functional theory, as well as experimental approaches, find that tensile strain makes the gold surface more binding for oxygen, in other words, less noble. We show that this behavior does not apply when re‐structuring of the gold surface is allowed to occur simultaneously with the adsorption of oxygen. In situ cantilever‐bending studies show the surface stress to increase when oxygen species adsorb on a (111)‐textured gold surface in aqueous H 2 SO 4 . This implies a positive sign of the electrocapillary coupling parameter and, hence, a trend for weaker oxygen binding in response to tensile strain. These conflicting findings indicate that different electrosorption processes, and specifically oxygen species adsorption on the bulk‐terminated surface, exhibit fundamentally different coupling between the chemistry and the mechanics of the surface.