Effect of cation adsorption on the kinetics of anion electroreduction Part II. Effect of the adsorption of organic cations in small concentrations on the kinetics of anion electroreduction

The phenomenon of the decrease of the accelerating action of small amounts of tetraalkylammonium cations on the electroreduction of anions, when the negative charge on the mercury electrode increases and when the supporting electrolyte concentration increases, is investigated. It is explained by the redistribution of the surface excesses of organic and inorganic cations in the electric double layer within the framework of the slow-discharge theory and the improved Stern-Grahame model considering forcing of organic ions out of the electric double layer with the increasing negative charge of the electrode surface. The psi(1) potential in the presence of adsorption of the surface-active organic cations is calculated and the corrected Tafel plots are constructed for solutions of different composition. (C) 1999 Elsevier Science S.A. All rights reserved.