Particle size and alloying effects of Pt-based alloy catalysts for fuel cell applications

Citation
Mk. Min et al., Particle size and alloying effects of Pt-based alloy catalysts for fuel cell applications, ELECTR ACT, 45(25-26), 2000, pp. 4211-4217
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
ELECTROCHIMICA ACTA
ISSN journal
0013-4686 → ACNP
Volume
45
Issue
25-26
Year of publication
2000
Pages
4211 - 4217
Database
ISI
SICI code
0013-4686(2000)45:25-26<4211:PSAAEO>2.0.ZU;2-#
Abstract
Carbon-supported Pt-based binary alloy electrocalalysts (Pt-Co, Pt-Cr and P t-Ni) were prepared by incipient wetness method to investigate the origin o f the enhanced activity of the oxygen reduction reaction in fuel cells. The composition of these catalysts was adjusted to 3:1 (Pt:M, atomic%, M = Co, Cr and Ni). Prepared catalysts were characterized by various physical and electrochemical techniques, that is, energy dispersive X-ray spectrometry ( EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ra y absorption spectroscopy (XAS) and cyclic voltammetry (CV). XRD analysis s howed that all prepared catalysts exhibited face-centered cubic structures and had smaller lattice parameters than Pt-alone catalyst. Pt-alone and Pt- based alloy catalysts showed increasing specific activities with decreasing surface area. This indicates that oxygen reduction on platinum surface is a structure-sensitive reaction. According to CV and X-ray absorption near-e dge structure (XANES) results, the structure-sensitivity of Pt and Pt-based alloy catalysts for oxygen reduction seems associated with the adsorption strength of oxygen intermediates on the Pt surface. In addition, the Pt-bas ed alloy catalysts showed significantly higher specific activities than Pt- alone catalysts with the same surface area. This phenomenon comes from the seduced Pt-Pt neighboring distance as the catalysts were alloyed. The reduc ed Pt-Pt neighboring distance is favorable for the adsorption of oxygen. (C ) 2000 Elsevier Science Ltd. All rights reserved.