Web Release Date: February 20,
Electrocatalytic Reduction of Oxygen by FePt Alloy Nanoparticles
and
Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, California 95064, and Department of Chemistry, Brown University, Providence, Rhode Island 02912
Received: November 19, 2007
In Final Form: January 2, 2008
Abstract:
FexPt100-x nanoparticles of different compositions (x = 63, 58, 54, 42, 15, and 0) were prepared and loaded
onto a glassy carbon (GC) electrode where their catalytic activities in the electroreduction of oxygen were
examined and compared. Cyclic and rotating disk voltammetric studies of the resulting FexPt100-x/GC electrodes
showed that the catalytic activity for oxygen reduction exhibited a peak-shape dependence on the particle
composition (x). Among the series of nanocatalysts under study, Fe42Pt58 particles showed the maximum
activity for O2 reduction in terms of the reduction overpotential and current density. This was accounted for
by the effects of the Fe content on the electronic structures of the Pt active sites and the resulting Pt-O
interactions. Kinetic analyses showed that direct four-electron reduction of adsorbed oxygen occurred on
these catalyst surfaces. Additionally, the rate constant of O2 reduction increased with increasing Pt content in
the alloy particles; yet, at x 
42, the rate constant exhibited only a very small increment. These studies
suggest that the Fe42Pt58 particles might represent an optimal composition for oxygen reduction among the
series of nanoparticle catalysts under the present study.
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