Gold twin-electrodes in thin-layer electrochemistry

The characteristics of a gold twin-electrode system in a thin-layer cell containing 0.1 M perchloric acid, and varying amounts of sodium chloride, were investigated by triangular sweep voltammetry. The “adsorbed oxygen” layer starts to form above 1 V, and the peak from reduction of this layer shifts from 0.88 V to 0.65 V on changing the turn-around potential from 1.02 to 2.0 V. A distinct adsorption peak appears at 0.5 V, with cathodic peaks at 0.4 V and -0.1 V. Chloride adsorption is observed at 0.6 V, with desorption at 0.4 V. The dissolution of the gold electrode to gold(III) chloride occurs at 1.1 V; but this reaction is blocked above 1.2 V by the formation of the “adsorbed oxygen” layer. The peak from the reduction of the gold(III) chloride is located at 0.7 V and is separable from the “adsorbed oxygen” reduction peak. The electrode surface obtained from the reduction of gold(III) chloride shows characteristics different from those obtained by the reduction of the “adsorbed oxygen” layer.