In Situ X-Ray Probing Reveals Fingerprints of Surface Platinum Oxide [electronic resource]

• Ngôn ngữ: eng
• Ký hiệu phân loại: 621.3815 Electrical, magnetic, optical, communications, computer engineering; electronics, lighting
• Thông tin xuất bản: Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2011
• Mô tả vật lý: Medium: ED : , digital, PDF file.
• Bộ sưu tập: Metadata
• ID: 256877
• Chủ đề: 1. 30 direct energy conversion; 2. Absorption; 3. Absorption spectroscopy; 4. Atoms; 5. Bonding; 6. Cathodes; 7. Detection; 8. Electrolytes; 9. Energy resolution; 10. Et al; 11. Fine structure

Tóm tắt

In situ x-ray absorption spectroscopy (XAS) at the Pt L{sub 3} edge is a useful probe for Pt-O interactions at polymer electrolyte membrane fuel cell (PEMFC) cathodes. We show that XAS using the high energy resolution fluorescence detection (HERFD) mode, applied to a well-defined monolayer Pt/Rh(111) sample where the bulk penetrating hard x-rays probe only surface Pt atoms, provides a unique sensitivity to structure and chemical bonding at the Pt-electrolyte interface. Ab initio multiple-scattering calculations using the FEFF8 code and complementary extended x-ray absorption fine structure (EXAFS) results indicate that the commonly observed large increase of the white-line at high electrochemical potentials on PEMFC cathodes originates from platinum oxide formation, whereas previously proposed chemisorbed oxygen-containing species merely give rise to subtle spectral changes.