Is carbon-supported Pt-WO_x composite a CO-tolerant material?

Frédéric Maillard (1) , Eric Peyrelade (1) , Yvonne Soldo-Olivier (1) , Marian Chatenet (1) , Eric Chaînet (1) , René Faure (1)

1 LEPMI - Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces

Pt-WO_x/C composite materials elaborated via a two-step impregnation/electrochemical reduction method have been characterized and tested for the electrooxidation of CO/H₂ mixtures. TEM and EDS measurements revealed that WO_x covered imperfectly the C particles. Nanometer-sized or agglomerated Pt particles were found on the WO_x/C surface. XRD measurements revealed the absence of diffraction peaks characteristic of crystalline WO_x and could indicate that this material is amorphous. No evidence of alloying between the Pt and W was observed. A significant improvement toward the electrooxidation of a CO_ads monolayer was observed for the composite material compared to pure Pt/C electrocatalyst, which is evidenced by a new electrooxidation peak at 0.55 V versus RHE (v=0.02 V s⁻¹). As the electrical charge below this electrooxidation peak is sweep rate dependant, it is probably associated to the electrooxidation of CO_ads on Pt sites at the interface with the WO_x/C support. The performance of the Pt-WO_x/C material for the electrooxidation of CO/H₂ mixtures was tested by polarization curves under steady-state conditions (0.001 V s⁻¹) or potentiostatic measurements under fuel cell relevant conditions and compared with that of commercial 20 wt% Pt/C and Pt-Ru/C materials.

Mots clés: Fuel cell electrocatalysts; Carbon-supported platinum nanoparticles; Tungsten oxides; Hydrogen electrooxidation; CO-tolerance

Domaines: Matériaux

Frédéric Maillard, Eric Peyrelade, Yvonne Soldo-Olivier, Marian Chatenet, Eric Chaînet, et al.. Is carbon-supported Pt-WO_x composite a CO-tolerant material?. Electrochimica Acta, 2007, 52 (5), pp. 1958-1967. ⟨10.1016/j.electacta.2006.08.024⟩. ⟨hal-00333728⟩