Mathematical model of electrocatalysis of methanol oxidation at the mixture of nanocrystals of platinum and ruthenium dioxide

Abstract

Mathematical model representing a catalytic effect of a nanocrystal mixture of metallic platinum and ruthenium dioxide for electrooxidation of methanol is established. Dependance of a current density of the methanol electrooxidation on the chemical composition and size of nanocrystals is determined in the model. A good agreement between theoretical values and experimental results corroborates that electrooxidation of methanol is guided by a bifunctional mechanism. The model is based on the fact that the catalytic effect is proportional to the length of the contact border between nanocrystals of metallic platinum and nanocrystals of ruthenium dioxide. Ru-OH particles are formed on the Ru atoms at the border of crystal grains, at potentials more negative than on platinum. These species oxidize firmly bound intermediates COad located on the adjacent Pt atoms and thus release the Pt atoms for adsorption and dehydrogenation of subsequent molecules of methanol.