We have used Pt L3-edge grazing incidence x-rayabsorption fine structure (GIXAFS) and high energy resolution fluorescencedetection (HERFD) XAS to study Pt-O(H) interactions in a model system for anoxygen reduction electrocatalyst, represented by one Pt monolayer on Rh(111) 0.01M HClO4. The use of a Pt monolayer makes the bulk-penetrating hardx-ray probe surface sensitive and can be realized on a variety of substrates toelucidate the influence of metal-metal interactions and interfacial strain onthe catalytic activity. The HERFD spectra reveal characteristic spectral features ofthe near-edge region which can be theoretically modeled using the FEFF8 code. Theincrease and broadening of the white line in the near-edge absorption spectra,which is commonly observed for Pt electrocatalysts at high potentials, can beexplained with the formation of an ultrathin platinum oxide film with a Pt-Ocoordination environment resembling that of bulk PtO.

In situ grazing incidence X-ray absorption spectroscopy of a Pt-modified Rh(111) electrode

239th National Meeting (2010)

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