(Invited) Interpretation of Certain Features of the Interface Stress vs. Electrode Potential Curves of Gold with the Help of Dual Dynamic Voltammetry

It is a widespread opinion that the electrochemical behavior of gold in aqueous media has been thoroughly studied, and the interface stress changes of gold can be explained by monolayer oxide formation/removal and adsorption phenomena. However, in spite of the voluminous literature on this subject, an understanding of these systems and processes is far from complete. The combination of in-situ interface stress measurements and dual dynamic voltammetry brings new insights into the complexity of such systems. One remarkable result is that in the oxide reduction region of gold in sulfuric acid solutions a sudden change in the slope of the interface stress vs. electrode potential curve recorded during the negative-going scan of the cyclic voltammogram can be observed. By applying the dual dynamic voltammetric method to a gold/gold rotating ring-disk electrode (RRDE) it could be shown that the sharp change in the slope of the surface stress vs. potential curve recorded in the oxide reduction region of gold in sulfuric acid solutions is accompanied by the formation of soluble, electrochemically reducible gold species which can be detected at the ring electrode.