Effect of the structure of Pt–Ru/C particles on CO<sub>ad</sub> monolayer vibrational properties and electrooxidation kinetics - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Electrochimica Acta Année : 2007

Effect of the structure of Pt–Ru/C particles on COad monolayer vibrational properties and electrooxidation kinetics

Résumé

In this paper, we combined FTIR spectroscopy and COad stripping voltammetry to investigate COad adsorption and electrooxidation on Pt–Ru/C nanoparticles. The Pt:Ru elemental composition and the metal loading were determined by ICP-AES. The X-ray diffraction patterns of the Pt–Ru/C indicated formation of a Pt–Ru (fcc) alloy. HREM images revealed an increase in the fraction of agglomerated Pt–Ru/C particles with increasing the metal loading and showed that agglomerated Pt–Ru/C nanoparticles present structural defects such as twins or grain boundaries. In addition, isolated Pt–Ru/C nanoparticles have similar mean particle size (ca. 2.5 nm) and particle size distributions whatever the metal loading. Therefore, we could determine precisely the effect of particle agglomeration on the COad vibrational properties and electrooxidation kinetics. FTIR measurements revealed a main COad stretching band at ca. ν(COL) = 2030 cm-1, which we ascribed to a-top COad on Pt domains electronically modified by the presence of Ru. As the metal loading increased, the position of this band was blue shifted by ca. 5 cm−1 and a shoulder around 2005 cm−1 developed, which was ascribed to a-top COad on Ru domains. The reason for this was suggested to be the increasing size of Ru domains on agglomerated Pt–Ru/C particles, which lifts dipole–dipole coupling and allows two vibrational features to be observed (COad/Ru, COad/Pt). This is evidence that FTIR spectroscopy can be used to probe small chemical fluctuations of the Pt–Ru/C surface. Finally, we comment on the COad electrooxidation kinetics. We observed that COad was converted more easily into CO2 as the metal loading, i.e. the fraction of agglomerated Pt–Ru/C nanoparticles, increased.

Domaines

Matériaux

Dates et versions

hal-00386357 , version 1 (21-05-2009)

Identifiants

Citer

Frédéric Maillard, Antoine Bonnefont, Marian Chatenet, Laure Guétaz, Béatrice Doisneau-Cottignies, et al.. Effect of the structure of Pt–Ru/C particles on COad monolayer vibrational properties and electrooxidation kinetics. Electrochimica Acta, 2007, 53 (2), pp. 811-822. ⟨10.1016/j.electacta.2007.07.061⟩. ⟨hal-00386357⟩
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