INFLUENCE OF POLARIZATION TIME AND TEMPERATURE ON THE ADSORPTION OF CARBON-DIOXIDE ON PLATINUM

Cyclic voltammetry measurements were performed at platinum electrodes in 0.5M H2SO4 saturated With CO2. Depending on the temperature and pre-polarization lime of the electrode, different oxidation potentials of the adsorbed CO2 species are observed which provide evidence that three different intermediates are formed. From literature data it can be concluded that the adsorption at higher temperatures and short pre-polarization times favor the formation of COOH(ad) (oxidation potential 520 mV/SCE) as adsorbed intermediate, while lower temperatures and longer pre-polarization times (e.g., 30 min) favor the formation of CO(ad) (oxidation potential at about 650 mV/SCE). Pre-polarization times of several hours lead to an oxidation peak at 280 mV/SCE which is assigned to the adsorption product HCOOH(ad).