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

Journal Article · Thu May 31 00:00:00 EDT 2012 · J.Amer.Chem.Soc. 134:9664-9671,2012

DOI:https://doi.org/10.1021/ja3003765· OSTI ID:1043861

Friebel, Daniel; Viswanathan, Venkatasubramanian; Miller, Daniel James; Anniyev, Toyli; Ogasawara, Hirohito; Larsen, Ask Hjorth; O'Grady, Christopher P.; Norskov, Jens K.; Nilsson, Anders

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 L(3) edge reveals characteristic changes of the shape and intensity of the 'white-line' due to chemisorption of atomic hydrogen (H(ad)) at low potentials and oxygen-containing species (O/OH(ad)) at high potentials. On a uniform, two-dimensional Pt monolayer grown by Pt evaporation in ultrahigh vacuum, we observe a significant destabilization of both H(ad) and O/OH(ad) 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.

• Research Organization: SLAC National Accelerator Lab., Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); Lundbeck Foundation, Danish Center for Scientific Computing, Alexander von Humboldt Foundation
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 1043861
• Report Number(s): SLAC-PUB-15039; JACSAT; TRN: US201213%%523
• Journal Information: J.Amer.Chem.Soc. 134:9664-9671,2012, Vol. 134, Issue 23; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTROSCOPY
ADSORPTION
CHEMISORPTION
DEFECTS
DENSITY FUNCTIONAL METHOD
DETECTION
ELECTROCATALYSTS
ENERGY RESOLUTION
EVAPORATION
FLUORESCENCE
HYDROGEN
MONOCRYSTALS
NANOSTRUCTURES
PLATINUM
RHODIUM 111
SHAPE
STRAINS
SUBSTRATES
THICKNESS
X-RAY SPECTROSCOPY
CHEM
MATSCI