DFT modelling of ethanol on BaTiO3 (001) surface

The Density Functional Theory (DFT) within the Generalized Gradient Approximation (GGA) approach and van der Waals (vdW) corrections have been used to study the molecular adsorption of ethanol over the BaTiO3 (0 01) surface. Two kinds of surfaces have been considered: (i) a non-defective surface, and, to model a more realistic system, (ii) a surface with the presence of an oxygen vacancy (V-o). Chemisorption and physisorption has been found to occur. The O deficiency included at surface provokes the appearance of a small magnetic moment (- 0.48 mu(B)), and the presence of non-confined electrons, which leads to n-type electrical conductivity. In chemisorption, the oxygen of the molecule binds with 2 barium atoms at the surface, while a hydrogen atom is dissociated from the molecule to bind with an oxygen atom at the surface or to occupy the V-o region; attained adsorption energies fluctuate from -1.00 eV to - 2.26 eV (V-o surface). In physisorption, the oxygen of the molecule seems to bind with a barium at the surface, however, no impact over the structure and atomic charges of the molecule or surface has been perceived; obtained adsorption energies range from - 0.20 eV to - 0.50 eV (V-o surface). Computed adsorption energies for clean and V-o surfaces show that V-o sites are more suitable for molecular adsorption to occur.