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

Pt-WOx/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 WOx covered imperfectly the C particles. Nanometer-sized or agglomerated Pt particles were found on the WOx/C surface. XRD measurements revealed the absence of diffraction peaks characteristic of crystalline WOx 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 COads monolayer was observed for the composite material compared to pure Pt/C electrocatalyst, which is evidenced by a new electrooxidation peak at 0.55V versus RHE (v=0.02Vs-1). As the electrical charge below this electrooxidation peak is sweep rate dependant, it is probably associated to the electrooxidation of COads on Pt sites at the interface with the WOx/C support. The performance of the Pt-WOx/C material for the electrooxidation of CO/H2 mixtures was tested by polarization curves under steady-state conditions (0.001Vs-1) or potentiostatic measurements under fuel cell relevant conditions and compared with that of commercial 20wt% Pt/C and Pt-Ru/C materials