Electrochemical analysis of high temperature methanol electro-oxidation at Pt-decorated Ru catalysts

Methanol electro-oxidation at Pt-decorated unsupported Ru catalysts having a Pt loading of 0.1 mg cm2 has been investigated in situ in direct methanol fuel cells at high temperatures. The chemistry and morphology of the decorated catalyst has been studied by X-ray techniques and electron microscopy. An analysis of the stripping behaviour of adsorbed CO-like species has been carried out to obtain information on the electrocatalytic activity of the Pt-decorated Ru anode in relation to carbon supported Pt-Ru (1:1) alloy and bare unsupported Ru catalysts. The promoting effect of decorating Pt particles has been investigated by cyclic voltammetric analysis in the presence of a continuous methanol supply. The decorated catalyst has shown lower intrinsic catalytic activity with respect to the Pt-Ru alloy; yet, the decorating particles promote methanol dehydrogenation and adsorption of methanolic residues on the Ru support allowing the reaction to occur at significant rates even in the presence of small Pt amounts.