Multi-Scale Modeling of the Initial Stages of Anodic Oxidation of Titanium

Abstract

The present paper describes the nanoscale modeling of the adsorption and dissociation of water molecules on the titanium Ti (001) surface at different applied potentials and its connection to a previously proposed continuum scale approach to the growth and dissolution of thin barrier films on Ti in water-containing electrolytes. The theoretical study of titanium/water interactions is presented as combination of static and molecular dynamics calculations using density functional theory (DFT). The vibration frequencies of adsorbed H2O put emphasis on its interaction with the titanium surface and provide further information about the bond strength and the changes in the molecular structure. The adsorption and dissociation geometry of water molecules on Ti (001) surface in an electrochemical environment is investigated using the double reference method that allows assessing the elementary steps of water dissociation as depending on the applied potential. The dependence of the free energy of the Ti/water system on potential is obtained and discussed in terms of sequential dissociation of water to adsorbed hydroxyl and oxygen.