title: Pyridine adsorption and diffusion on Pt(111) investigated with density functional theory.
abstract: The adsorption, diffusion, and dissociation of pyridine, C5H5N, on Pt(111) are investigated with van der Waals-corrected density functional theory. An elaborate search for local minima in the adsorption potential energy landscape reveals that the intact pyridine adsorbs with the aromatic ring parallel to the surface. Piecewise interconnections of the local minima in the energy landscape reveal that the most favourable diffusion path for pyridine has a barrier of 0.53 eV. In the preferred path, the pyridine remains parallel to the surface while performing small single rotational steps with a carbon-carbon double bond hinged above a single Pt atom. The origin of the diffusion pathway is discussed in terms of the C2-Pt π-bond being stronger than the corresponding CN-Pt π-bond. The energy barrier and reaction enthalpy for dehydrogenation of adsorbed pyridine into an adsorbed, upright bound α-pyridyl species are calculated to 0.71 eV and 0.18 eV, respectively (both zero-point energy corrected). The calculations are used to rationalize previous experimental observations from the literature for pyridine on Pt(111).
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO), Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
authors.forename: Esben L
authors.initials: EL
authors.lastname: Kolsbjerg
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO), Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Groves
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO), Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
authors.forename: Bjørk
authors.initials: B
authors.lastname: Hammer