The kinetics of methanol electro‐oxidation on well‐characterized Pt‐Ru alloy surfaces were measured in sulfuric acid solution as a function of temperature. The alloy surfaces were prepared in ultrahigh vacuum with the surface composition determined by low energy ion scattering. It was found that the activity of Ru towards the dissociative adsorption of methanol is a strong function of temperature. This change in the adsorptive nature of the Ru sites with temperature produced a variation in the optimum surface composition with temperature. The optimum surface had an Ru content which increased with increasing temperature, from close to ≈10 atomic percent (a/o) Ru at 25°C to a value in the vicinity of ≈30 a/o at 60°C. The shift in optimum composition with temperature was attributed to a shift in the rate‐determining step from methanol adsorption/dehydrogenation at low temperature to the surface reaction between the dehydrogenated intermediate and surface oxygen at high temperature. The apparent activation energies were consistent with this change in the rate‐determining step.
BT - Journal of The Electrochemical Society DO - 10.1149/1.2055007 IS - 7 N2 -The kinetics of methanol electro‐oxidation on well‐characterized Pt‐Ru alloy surfaces were measured in sulfuric acid solution as a function of temperature. The alloy surfaces were prepared in ultrahigh vacuum with the surface composition determined by low energy ion scattering. It was found that the activity of Ru towards the dissociative adsorption of methanol is a strong function of temperature. This change in the adsorptive nature of the Ru sites with temperature produced a variation in the optimum surface composition with temperature. The optimum surface had an Ru content which increased with increasing temperature, from close to ≈10 atomic percent (a/o) Ru at 25°C to a value in the vicinity of ≈30 a/o at 60°C. The shift in optimum composition with temperature was attributed to a shift in the rate‐determining step from methanol adsorption/dehydrogenation at low temperature to the surface reaction between the dehydrogenated intermediate and surface oxygen at high temperature. The apparent activation energies were consistent with this change in the rate‐determining step.
PY - 1994 SP - 1795 EP - 1803 ST - J. Electrochem. Soc. T2 - Journal of The Electrochemical Society TI - Temperature-Dependent Methanol Electro-Oxidation on Well-Characterized Pt-Ru Alloys VL - 141 SN - 00134651 ER -