Surface Diffusion and Dissolution Kinetics in the Electrolyte-Metal Interface

Modeling of dealloying has often used a local bond-breaking approach to define the energy barrier to simulate dissolution and surface diffusion. The energy barriers are tacitly assumed to be independent of the local solution chemistry at the metal/solution interface. In this work, an interaction energy parameter is added to the local bond-breaking model that accounts for the species-specific physics of the actual atom-water molecule, atom-ion interactions and allows complex atomistic behavior to be abstracted in the modeling of the diffusion and dissolution processes. Variations in the interactions of the electrolyte components with the metal atoms led to the prediction of different surface morphologies on a binary alloy sample surface that mirror the behaviors experimentally observed in dealloying experiments in Au-Cu alloys including the formation of Au-enriched surface islands at applied potentials below the critical potential and three-dimensional porosity at applied potentials above the critical potential. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3478572] All rights reserved.