title: Change of the work function of platinum electrodes induced by halide adsorption.
abstract: The properties of a halogen-covered platinum(111) surface have been studied by using density functional theory (DFT), because halides are often present at electrochemical electrode/electrolyte interfaces. We focused in particular on the halogen-induced work function change as a function of the coverage of fluorine, chlorine, bromine and iodine. For electronegative adsorbates, an adsorption-induced increase of the work function is usually expected, yet we find a decrease of the work function for Cl, Br and I, which is most prominent at a coverage of approximately 0.25 ML. This coverage-dependent behavior can be explained by assuming a combination of charge transfer and polarization effects on the adsorbate layer. The results are contrasted to the adsorption of fluorine on calcium, a system in which a decrease in the work function is also observed despite a large charge transfer to the halogen adatom.
authors.affiliation: Institute of Theoretical Chemistry, Ulm University, 89069 Ulm, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Gossenberger
authors.affiliation: Institute of Theoretical Chemistry, Ulm University, 89069 Ulm, Germany.
authors.forename: Tanglaw
authors.initials: T
authors.lastname: Roman
authors.affiliation: Helmholtz Institute Ulm (HIU) for Electrochemical Energy Storage, 89069 Ulm, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Forster-Tonigold
authors.affiliation: Institute of Theoretical Chemistry, Ulm University, 89069 Ulm, Germany ; Helmholtz Institute Ulm (HIU) for Electrochemical Energy Storage, 89069 Ulm, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Groß
keywords: density functional theory; ionicity; polarizability; surface dipole; work function