Rotating Rate Dependency of Methanol Oxidation on a Smooth Polycrystalline Platinum Surface

Abstract

Methanol adsorption and oxidation on platinum based catalysts have been extensively studied on well-characterized single crystal Pt, polycrystalline Pt, PtRu alloys, as well as high surface area catalysts. However, the quantitative kinetic and mechanistic studies using hydrodynamic techniques such as rotating disk electrode (RDE) or rotating ring-disk electrodes (RRDE) have been severely limited , , . The aim of this study was to examine the kinetics of methanol oxidation on a polycrystalline platinum rotating disc electrode in an acidic solution. The experiments were carried out in a conventional electrochemical cell. The electrolyte consisted of a solution of approximately 1M, de-oxygenated methanol and 0.5MH2SO4 at room temperature. The rotating disk electrode (RDE) measurements for the methanol oxidation on the Pt disk electrode were obtained at various rotation rates. Polarization curves obtained with the RDE measurements indicate that the kinetics and mechanism of the methanol oxidation are potential dependent. A mass transport corrected Tafel slope of 125 mV/decade was found on the relatively oxide free surface and is indicative of the first electron transfer as the rate determining step.