Investigation on the interaction of butanol isomers and BaTiO3 (0 0 1) surface

The adsorption processes of four butanol isomers (n-butanol, tert-butanol, sec-butanol and isobutanol) on the BaTiO3 (0 0 1) surface were calculated based on the first-principles. From the geometrically optimized configuration, it is found that the adsorption occurs more easily when the H atom (Hm) in the O-H bond of the butanol molecules is close to the adsorption site on the BaTiO3 (0 0 1) surface. The adsorption process is characterized by the dissociation of Hm atom from the butanol molecules and the formation of covalent bonds with the O atom on the surface of BaTiO3. Among the four isomers, the sec-butanol has the largest adsorption energy of -1.422 eV, while the adsorption energy of the n-butanol is the smallest of -1.098 eV. Therefore, it is inferred that the adsorption process is chemisorption. Bader charge analysis indicates that the butanol isomer molecules act as electron acceptors to receive the charge from the BaTiO3 surface. In addition, the analysis on density of states shows that the C atom and H atom of butanol isomer molecules have obvious electronic orbital interaction with O atom on BaTiO3 surface. The charge transfer and O-H bond breaking and generation during the adsorption process are further confirmed by the charge density difference and electron localization function.