AVS 56th International Symposium & Exhibition
    In Situ Microscopy and Spectroscopy: Interfacial and Nanoscale Science Topical Conference Thursday Sessions
       Session IS+SS-ThM

Paper IS+SS-ThM12
Kinetic Studies of the Dissociation of Molecular Oxygen on Pt(111)

Thursday, November 12, 2009, 11:40 am, Room C4

Session: In-Situ Spectroscopy - Interfacial Science & Catalysis
Presenter: D.J. Miller, Stanford Synchrotron Radiation Lightsource
Authors: H. Ogasawara, Stanford Synchrotron Radiation Lightsource
L.-Ǻ. Näslund, Stanford Synchrotron Radiation Lightsource
D.J. Miller, Stanford Synchrotron Radiation Lightsource
T. Anniyev, Stanford Synchrotron Radiation Lightsource
A. Nilsson, Stanford Synchrotron Radiation Lightsource
Correspondent: Click to Email
Thermally programmed X-ray photoelectron spectroscopy was used to study the dissociation of molecular oxygen on Pt(111) under ultrahigh vacuum conditions. Sub-monolayer coverages of molecular oxygen were dosed onto a clean crystal of Pt(111) at 60 K, a temperature well below the dissociation onset of roughly 95 K. Kinetic analysis of the XPS data indicate that they are consistent with a barrier to O2 dissociation that is less than 0.4 eV. This result is in striking contrast to the most recent theoretical studies with density functional theory, which all indicate barriers in excess of 0.5 eV (0.5 - 0.9 eV). On the basis of this low observed barrier, we speculate that the direct dissociation of molecular oxygen could be a viable alternative to the associative and peroxide pathways that are presently assumed to be operative in the oxygen reduction reaction.