ECTDMS CHARACTERIZATION OF CO ADSORBATE ON PLATINUM IN SULFURIC-ACID-SOLUTION

Carbon monoxide is of special interest because of its poisoning effect on platinum catalysts in fuel cells. By changing the electrolyte in a flow cell procedure, CO adlayers on platinum, electrochemically prefe rably oriented to (100) surfaces, were formed by adsorbing CO from sat urated 0.1 N H2SO4 solution at different adsorption potentials (100 - 900 mV/RHE). The UHV-surviving adsorbed layer was analyzed by means of Electrochemical Thermal Desorption Mass Spectrometry (ECTDMS) techniq ue. Beside CO, in the ''hydrogen'' region the water content is higher than in the ''double layer'' region. The adsorption isotherm of sulfat e ions and its effect on the anodic oxidation of CO is discussed.