Interfacial properties of polycrystalline gold electrodes in tetraalkylammonium electrolytes

Electrochemical properties of polycrystalline gold electrode in aqueous tet raalkylammonnium electrolyte solutions have been studied using cyclic volta mmetry and impedance spectroscopy. Results obtained indicate that adsorptio n on the gold electrode depends on the number of carbon atoms in tetraalkyl ammonium cation. Tetramethylammonium cation is not adsorbed on gold, contra ry to mercury and bismuth. Tetraethyl- and tetrapropylammonium cations are slightly adsorbed and tetrabutylammonium cation is strongly adsorbed with t he possibility of formation of condensed layers at the electrode surface. H owever they are desorbed from the electrode surface by potassium cations, w hich are considered as not specifically adsorbed on the gold electrode. It was suggested that tetrabuthylammonium cations do not interact with the met al surface, but they are pushed out from the solution. The dependence of th e double layer properties of tatraalkylammonium cations on the electrode ma terial confirmed this suggestion. In the case of tetramethyl- and tetraethy lammonium cations double layer capacity strongly depends on the metal but i n the case of the strongest adsorbed tetrabutylammonium cations, capacity i s metal independent. The dependence of anion follows the pattern observed p reviously on mercury electrode. Potential region in which the capacity is d etermined by the tetraalkylammonium cations becomes narrower with the incre asing absorbability of anions. Capacity at far negative potentials increase s with decreasing cation size and electrode I electrolyte interface can be described as a condenser filled with electrolyte. (C) 2001 Elsevier Science Ltd. All rights reserved.