Sputtered Pt-Ru Alloys as Catalysts for Highly Concentrated Methanol Oxidation

For possible catalytic anodes in direct methanol fuel cells (DMFCs) employing a 1:1 stoichiometric methanol-water reforming mixture, we have studied sputtered Pt-Ru catalysts over a wide composition range. The surface morphology of the catalyst films, determined from scanning electron microscopy studies, is rough and nanoporous and is dependent on the composition. The structure of the films has been verified as polycrystalline by X-ray diffraction analysis, which further shows that the cosputtered films are highly alloyed. The electrochemical behavior of the sputtered films has been evaluated for methanol oxidation using cyclic voltammetry and chronoamperometry in the H(2)SO(4)/CH(3)OH electrolyte at room temperature. The results indicate that Pt(0.53)Ru(0.47) is the optimal alloy composition for highly concentrated 16.6 M CH(3)OH, which corresponds to the stoichiometric fuel that will be used in next-generation DMFCs designed to mitigate methanol crossover. Long-time chronoamperometry measurements show that sputtered Pt-Ru catalysts maintain a stable performance after the initial decay.