Effect of potential on dissociative adsorption of water on titanium assessed by density functional theory calculations

Abstract

The present paper describes the atomistic modeling of the adsorption and dissociation of water molecules on the titanium Ti(0 0 0 1), Ti(101¯0) and Ti(11¯20) surface at different applied potentials in connection to recent studies of barrier film growth and dissolution on Ti. 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 different titanium surface planes 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(0 0 0 1), Ti(101¯0) and Ti(11¯20) surfaces 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 dependences of the free energy of the Ti/water systems on potential are obtained and discussed in terms of sequential dissociation of water to adsorbed hydroxyl and oxygen.