Electrochemical dissolution of gold in acidic medium

Polycrystalline gold dissolves at high potentials in acidic medium even without the presence of complexing agents. In the present work the dissolution of gold is quantitatively studied by an inductively coupled plasma mass spectrometer (ICP-MS) directly connected to an electrochemical scanning flow cell (SFC). It is shown that the onset of gold dissolution coincides with the onset of the formation of 2D surface oxide (ca. + 1.3 V-RHE). An increase in the upper potential limit (UPL) during potential cycling or an increase in the holding potential during potential steps leads to an enhancement in the amount of dissolved gold. Moreover, a change in the dominating mechanism for gold dissolution with increasing potential is found in transient experiments. At lower potentials, gold is dissolved mostly during the gold oxide reduction, while at higher potentials anodic dissolution is the dominating process. Finally, the possible application of gold for stabilization of PtAu-based fuel cell catalysts is discussed. (C) 2012 Elsevier B.V. All rights reserved.