Nanosized Pt and PtRu colloids as precursors for direct methanol fuel cell catalysts

Abstract

Nanosized Pt and PtRu colloids have been prepared by a microwave-assisted polyol process and transferred to a toluene solution of decanthiol. Vulcan XC-72 was then added to the toluene solution to adsorb the thiolated Pt and PtRu colloids. TEM examinations showed nearly spherical particles and narrow size distributions for both supported and unsupported metals, XPS characterization of the PtRu colloid revealed mostly Pt(0) and Ru(0), with some traces of Pt(IV) and Ru(IV). The carbon supported Pt and PtRu nanoparticles were activated by thermal treatment to remove the thiol stabilizing shell. The electrooxidation of liquid methanol on these catalysts was investigated at room temperature by linear sweep voltammetry and chronoamperometry. The results showed that the alloy catalyst was catalytically more active than pure platinum. The heat-treated catalyst was also expectedly more active than the non-heat-treated ones because of the successful removal of the organic shell which might interfere with reactant adsorption in the methanol oxidation reaction.