Quantum chemical modeling study of adsorption of benzoic acid on anatase TiO2 nanoparticles.

The semi-empirical MSINDO method has been used to investigate the mode of adsorption of benzoic acid on the nano anatase TiO(2) (100) surface. The (100) surface is modeled with a Ti(36)O(90)H(36) cluster. Molecular dynamics simulations for the adsorption behavior of benzoic acid indicate it is linked to the TiO(2) surface through interactions from the oxygen atoms of the carboxylic acid moiety with surface titanium atoms. The benzoic acid may be positioned with its aromatic ring either parallel or perpendicular relative to the surface, however the perpendicular adsorption mode is more stable. The calculated substrate-surface interaction energy is influenced by the number of linkages between the substrate and the surface as well as the degree of hydrogen bonding between the acid hydrogen and lattice oxygen atom. The greater stability of the perpendicular adsorption orientation is ascribed to the higher number of linkages between the substrate and the surface. It is concluded that the simplified model is sufficiently detailed to elucidate surface interactions.