Phase Transitions in Electrochemical Adsorption

P. A. Rikvold and A. Wieckowski

In Thin Films and Phase Transitions on Surfaces; Proceedings of the Second East-West Surface Science Workshop, EWSSW96, Pamporovo, Bulgaria, February 18-24, 1996, edited by M. Michailov (Institute of Physical Chemistry, Bulgarian Academy of Sciences, Sofia, 1996), pp. 58-75.


A technique of statistical-mechanical lattice-gas modeling of chemisorption, applicable to electrochemical systems dominated by lateral interactions, is reviewed. A strategy for applying the method to specific systems is outlined. This includes microscopic model formulation, calculation of zero-temperature phase diagrams, numerical calculation of thermodynamical and structural quantities at nonzero temperatures, and estimation of the effective, lateral interaction energies. The general discussion is illustrated by applications to the following specific problems. The poisoning by sulfur of hydrogen adsorption on platinum (111), the electrochemical adsorption of organics on polycrystalline copper and nickel and of urea on single-crystal platinum (100), and the underpotential deposition of copper on single-crystal gold (111).