title: Controlling Hydrogen Activation, Spillover, and Desorption with Pd-Au Single-Atom Alloys.
abstract: Key descriptors in hydrogenation catalysis are the nature of the active sites for H2 activation and the adsorption strength of H atoms to the surface. Using atomically resolved model systems of dilute Pd-Au surface alloys and density functional theory calculations, we determine key aspects of H2 activation, diffusion, and desorption. Pd monomers in a Au(111) surface catalyze the dissociative adsorption of H2 at temperatures as low as 85 K, a process previously expected to require contiguous Pd sites. H atoms preside at the Pd sites and desorb at temperatures significantly lower than those from pure Pd (175 versus 310 K). This facile H2 activation and weak adsorption of H atom intermediates are key requirements for active and selective hydrogenations. We also demonstrate weak adsorption of CO, a common catalyst poison, which is sufficient to force H atoms to spill over from Pd to Au sites, as evidenced by low-temperature H2 desorption.
authors.affiliation: Department of Chemistry, Tufts University , 62 Talbot Avenue, Medford, Massachusetts 02155, United States.
authors.forename: Felicia R
authors.initials: FR
authors.lastname: Lucci
authors.affiliation: Thomas Young Centre and Department of Chemical Engineering, University College London , Roberts Building, Torrington Place, London WC1E 7JE, United Kingdom.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Darby
authors.affiliation: Department of Chemistry, Tufts University , 62 Talbot Avenue, Medford, Massachusetts 02155, United States.
authors.forename: Michael F G
authors.initials: MF
authors.lastname: Mattera
authors.affiliation: Department of Chemistry, Tufts University , 62 Talbot Avenue, Medford, Massachusetts 02155, United States.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Ivimey
authors.affiliation: Department of Chemistry, Tufts University , 62 Talbot Avenue, Medford, Massachusetts 02155, United States.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Therrien
authors.affiliation: Thomas Young Centre, London Centre for Nanotechnology and Department of Physics and Astronomy, University College London , 17-19 Gordon Street, London WC1H 0AH, United Kingdom.
authors.forename: Angelos
authors.initials: A
authors.lastname: Michaelides
authors.affiliation: Thomas Young Centre and Department of Chemical Engineering, University College London , Roberts Building, Torrington Place, London WC1E 7JE, United Kingdom.
authors.forename: Michail
authors.initials: M
authors.lastname: Stamatakis
authors.affiliation: Department of Chemistry, Tufts University , 62 Talbot Avenue, Medford, Massachusetts 02155, United States.
authors.forename: E Charles H
authors.initials: EC
authors.lastname: Sykes