Electrocatalytic oxidation of methanol to soluble products on polycrystalline platinum: Application of convolution potential sweep voltammetry in the estimation of kinetic parameters

Abstract

Irreversible oxidation of methanol on polycrystalline platinum leading to soluble products has been carried out by fast scan voltammetry, and the reaction has been studied under diffusion controlled process. The conventional analysis of current–potential data, viz. dependence of peak potential on scan rate and peak width measurements, resulted in the estimation of apparent diffusion coefficient of methanol and the anodic transfer coefficient of the electrode reaction. However, from the convolution potential sweep voltammetry, a more accurate and reliable kinetic data were obtained. Under the above conditions, methanol oxidation follows Butler–Volmer rate law with a linear variation of logarithmic heterogeneous rate constant with electrode potential. A constant apparent anodic transfer coefficient independent of electrode potential was observed pointing to the fact that the standard potential of the reaction cannot be determined from the voltammetric experiments. The experimental current–potential curve was compared with a theoretical voltammogram and further oxidation of products at the electrode surface has also been analyzed using limiting convolution current.