Determination of lateral interaction parameters for copper monolayers deposited on polycrystalline platinum

Abstract

Experimental results, calculations and modelling involving voltammetric experiments of Cu deposition on polycrystalline Pt in acid medium are presented. The total lattice interaction energies have been studied by two different approaches. The lateral interaction parameter g from the Frumkin isotherm was calculated following a literature model that relates it to the peak half-width. A full Cu monolayer was deposited at 0.05 V for 250 s and then redissolved by an anodic scan. The calculated g values were related to the interactions between copper ad-atoms and hydrogen atoms at low Cu coverages and between copper ad-atoms themselves at high coverages. The long-range lattice interaction energies were estimated using an occupancy model developed for each crystallographic face of the polycrystalline Pt surface. The number and distances of Cu ad-atoms neighbouring a central one determines the total lattice interaction energy. For comparison, it was possible to demonstrate that each voltammetric peak has its own lattice interaction energy value, associated with the peak potentials. Thus, with the two parameters calculated here it was possible to describe the peak potentials and shapes for copper underpotential deposition on polycrystalline Pt surfaces.