In situ scanning tunneling microscopy of AU(111) in acidic potassium cyanide - Adsorption of cyanide and dissolution of gold

Linear sweep voltammetry and in-situ scanning tunneling microscopy (STM) have been used to examine Au(111) electrodes in 0.1 M HClO₄ containing 50 μM KCN. In situ STM imaging revealed that adsorption of cyanide species commenced predominantly at the hcp domains of the reconstructed Au(111), followed by a lateral growth to lift the reconstruction structure. A number of cyanide adlattices, including (6 × 6) on reconstructed Au(111) at 0.1 V (vs. SCE), and (√7 × √7)R19.1 and (√7 × √21)oblique structures on the unreconstructed Au(111) were found within the potential region of 0.2 and 0.3 V. The cyanide adlayer underwent further restructuring at 0.4 V, where dissolution of gold also commenced. Dynamic STM imaging permitted real-time monitoring of the etching event of the gold surface, where a pseudo layer-by-layer mechanism was observed.