An in situ scanning tunneling microscopy study of Ag electrodeposition on Au(111)

In situ scanning tunneling microscopy (STM) was used to study the electrode position of silver on Au(111) electrodes from sulfuric acid solution. The p rocess was followed in both the underpotential and overpotential regions. S TM images of underpotentially deposited silver revealed a series of ordered adlayer structures of increasing coverage with decreasing potential, namel y (root 3x root 3)R30 degrees, a distorted hexagonal stripe pattern, a (3x3 ) and, finally, a close-packed (1x1) layer. The bulk deposition was also mo nitored as a function of the electrode potential. At low overpotentials, a layer-by-layer growth up to at least 10 monolayers was detected. Additional ly, a 3D cluster growth took place at the step edges. Finally, deposition o f a thick silver layer resulted in the leveling of substrate defects and a very flat surface was obtained.