An in situ electrochemical quartz crystal microbalance study of polycrystalline gold electrodes in nitric acid solution

The dissolution and redeposition processes of Au in HNO3 solution at pH 1 and 0 were investigated as a function of sweep rate by in situ EQCM experiments. The results demonstrate that, at pH 1 and ν≤10 mV s−1, Au dissolves through a 3 e− oxidation at E>+1.0 V versus saturated calomel electrode (SCE), a process that, at ν≥10 mV s−1, is kinetically hindered with respect to upd of OH surface sublattices and subsequent 2-D-phase oxide formation. The inhibition arises from the presence of a close packed layer of nitrate oxyanions at the gold surface, although the layer is disrupted and the inhibition removed by the Au dissolution and reprecipitation processes that occur during potential cycling at low ν.