An electrocatalyst for methanol oxidation based on tungsten trioxide microspheres and platinum

Tungsten trioxide microspheres of 2–4 μm diameter have been prepared by controlled oxidation of tungsten carbide microspheres. These microspheres are characterized by XRD, SEM, and HRTEM. The microspheres are made of WO3 nanoparticles with an average diameter of around 15 nm. Platinum supported on these WO3 microspheres exhibits higher and stable electrocatalytic activity for methanol oxidation by a factor of around two, than commercial 20 wt.% Pt–Ru/Vulcan-XC72 carbon and 20 wt.% Pt–Ru/carbon microspheres even without Ru. The higher activity is attributed to the better tolerance to carbon monoxide of the Pt/WO3 catalyst. These Pt/WO3 microspheres appear to be a promising alternative anode material for direct methanol fuel cells. They replace Ru entirely and save a substantial amount of Pt in the Pt–Ru electrode that is presently employed in fluel cells.