KINETICS OF CO2 ELECTROADSORPTION ON ELECTRODISPERSED PLATINUM-ELECTRODES IN ACID-SOLUTIONS

The kinetics of CO2 electroadsorption on electrodispersed Pt electrodes have been investigated in different acid electrolytes. The kinetic data obtained at different adsorption potentials, adsorption times and CO2 concentrations in solution have been interpreted in terms of two complex reaction mechanisms involving the formation of strongly and weakly bound reduced CO2 adsorbates through reactions involving s-H and w-H adatoms, respectively, and carbon dioxide. The reaction mechanism between H adatoms and CO2 implies the initial electroadsorption of H atoms, the transport of CO2 from the bulk of the solution to the reaction interface, and the formation of the reduced CO2 adsorbate. Under certain conditions, particularly when s-H adatoms are involved, the entire reaction approaches mass transport rate control. Conversely, the reaction between w-H adatoms and CO2 appears as a rather slow process. © 1990.