Competitive Adsorption and Interplay between Methanol and Water During Electro-Oxidation on Pd-Based Electrocatalyst

Abstract

The methanol oxidation reaction on palladium-based materials at different concentrations is studied theoretically and experimentally through its electrochemical response. Using a well-established reaction mechanism for the methanol oxidation reaction under alkaline conditions, we analyze the role of methanol, water adsorption and oxidation steps on the total electrochemical current obtained from linear voltammetry experiments. Solving the kinetic equations numerically, we fit the data obtained from experiments performed with a commercial catalyst at different methanol concentrations. Comparison of the numerical calculations with analytical expressions deduced following Laviron’s theoretical approach leads to discerning the adsorption contributions from methanol and water to the overall shape of the oxidation current from the nonlinear contribution associated with carbon-dioxide production. This identification allows, in turn, to use the peak current of the adsorption-related processes as a tool to characterize the overall catalyst’s performance.