Electrochemical impedance spectroscopy of methanol electrooxidation on PtRu/C catalysts

The kinetic parameters of methanol electrooxidation on PtRu/C catalysts were investigated by electrochemistry impedance spectroscopy(EIS). The results from EIS at various potentials reveal that the cathodic polarization would contribute to enhancing methanol electrooxidation activity. The impedance behavior of methanol electrooxidation on PtRu/C catalysts at different potentials can be well explained by using the deduced kinetic theory involving one intermediate adsorbate. At low potentials, splitting of the first C-H bond of CH₃OH molecule with the first electron transfer is rate-determining step on various PtRu/C electrocatalysts, while at higher potentials, the oxidation reaction of CO ads gradually becomes rate-determining step. The change of intermediate CO_ad_s coverage and its effect on faradic current of methanol electrooxidation were also discussed according to experimental and theoretical results from EIS.