In situ X-ray absorption spectroscopy characterizations of RhxSy for ORR applications

COLL 607

J. M. Ziegelbauer, ziegelbauer.j@neu.edu1, Daniel S. Gatewood, dsg82@gwu.edu2, David E. Ramaker, ramaker@gwu.edu2, A. F. Gullá, a.gulla@etek-inc.com3, and S. Mukerjee, s.mukerjee@neu.edu1. (1) Department of Chemistry and Chemical Biology, Northeastern University, 102 Hurtig Hall, 360 Huntington Avenue, Boston, MA 02115, (2) Department of Chemistry, George Washington University, Corcoran Hall, 725 21st Street, NW, Washington, DC 20052, (3) E-TEK Division, PEMEAS Fuel Cell Technologies, 39 Veronica Avenue, Somerset, NJ 08873
The prototype chalcogenide electrocatalyst RhxSy (E-TEK, Inc.) was probed in situ via a synchrotron-based XANES technique (the "delta mu" technique) to elucidate specific sites and modes of water activation during oxygen reduction reaction. X-ray diffraction and EXAFS revealed a mixture of phases (Rh2S3, Rh3S4, and Rh17S15). Theoretically generated XANES on a variety of geometries of O(H) adsorption on these three phases were compared to the experimental data for the three single phases in addition to the balanced-phase electrocatalyst. We show for the first time the specific adsorption geometries of water/oxo-species (e.g. water activation) for each phase in respect to potential, and observe the synergistic effects on the balanced-phase RhxSy electrocatalyst. This expectedly has important consequences for ORR on alternative chalcogenide materials.

 

Physical and Computational Characterization of Nanostructured Electrocatalysts
2:00 PM-4:20 PM, Thursday, 14 September 2006 Sir Francis Drake -- Empire Room, Oral

Division of Colloid & Surface Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006