Balance of Nanostructure and Bimetallic Interactions in Pt Model Fuel Cell Catalysts: In Situ XAS and DFT Study

Daniel Friebel, Venkatasubramanian Viswanathan, Daniel J. Miller, Toyli Anniyev, Hirohito Ogasawara, Ask H. Larsen, Christopher P. O’Grady, Jens K. Nørskov, Anders Nilsson

Research output: Contribution to journalJournal articleResearchpeer-review


We have studied the effect of nanostructuring in Pt monolayer model electrocatalysts on a Rh(111) single-crystal substrate on the adsorption strength of chemisorbed species. In situ high energy resolution fluorescence detection X-ray absorption spectroscopy at the Pt L3 edge reveals characteristic changes of the shape and intensity of the “white-line” due to chemisorption of atomic hydrogen (Had) at low potentials and oxygen-containing species (O/OHad) at high potentials. On a uniform, two-dimensional Pt monolayer grown by Pt evaporation in ultrahigh vacuum, we observe a significant destabilization of both Had and O/OHad due to strain and ligand effects induced by the underlying Rh(111) substrate. When Pt is deposited via a wet-chemical route, by contrast, three-dimensional Pt islands are formed. In this case, strain and Rh ligand effects are balanced with higher local thickness of the Pt islands as well as higher defect density, shifting H and OH adsorption energies back toward pure Pt. Using density functional theory, we calculate O adsorption energies and corresponding local ORR activities for fcc 3-fold hollow sites with various local geometries that are present in the three-dimensional Pt islands.
Original languageEnglish
JournalJournal of the American Chemical Society
Issue number23
Pages (from-to)9664-9671
Number of pages8
Publication statusPublished - 2012


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