Effect of dissolved LiCl on the ionic liquid-Au(111) interface: an in situ STM study

The structure of the electrolyte/electrode interface plays a significant role in electrochemical processes. To date, most studies are focusing on understanding the interfacial structure in pure ionic liquids. In this paper in situ scanning tunnelling microscopy (STM) has been employed to elucidate the structure of the charged Au(111)-ionic liquid (1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate, [Py-1,Py-4]FAP) interface in the presence of 0.1 M LiCl. The addition of the Li salt to the ionic liquid has a strong influence on the interfacial structure. In the first STM scan in situ measurements reveal that Au(111) undergoes the (22 x root 3) 'herringbone' reconstruction in a certain potential regime, and there is strong evidence that the gold surface dissolves at negative electrode potentials in [Py-1,Py-4]FAP containing LiCl. Bulk deposition of Li is obtained at -2.9 V in the second STM scan.