KINETICS AND MECHANISM OF ADSORBED ETHYLENE ELECTROOXIDATION ON PLATINIZED PLATINUM UNDER POTENTIODYNAMIC CONDITIONS

The potentiodynamic electrooxidation of the adsorbed ethylene species on platinized platinum is studied at 40°, 60% and 80°C in IN H2SO4 saturated with ethylene at 1 atm pressure. The perturbation conditions are chosen to avoid the influence of ethylene readsorption. Experimental conditions to obtain the maximum coverage by the adsorbed species are established. The electrosorption process at the potential of maximum adsorption is related to a transient anodic current assigned to the electrooxidation of hydrogen adatoms. The kinetic parameters reveal that the electrochemical reaction is an activated process. Its interpretation and discussion are based on two possible schemes which are different than those earlier proposed for the ethylene electrooxidation under stationary conditions. The initial step in any of them is rate determining and corresponds either to the deprotonation of the adsorbed radical or to the water molecule discharge on the completely covered electrode surface. © 1979, The Electrochemical Society, Inc. All rights reserved.