THEORETICAL-STUDY OF PHASE-TRANSITIONS AND UNDERPOTENTIAL DEPOSITION ON A LIQUID-VERTICAL-BAR-SOLID INTERFACE

The underpotential deposition of metals on a single crystal electrode in the presence of anions has been studied in the framework of a trian gular lattice gas model with pair-and three-particle lateral interacti ons. Interactions between the adsorbed species cause the formation of the ordered (root 3 X root 3) structures in accordance with the symmet ry of the lattice of adsorption sites. Using the mathematical equivale nce between the lattice gas model and Ising and Blume-Emery-Griffiths spin models, we apply the method of the real space renormalization gro up for investigation the phase diagram of the system and the processes of deposition and desorption of the ions. It is shown that the phase transitions, occurring in the system, influence the underpotential dep osition of metal ions strongly and are observed as sharp peaks in the voltammograms. We calculate coulometric and voltammetric curves and es timate the order of the lateral interaction magnitude between the adso rbed ions. (C) 1997 Elsevier Science S.A.