Radioactive Labeling Study and FTIR Measurements of Methanol Adsorption and Oxidation on Fuel Cell Catalysts

Abstract

AbstractThe adsorption and the electrooxidation of methanol‐derived surface CO on fuel‐cell grade platinum and platinum‐ruthenium alloy nanoparticle catalysts were studied using a combination of electrochemical measurements and radioactive labeling (thin foil radioactive labeling technique) and in situ infrared reflectance spectroscopy. The kinetics of formation of surface and bulk products coming from methanol and surface/bulk exchange processes were found to be significantly different on Pt compared to Pt/Ru. The observed difference in the kinetics of CO adsorption underlines the electronic effect in the surface catalytic activity due to modification of the electronic structure of surface platinum atoms by ruthenium. Correlation between FTIR and radiolabeling measurements indicated that the adsorption of CO from methanol is a very slow process at low potential but that the coverage by CO poison is greater at higher potential. Then, the results obtained from both analytical techniques (in situ IR reflectance spectroscopy and radioactive labeling method) displayed very good agreement and allowed us to validate them for the investigation of the methanol oxidation mechanism.