ELECTROCHEMICAL OXIDATION OF METHANOL AT CHEMICALLY PREPARED PLATINUM-RUTHENIUM ALLOY ELECTRODES

Chemically prepared Pt-Ru alloy catalysts were investigated to study the effects of temperature, Pt loading, and heat-treatment on the kinetics of methanol oxidation in acid electrolyte. The maximum current density obtained for the Pt-Ru catalyst, dispersed on Vulcan XC-72R carbon, was about 600 mA/cm2 at 60-degrees-C and a Pt loading of 2.05 mg/cm2. The maximum catalytic shift due to the Ru modification of Pt was 200 mV at a current density of 160 mA/cm2. The activation energy for methanol oxidation is similar for both Pt and Pt-Ru. The Ru composition of the electrode stabilized at higher levels when the electrode was heat-treated. The oxidation current per mg of Pt decreased with an increase in the Pt loading. A phenomenological analysis of the catalytic shift for methanol oxidation at Pt-Ru electrodes favored the bifunctional catalyst model over models based on geometric and electronic factors.