Photoinduced electron transfer from anatase to rutile in partially reduced TiO2 (P-25) nanoparticles: An ESR study

Komaguchi, Kenji; Nakano, Haruka; Araki, Atsunori; Harima, Yutaka

doi:10.1016/j.cplett.2006.07.003

Cited by 93 publications

(88 citation statements)

References 21 publications

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“…The E FB is usually obtained from Mott-Schottky plots from electrochemical impedance spectroscopy, as well as by some other electrochemical and spectro-electrochemical techniques [7][8][9]. The spectro/photo/ electrochemical measurements by Jankulovska et al [8] confirmed the positive offset of 0.2 eV between the CBMs of anatase and rutile, and other measurements, like EPR [10], photoluminescence [11], photocatalytic Ag + reduction [12,13] and H 2 evolution [14] on mixed-phase particles, also reported the CBM of anatase being higher than that of rutile. In contrast to these works, all photoelectron spectroscopy (PES) studies -carried out on layers in electrical contact and in a vacuum environment -seem to agree that the CBM of rutile is lying higher [15][16][17].…”

Section: Introductionmentioning

confidence: 92%

Water splitting and the band edge positions of TiO2

Deák

Kullgren

Aradi

et al. 2016

Electrochimica Acta

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Section: Introductionmentioning

confidence: 92%

Water splitting and the band edge positions of TiO2

Deák

Kullgren

Aradi

et al. 2016

Electrochimica Acta

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“…Strong interfacial regions between the phases have been suggested to facilitate charge transfer. [22][23][24] Other work attributes special four-coordinated Ti interfacial sites as contributing to the increased photo reactivity. 9,15,25,26 Band offsets at semiconductor heterojunctions are fundamental parameters which govern the transport properties of electrons, and the differences in energy of the bands determine the direction and magnitude of the electrical current.…”

Section: Introductionmentioning

confidence: 99%

The nature of interfaces and charge trapping sites in photocatalytic mixed-phase TiO2 from first principles modeling

García

Nolan

Deskins

2015

The Journal of Chemical Physics

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Mixed phase rutile/anatase catalysts show increased reactivity compared with the pure phases alone. However, the mechanism causing this effect is not fully understood. The electronic properties of the interface and the relative energy of the electron in each phase play a key role in lowering the rate of recombination of electron hole pairs. Using density functional theory and the +U correction, we calculated the bands offsets between the phases taking into account the effect of the interface. Our model included several thousands atoms, and thus is a good representation of an interface between actual nanoparticles. We found rutile to have both higher conduction and valence band offsets than rutile, leading to an accumulation of electrons in the anatase phase accompanied by hole accumulation in the rutile phase. We also probed the electronic structure of our heterostructure and found a gap state caused by electrons localized in undercoordinated Ti atoms which were present within the interfacial region. Interfaces between bulk materials and between exposed surfaces both showed electron trapping at undercoordinated sites. These undercoordinated (typically four) atoms present localized electrons that could enable reduction reactions in the interfacial region, and could explain the increased reactivity of mixed-phase TiO2 photocatalyst materials.

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“…Komaguchi et al [47] also show evidence for electron transfer from anatase to rutile due to the presence of trapping sites. Pure phase anatase and rutile as well as P25 catalysts were partially reduced and then subjected to light of wavelength less than the rutile BG.…”

Section: Rutile and Anatase Polymorphs Of Tiomentioning

confidence: 93%

“…From UV Raman spectra of the 700-750°C calcined catalysts, the authors confirm that both rutile and anatase coexist at the surface and therefore have surface phase junctions. It has been postulated by many authors [23,25,39,[46][47][48] that it is the presence of surface phase junctions in mixed phase TiO 2 that facilitates the electron transfer between the two phases upon photoexcitation and therefore improves charge separation, reduces recombination and subsequently increases photocatalytic activity.…”

Section: Rutile and Anatase Polymorphs Of Tiomentioning

confidence: 99%

Photoreaction of Au/TiO2 for hydrogen production from renewables: a review on the synergistic effect between anatase and rutile phases of TiO2

Connelly

Ahmed

Idriss

2012

Mater Renew Sustain Energy

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The review focus is on hydrogen production from renewables using photocatalysis. In particular we focus on the role of synergism on the reaction rate. Among the most studied examples for this phenomenon are catalysts based on TiO 2 . TiO 2 exists in two common phases: anatase and rutile, with the latter more thermodynamically stable. For hydrogen production the photocatalyst is often composed of nano-size precious metals deposited on TiO 2 (such as Pt, Pd, or Au). It has been observed by many researchers over a decade that M/TiO 2 rutile is far less active than M/TiO 2 anatase. Yet, the presence of the two phases together results in considerable enhancement of the reaction rate when compared to M/TiO 2 anatase alone. The main reason for this is the increase of the charge carriers' lifetime allowing for electron transfer to hydrogen ions and hole transfer to oxygen ions (and/or the sacrificial agent used). In this work we review the few proposed models, so far, explaining the way by which this charge transfer occurs across both phases.

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Photoinduced electron transfer from anatase to rutile in partially reduced TiO2 (P-25) nanoparticles: An ESR study

Cited by 93 publications

References 21 publications

Water splitting and the band edge positions of TiO2

Water splitting and the band edge positions of TiO2

The nature of interfaces and charge trapping sites in photocatalytic mixed-phase TiO2 from first principles modeling

Photoreaction of Au/TiO2 for hydrogen production from renewables: a review on the synergistic effect between anatase and rutile phases of TiO2

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