Author(s): Nguyen Duy Ket*, Tran Van Chung, Vu Minh Thanh, Ninh Duc Ha and Le Quang Tuan
A study on the electro-reduction of gold cyanide complex ions Au(CN)- 2 in acidic solution was presented in detail in this paper. Analyzing capacity of electrical double layer at the different polarized potentials let’s predict more precisely that the adsorbed product on electrode surface was reduced. Using the methods such as electrochemical impedance spectroscopy (EIS), potential linear scanning (LS,) has indicated that the gold cyanide complex ions Au(CN)- 2 were discharged at cathodic electrode through some steps. Indeed the obtained results showed that the gold cyanide complex ions Au(CN)- 2 were discharged at the electrode through three steps accompanying the CNion adsorption on cathode surface and that steps were controlled by the charge transfer rate. The presence of formic acid or trace amounts of Pb2+ (ppm) in the working solution might reduce cathodic polarised potencials so results in the improvement for the electroreduction process leading the increased plating rate, giving more uniform and brilliant plating layers.