Surface Structures of Rutile TiO₂ (011)

Abstract

Surface structures of rutile TiO(2) (011) are determined by a combination of noncontact atomic force microscopy (NC-AFM), scanning tunneling microscopy (STM), and density functional calculations. The surface exhibits rowlike (n x 1) structures running along the [01] direction. Microfaceting missing-row structural models can explain the experimental results very well. Calculated images for NC-AFM and STM are in good agreement with the experimental results. A decrease of the density of dangling bonds stabilizes the surface energy, which results in the microfaceting missing-row reconstructions.

The 2×1 reconstruction of the rutile TiO2(011) surface: A combined density functional theory, X-ray diffraction, and scanning tunneling microscopy study

“…The validity of the titanyl model was recently questioned by Kubo et al [18]. These authors reported that the titanyl structure is highly unstable and unlikely to occur (details of calculations were not provided), and, as an alternative, proposed a 'microfaceting' model where the removal of a pair of apex Ti 5c -O 2c gives rise to a 2 Â 1 surface periodicity.…”

“…In one report, the photo-induced oxidative and reductive half-reactions were observed to take place predominantly on the (0 1 1) and (1 1 0) surfaces of well-faceted TiO 2 microcrystals, respectively [11]. The need to understand such phenomena and the dearth of information on rutile (0 1 1) as compared to other TiO 2 surfaces has recently stimulated several surface science studies on single crystal TiO 2 (0 1 1) [13][14][15][16][17][18].…”

“…Also, its validity has recently been challenged by Kubo et al [18], who instead proposed a 'microfaceting' missing-row-type structure (Fig. 2a).…”

Model Studies on CO Oxidation Catalyst Systems: Titania and Gold Nanoparticles

“…First-principles calculations (T = 0 K) of the energetics and structure of stoichiometric TiO 2 surfaces were communicated by Ramamoorthy et al [59] and revealed that the (011) surface should be more corrugated than the (110) surface and dominated by five-fold coordinated Ti atoms. A combined (non-contact) atomic-force microscopy (AFM) and STM study including DFT calculations by Kubo et al [78] led to a similar interpretation of the (2 1) reconstructed (011) surface with some minor differences. The authors suggested a micro-faceting missing-row reconstruction.…”

Geometric structure of (011)(21) surface by low energy electron diffraction (LEED)

“…A scanning tunneling microscopy (STM) and density functional theory (DFT) investigation of TiO 2 (0 1 1)(2 Â 1) has suggested a surface terminated by titanyl (Ti@O) groups, possibly a cause of the enhanced photo-catalytic activity [4]. Another similar study suggested a microfaceting missing-row model [5]. More recent surface X-ray diffraction (SXRD) studies, however, have yielded data inconsistent with these two models and instead favored qualitively similar structures terminated by zigzag rows of twofold coordinated oxygen atoms asymmetrically bonded to fivefold titanium atoms [6,7].…”