Proceedings of the 9th International Conference on X-Ray Absorption Fine Structure

J. Phys. IV France 7 (1997) C2-887-C2-889
DOI: 10.1051/jp4:1997266

The Catalytic Centre of Transition Metal Chalcogenides vis-à-vis the Oxygen Reduction Reaction : An In Situ Electrochemical EXAFS Study

N. Alonso-Vante¹, M. Fieber-Erdmann², H. Rossner², E. Holub-Krappe², Ch. Giorgetti³, A. Tadjeddine³, E. Dartyge³, A. Fontaine³ and R. Frahm<sup>4

1</sup>  Hahn-Meitner-Institut, Department Solare Energetik CS, Glienicker Str. 100, 14109 Berlin, Germany
²  Hahn-Meitner-Institut, PG Synchrotronstrahlung AS, Glienicker Str. 100, 14109 Berlin, Germany
³  LURE, Bât. 209D, Centre Universitaire Paris-Sud, 91405 Orsay cedex, France
⁴  HASYLAB at DESY, Notkestrasse 85, 22603 Hamburg, Germany

Abstract
The Chevrel type chalcogenide with the stoichiometry Mo_6-xM_xX₈ (M=transition metal, e.g., M_x = Ru₂ ; X=Chalcogene atom, e.g., S, Se) containing octahedral mixed-metal clusters of transition-metal atoms was investigated with respect to the oxygen reduction process in an in situ electrochemical enviroment via the EXAFS technique. The spectra analysis on Ru and Mo edges as a function of applied electrode potential revealed that ruthenium centers were preferentially modified by the presence of oxygen in the electrolyte. The variation in distance between Ru-(Ru, Mo) was more sensitive in oxygen saturated solution as compared to Mo-(Ru, Mo) and Ru-Se.

© EDP Sciences 1997