title: Complementarity between high-energy photoelectron and L-edge spectroscopy for probing the electronic structure of 5d transition metal catalysts.
abstract: We demonstrate the successful use of hard X-ray photoelectron spectroscopy (HAXPES) for selectively probing the platinum partial d-density of states (DOS) in a Pt-Cu nanoparticle catalyst which shows activity superior to pure Pt towards the oxygen-reduction reaction (ORR). The information about occupied Pt d-band states was complemented by Pt L(2)-edge X-ray absorption near-edge spectroscopy (XANES), which probes unoccupied valence states. We found a significant electronic perturbation of the Pt projected d-DOS which was narrowed and shifted to higher binding energy compared to pure platinum. The effect of this electronic structure perturbation on the chemical properties of the nanoparticle surface is discussed in terms of the d-band model. We have thereby demonstrated that the combination of L-edge spectroscopy and HAXPES allows for an experimental derivation of the valence electronic structure in an element-specific way for 5d metal catalysts.
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Rd, Menlo Park, CA 94025, USA.
authors.forename: Toyli
authors.initials: T
authors.lastname: Anniyev
authors.forename: Hirohito
authors.initials: H
authors.lastname: Ogasawara
authors.forename: Mathias P
authors.initials: MP
authors.lastname: Ljungberg
authors.forename: Kjartan T
authors.initials: KT
authors.lastname: Wikfeldt
authors.forename: Janay B
authors.initials: JB
authors.lastname: MacNaughton
authors.forename: Lars-Ake
authors.initials: LA
authors.lastname: Näslund
authors.forename: Uwe
authors.initials: U
authors.lastname: Bergmann
authors.forename: Shirlaine
authors.initials: S
authors.lastname: Koh
authors.forename: Peter
authors.initials: P
authors.lastname: Strasser
authors.forename: Lars G M
authors.initials: LG
authors.lastname: Pettersson
authors.forename: Anders
authors.initials: A
authors.lastname: Nilsson
mesh_terms: D002384:Catalysis; D004583:Electrons; D056951:Photoelectron Spectroscopy; D010984:Platinum / Q000737:chemistry; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D028561:Transition Elements; D010984:Platinum