Oxidation of methanol on a platinum electrode in alkaline medium: Effect of metal ad-atoms on the electrocatalytic activity

A mechanistic investigation of the electrochemical oxidation of methanol was worked out in alkaline medium in order to interpret the effect of some foreign metal ad-atoms (Pb. Bi, Cd, Tl) on the electrocatalytic activity of platinum.The rate-determining step being a surface reaction between adsorbed hydroxyls and a methanol chemisorption intermediate, the positive effect met with Pb and Bi may be explained through the bifunctional theory of electrocatalysis, whereas the negative effect met with Cd and Tl may come from the inhibiting behaviour of these latter ad-atoms.