Methanol oxidation on polycrystalline Pt and Pt + Ru alloy electrodes

Abstract

The electrooxidation of methanol in acid was studied on polycrystalline Pt and a Pt-Ru 160-401 alloy by arc-melting. The technique used was an alternative type of pulse voltamrnetry where voltammograms were constructed by chronoamperometric data collected alter the application of a potential program on the electrode. The former was chosen such that before each set of measurements the electrode surface was activated and cleaned from the resulting methanolic poison. It was found that on a surface free of poisornous speries dissociative chemisorption involving all electron transfer is the rds over a wide potential region. Also, on a poison-free surface. Pt and Pt-Ru show similar catalytic avtivities at low polarisations whereas Pt-Ru is a better catalyst at high over potentials. In situations where contamination is expected to occur (higher concentrations. longer times) Pt-Ru is always a superior catalyst due to the oxidative removal of the adsorbed poison by surface Ru oxides.