Electrochemical 3D metal phase formation on UPD modified foreign substrates

The electrochemical 3D metal (Me) phase formation on a foreign substrate (S ) takes place in the supersaturation or overpotential deposition (OPD) rang e. In systems with strong vertical Me-S binding energy, low-dimensional Me phases can already be formed in the undersaturation or underpotential depos ition (UPD) range. In both cases, surface inhomogeneities play an important role in thermodyna mics, structure and kinetics of Me phase formation processes. In the first part of this paper, theoretical aspects of electrochemical UPD and OPD Me p hase formation are discussed, whereas in the second part experimental resul ts from selected model systems are presented.