In situ Video-STM studies of sulfate dynamics on Au(1 1 1)

In situ video-rate scanning tunneling microscopy studies of the anion adlayer on Au(1 1 1) electrodes in sulfate-containing electrolytes are presented that provide direct data on the structure and dynamics of the potential-induced phase transition between the disordered adlayer and the ordered (√3 × √7) structure as well as of local transient structures in the disordered adsorbate phase. Specifically, strong correlations between adsorbates spaced at distances of √3 Au surface lattice constants along the [112¯] directions of the metal substrate are observed, supporting the formation of a 1D (bi)sulfate network via hydrogen-bonding along this direction. This network structure is in accordance with the rather slow adsorbate dynamics with residence times in the range of milliseconds or larger.