Clarification of the interaction between Au atoms and the anatase TiO2 (112) surface using density functional theory

• Published in: Surface science 2018-04, Vol.670, p.23-32
• Main Authors: Tada, Kohei, Koga, Hiroaki, Okumura, Mitsutaka, Tanaka, Shingo
• Format: Article
• Language: English
• Subjects: Anatase TiO2; Au catalyst; DFT calculation; Metal/surface interaction
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2017.12.007

•The 1st atomic layer stability of anatase TiO2 (1 1 2) slab models was investigated by DFT.•Au atoms are adsorbed onto groove sites in the anatase TiO2 (1 1 2) strongly.•The stability of Au adsorption depends on the promotion of Au 5d electrons to the 6s and 6p orbitals.•Charge transfer does not affect the stability of Au atom adsorption onto the stoichiometric TiO2 surface.•Au atoms on the (1 1 2) surface are more stable than those on the (1 0 1) surface. A model (112) surface slab of anatase TiO2 (112) was optimized, and the adsorption of Au atoms onto the (112) surface was investigated by first-principles calculations based on DFT (density functional theory) with the generalized gradient approximation (GGA). Furthermore, the results were compared with those of Au/anatase TiO2 (101) system. The (112) surface has a ridge and a groove (zig-zag structure). The Au atoms were strongly adsorbed in the grooves but became unstable as they climbed toward the ridges, and the promotion of electrons in the 5d orbitals to the 6s and 6p orbitals in the absorbed Au atom occurred. At the Au/anatase TiO2 interface, the Au–Ti4+ coordinate bond in the (112) system is stronger than that in the (101) system because the promotion of electrons is greater in the former interaction than the latter. The results suggest that Au/anatase TiO2 catalysts with a higher dispersion of Au nanoparticles could be prepared when the (112) surface is preferentially exposed. [Display omitted]