Enhancement of the electrocatalytic O-2 reduction on Pt-Fe alloys

The design of high performance cathode electrocatalysts is essential for po lymer-electrolyte fuel cells, which are now attracting enormous interest as a primary power source for zero-emission electric vehicles. We have discov ered a significant enhancement of electrocatalytic activity of Pt by alloyi ng with Fe, and found a maximum activity at ca. 50% Fe content, which resul ts in 25 times higher activity than pure Pt activity. It was confirmed expe rimentally at Pt-Fe bulk alloys that the alloy catalyst surface consists of a purl Pt skin-layer (<1 nm in thickness) that is modified in the electron ic structure by that of the bulk alloy. The enhancement could be well expla ined by the Sd-vacancy of the surface, but not by Pt interatomic distance o r roughening of the surfaces. (C) 1999 Elsevier Science S.A. All rights res erved.