NANOSCALE STUDIES OF AG ELECTRODEPOSITION OM HOPG(0001)

The electrodeposition of Ag on HOPG (0001) substrate is studied using conventional electrochemical methods (cyclic voltammetry, chronoampero metry) and in situ scanning tunnelling microscopy (STM). Due to a weak substrate-deposit interaction the deposition of kg occurs according t o a Volmer-Weber island growth mechanism. At relatively low overpotent ials the electrodeposition reaction is mainly initiated on steps and o ther surface defects. The initial deposition kinetics can be described by a model involving progressive nucleation on active sites and diffu sion-controlled 3-D growth. The analysis of experimental results shows that the 4-atomic Ag cluster represents the critical nucleus in the o verpotential interval -35mV < eta < -10mV. It is demonstrated that loc al nanoscale deposition of Ag on flat HOPG (0001) terraces can be indu ced using STM technique and specific pulse polarisation routines.