Effect of the TiO2 content as support with carbon toward methanol electro-oxidation in alkaline media using platinum nanoparticles as electrocatalysts

Abstract

Platinum nanoparticles supported on physical mixtures of Vulcan carbon and TiO2 (Pt/(C + TiO2)) were prepared by the borohydride method and tested for methanol electro-oxidation in alkaline media. X-ray diffraction (XRD) analyses showed peaks characteristic of Pt face-centered cubic (fcc) structure and peaks associated with TiO2 and carbon. Transmission electron microscopy (TEM) images showed the Pt nanoparticles distributed preferentially over the TiO2 support with average particle sizes between 5 and 6 nm. Cyclic voltammograms showed a decrease of Pt surface area with increasing TiO2 load while linear sweep in the presence of methanol showed Pt/(C + TiO2) (60:40) with the highest current density in accordance with chronoamperometry. The results were attributed to Pt-based nanoparticles on TiO2 which show enhanced catalytic activities for methanol oxidation due to a metal-support interaction. Furthermore, TiO2 is a semiconductor with low conductivity when compared to carbon. Thus, it is expected that an intermediate proportion of carbon and TiO2 as substrate could improve the activity of Pt nanoparticles without substantial loss of conductivity, resulting in a synergic effect.