Interfacial properties of polycrystalline gold electrode in tetramethylammonium hydroxide solutions

Abstract

Electrochemical properties of polycrystalline gold electrode/tetramethylammonium hydroxide solution interface have been studied as function of concentration and temperature by cycling voltammetry and impedance spectroscopy. Interfacial impedance has constant phase element (CPE) character with parameters depending on potential and concentration. In wide concentration range, from 0.005 to 4 mol dm −3, (the highest concentration corresponds to stoichiornetric clathrate hydrate, (CH 3) 4NOH 10H 2O) CPE is identical with double layer capacity for potentials more negative than −0.28 V versus SCE up to hydrogen evolution. In this potential range the electrode is ideally polarizable and the determination of double layer capacity and charge density is possible. At far negative potentials double layer capacity depends on kind of cation and is independent of its concentration. In wide concentration and potential range strong adsorption of hydroxyl anions is observed on polycrystalline gold electrode. It is also shown that in (CH 3) 4NOH 10H 2O electrochemical measurements can be done in wide temperature range, including liquid and solid state of electrolyte.