Valence band electronic structure characterization of the rutile TiO2 (110)-(1×2) reconstructed surface

Sánchez‐Sánchez, Carlos; Garnier, M. G.; Aebi, Philipp; Blanco-Rey, M.; Andrés, Pedro; Martín‐Gago, J. A.; López, María Francisca

doi:10.1016/j.susc.2012.09.019

Cited by 19 publications

(29 citation statements)

References 32 publications

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“…These results are in good agreement with a UPS study by Sánchez-Sánchez et al [16], which found that the Ti 3+ 3d derived gap state located at 1.2 eV BE is only present on the (1×2) reconstructed TiO 2 (110) surface.…”

Section: Cits On the Cross-linked (1×2) Reconstruction Of Rutile Tio supporting

confidence: 92%

“…The peak at -1.6 V was assigned to the (1×2) row and that at -1 V was assigned to defects in the band gap with the same origin as the peak found in UPS for lightly reduced TiO 2 (110). These two peaks presumably correspond to the minor and major peaks in the work of Sánchez-Sánchez et al [16].…”

Section: Introductionmentioning

confidence: 67%

“…An early photoemission spectroscopy study showed that the TiO 2 (110) surface with a (1×2) reconstruction exhibits a much more intense band-gap-state (BGS) peak than the TiO 2 (110)-(1×1) surface [15]. This was corroborated by an ultraviolet photoelectron spectroscopy (UPS) study by Sánchez-Sánchez et al [16], which shows that the BGS peak is composed of two individual components: a major peak located at a binding energy (BE) ~0.75 eV below the Fermi level (E F ) assigned to Ti 3+ species associated with the point defects in the TiO 2 bulk and a minor peak located ~1.2 eV below E F assigned to Ti 2 O 3 rows.…”

Section: Introductionmentioning

confidence: 86%

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Probing the local electronic structure of the cross-linked (1 × 2) reconstruction of rutile TiO2(110)

2016

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The electronic structure of cross-linked TiO 2 (110)-(1×2) has been investigated using scanning tunneling spectroscopy (STS) and by monitoring changes in ultraviolet photoelectron spectroscopy (UPS) following exposure of the surface to O 2 . STS reveals two states located in the bandgap, at 0.7 and 1.5 eV below the Fermi level. The population of these two states varies over different parts of the (1×2)reconstructed surface. An addition state at 1.1 eV above the Fermi level is observed at the double link part of the structure. All of the bandgap states are attenuated following exposure to O 2 , while the workfunction is increased. We attribute this to an electron transfer from the surface to the adsorbed oxygen.

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Section: Cits On the Cross-linked (1×2) Reconstruction Of Rutile Tio supporting

confidence: 92%

Section: Introductionmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 86%

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Probing the local electronic structure of the cross-linked (1 × 2) reconstruction of rutile TiO2(110)

2016

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“…Transition metal oxides have tremendous importance in a wide variety of technological applications such as heterogeneous catalysts, (photo-)electrodes, and gas sensors [1][2][3][4] . Among them, titanium dioxide (TiO 2 ) has also become the prototype material for surface science studies largely due to its ordered structure and capability of conduction upon reduction 2 .…”

Section: Introductionmentioning

confidence: 99%

CO Oxidation at Rutile TiO₂(110): Role of Oxygen Vacancies and Titanium Interstitials

Gong

2015

ACS Catal.

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We present a detailed investigation of the adsorption and oxidation of CO by O 2 at rutile TiO 2 (110). PBE, PBE+U, PBE+U-D methods were tested in calculations to allow a direct comparison of their accuracies. By utilizing PBE+U-D method, we found that the agreement between theoretical and experimental results has been improved. We then adopted PBE+U-D method on rutile TiO 2 (110) with different defects, i.e. Ti interstitials, O vacancies, or both. It is found that (i) CO adsorbs most favorably at the surface site that undergoes the most significant relaxation upon reduction by such defects; (ii) O 2 molecule adsorbs as O 2 -or O 2 2-besides the defects, and its dissociation is favorable only when two O 2-can occur by accepting the four excess electrons brought by a Ti interstitial; (iii) the catalytic cycle of CO oxidation by O adatoms from dissociated O 2 can be maintained with the help of Ti interstitials. These results are of importance to understand the role of different defects in metal oxide catalysts.

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“…Possible explanations for the different binding energies are that the oxygen vacancies are located at different lattice sites and/or forming clusters [33], or the existence of different types of defects [35,36].…”

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confidence: 99%

Engineering two-dimensional electron gases at the (001) and (101) surfaces ofTiO2anatase using light

et al. 2015

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We report the existence of metallic two dimensional electron gases (2DEGs) at the (001) and (101) surfaces of bulk-insulating TiO2 anatase due to local chemical doping by oxygen vacancies in the near-surface region. Using angle-resolved photoemission spectroscopy, we find that the electronic structure at both surfaces is composed of two occupied subbands of dxy orbital character. While the Fermi surface observed at the (001) termination is isotropic, the 2DEG at the (101) termination is anisotropic and shows a charge carrier density three times larger than at the (001) surface. Moreover, we demonstrate that intense UV synchrotron radiation can alter the electronic structure and stoichiometry of the surface up to the complete disappearance of the 2DEG. These results open a route for the nano-engineering of confined electronic states, the control of their metallic or insulating nature, and the tailoring of their microscopic symmetry, using UV illumination at different surfaces of anatase.In its pure stoichiometric form, the transition metal oxide (TMO) TiO 2 is a transparent insulator that crystallizes in mainly two different phases: rutile and anatase. Both phases have been studied extensively over the last decades, due to their photocatalytic properties discussed in several reviews [1][2][3][4]. Recently, a strong interest in the anatase phase of TiO 2 also surged, owing to its potential for applications in other research fields. For instance, networks of anatase nanoparticles are found in dye-sensitized solar cells [5,6], anatase thin films can be used as transparent conducting oxides [7], and devices based on anatase can be envisioned in spintronics [8,9]. To harness such a wide range of functionalities and guide potential applications using anatase, it is thus critical to understand its microscopic electronic structure, which will be ultimately responsible for the remarkable properties of this material. Moreover, as most applications in microelectronics or heterogeneous catalysis involve essentially the electronic states at the material's surface, it is crucial to directly measure and characterize such states.More generally, the study of two-dimensional electron gases (2DEGs) in TMO surfaces/interfaces has become a very active field of research. The archetypal example, SrTiO 3 -based heterostructures, display many fundamentally interesting properties [10][11][12], such as field-effect induced insulator-to-superconductor transitions [13], magnetism [14] and the coexistence of magnetism and superconductivity [15]. More recently, the discoveries of 2DEGs at the bare (001), (110) and (111) It is well established that the TiO atomic planes, and their ability to accommodate chemical doping by oxygen vacancies at the surface region, play a key role in the formation of the 2DEG at the surface of SrTiO 3 (001). Thus, as a step forward to understand the formation of 2DEGs in TMOs, it is natural to focus on pure TiO 2 crystals such as rutile or anatase. In fact, it is known that, for both rutile and anatase crystal sur...

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Valence band electronic structure characterization of the rutile TiO2 (110)-(1×2) reconstructed surface

Cited by 19 publications

References 32 publications

Probing the local electronic structure of the cross-linked (1 × 2) reconstruction of rutile TiO2(110)

Probing the local electronic structure of the cross-linked (1 × 2) reconstruction of rutile TiO2(110)

CO Oxidation at Rutile TiO₂(110): Role of Oxygen Vacancies and Titanium Interstitials

Engineering two-dimensional electron gases at the (001) and (101) surfaces ofTiO2anatase using light

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Valence band electronic structure characterization of the rutile TiO2 (110)-(1×2) reconstructed surface

Cited by 19 publications

References 32 publications

Probing the local electronic structure of the cross-linked (1 × 2) reconstruction of rutile TiO2(110)

Probing the local electronic structure of the cross-linked (1 × 2) reconstruction of rutile TiO2(110)

CO Oxidation at Rutile TiO2(110): Role of Oxygen Vacancies and Titanium Interstitials

Engineering two-dimensional electron gases at the (001) and (101) surfaces ofTiO2anatase using light

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CO Oxidation at Rutile TiO₂(110): Role of Oxygen Vacancies and Titanium Interstitials