Gold dissolution: towards understanding of noble metal corrosion

Abstract

The electrochemical dissolution of gold is an intricate topic and even though it has been studied for more than 50 years, its understanding remains rather limited. In the current work, we obtain unique information on gold dissolution by using a setup composed of a micro-electrochemical scanning flow cell (SFC) and inductively coupled plasma mass spectrometry (ICP-MS). Thus, comprehensive online gold dissolution profiles during the initial stage of oxidation as a function of the potential, time and pH are presented. A microscopic model explaining the experimental findings is proposed. According to this model, two dissolution mechanisms take place in two different potential regions: at low anodic potentials the dissolution is driven by the place-exchange between metal and adsorbed hydroxyl/oxygen ions, while at higher potentials the oxygen evolution reaction taking place on the surface of gold oxide initiates concomitant gold loss.