Energetic and entropic contributions to the underpotential/overpotential deposition shifts on single crystal surfaces from lattice dynamics

Abstract: Electrochemical deposition of a metal on a foreign substrate may occur before or after the Nernst reversible potential, depending on the chemical nature of the substrate and adsorbate in question. Statistical mechanical treatment and a proper description of interactions between the particles of the system are necessary for an adequate theoretical representation of the electrochemical systems. In the present work, changes in relevant thermodynamic properties due to adsorption of a metal on a foreign single crystal (h k l) metallic surface are studied for a number of systems of electrochemical interest by means of quasi-harmonic (QH) lattice dynamics calculations with embedded atom method potentials at 300K. The metal couples considered involve silver, gold, platinum, palladium and copper. Underpotential and overpotential deposition trends observed for this set of transition metal systems are analyzed taking into account the changes in the internal energies and the entropic contributions due to deposition processes. The possibility of obtaining entropic information from measurements at different temperatures is also discussed. [Copyright &y& Elsevier]