Abstract's Details

Unusual Oxygen Coordination on Hydrogenated Pt(111)
Abstract ID	MAT-07
Presenter	Janay MacNaughton
Presentation Type	Poster
Full Author List	J. B. MacNaughton (1), L. Näslund (1), H. Ogasawara (1), T. Anniyev (1), A. Nilsson (1)
Affiliations	(1) Stanford Synchrotron Radiation Laboratory (SSRL)
Category	Materials Science
Abstract	Fuel cells have a bright future as emission free sources of energy. A fundamental understanding of the fuel cell catalysis process is required to target existing manufacturing challenges. Surface science experiments utilizing many techniques such as x-ray photoelectron spectroscopy and x-ray absorption spectroscopy have proven to be an effective means of investigating details of the fuel cell oxygen reduction reaction (ORR). Understanding the ORR reaction in detail is essential to elucidating the origin of significant losses which have been found to occur during the reaction steps. Hydrogen peroxide is formed as a by-product during fuel cell operation and its presence initiates the degradation of the ion exchange membrane. Using surface science experiments we have investigated a potential pathway of peroxide formation on the catalyst surface and found that adsorbed hydrogen plays an important role. The presence of hydrogen on the catalyst surface promotes a transition from molecular oxygen laying flat to tilted-up molecules with respect to the surface plane. We propose that the peroxide formation reaction channel is stimulated by this transition of the oxygen orientation on the surface. Additionally, our preliminary studies further indicate that the tilted-up geometry sterically hinders the activation of oxygen by dissociation on the catalyst surface.
Footnotes
Funding Acknowledgement	This work was supported by the Office of Basic Energy Sciences, U.S. Department of Energy under the auspices of the President's Hydrogen Fuel Initiative. The research was carried out at the Stanford Synchrotron Radiation Laboratory, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy. JBM gratefully acknowledges support from the Natural Sciences and Engineering Research Council of Canada.