Synchrotron radiation studies of H2O adsorption on TiO2(110)

Kurtz, Richard L.; Stockbauer, Roger; Madey, Theodore E.; Román, E.; Segovia, JoséL. de

doi:10.1016/0167-2584(89)90745-7

Cited by 143 publications

(298 citation statements)

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“…On MgO(100) [343] and α-Fe 2 O 3 (0001) [136,349], water was found to dissociate both on regular and defective surfaces and a correlation between the defect concentration and amount of dissociative adsorption was found. On other oxides, the role of defects for the dissociative adsorption is not clear, because water dissociation occurs both on ordered and defective surfaces with a similar rates, as on V 2 O 3 (047) [135], TiO 2 (110) [355], TiO 2 (001) [356] and SnO 2 (110) [350]. These studies suggest that defect sites can mostly dissociate water, in agreement with many studies performed on polycrystalline oxide materials [3].…”

Section: Discussionsupporting

confidence: 76%

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Weiß

Ranke

2002

Progress in Surface Science

579

610

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Metal-oxide based catalysts are used for many important synthesis reactions in the chemical industry. A better understanding of the catalyst operation can be achieved by studying elemantary reaction steps on well-defined model catalyst systems. For the dehydrogenation of ethylbenzene to styrene in the presence of steam both unpromoted and potassium promoted iron-oxide catalysts are active. Here we review the work done over unpromoted single-crystalline FeO(111), Fe 3 O 4 (111) and α-Fe 2 O 3 (0001) films grown epitaxially on Pt(111) substrates. Their geometric and electronic surface structures were characterized by STM, LEED, electron microscopy and electron spectroscopic techniques. In an integrative approach, the interaction of water, ethylbenzene and styrene with these films was investigated mainly by thermal desorption and photoelectron emission spectroscopy. The adsorptiondesorption energetics and kinetics depend on the oxide surface terminations and are correlated to the electronic structures and acid-base properties of the corresponding oxide phases, which reveal insight into the nature of the active sites and into the catalytic function of semiconducting oxides in general. Catalytic studies, using a batch reactor arrangement at high gas pressures and post reaction surface analysis, showed that only α-Fe 2 O 3 (0001) containing surface defects is catalytically active, whereas Fe 3 O 4 (111) is always inactive. This can be related to the elementary adsorption and desorption properties observed in ultrahigh vacuum, which indicates that the surface chemical properties of the iron-oxide films do not change significantly across the "pressure-gap". A model is proposed according to which the active site involves a regular acidic surface sites and a defect site next to it. The results on metal-oxide surface chemistry also have implications for other fields, such as environmental science, biophysics and chemical sensors.-2 -"2kyEi9FYSQjBVrZxIPQ.FHIAC_WRa02_review.doc", Datum: 19.02.03

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Section: Discussionsupporting

confidence: 76%

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Weiß

Ranke

2002

Progress in Surface Science

579

610

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“…In contrast, the hybrid PBE0 calculation predicts a band gap of 4.0 eV and two gap states at 1.2 and 1.0 eV below the conduction band. Our PBE0 results are in reasonable agreement with the experimentally observed gap state 0.8 eV below the conduction band 63 and previous DFT+ U ͑Ref. 31͒ and B3LYP calculations.…”

Section: Cluster Model For the Metal-oxide Interfacesupporting

confidence: 81%

Modeling the noble metal/TiO2 (110) interface with hybrid DFT functionals: A periodic electrostatic embedded cluster model study

Ammal

Heyden

2010

The Journal of Chemical Physics

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Articles you may be interested inEmbedded cluster density functional and second-order Møller-Plesset perturbation theory study on the adsorption of N2 on the rutile (110) This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation. The interaction of Au n and Pt n ͑n=2,3͒ clusters with the stoichiometric and partially reduced rutile TiO 2 ͑110͒ surfaces has been investigated using periodic slab and periodic electrostatic embedded cluster models. Compared to Au clusters, Pt clusters interact strongly with both stoichiometric and reduced TiO 2 ͑110͒ surfaces and are able to enhance the reducibility of the TiO 2 ͑110͒ surface, i.e., reduce the oxygen vacancy formation energy. The focus of this study is the effect of Hartree-Fock exchange on the description of the strength of chemical bonds at the interface of Au/Pt clusters and the TiO 2 ͑110͒ surface. Hartree-Fock exchange helps describing the changes in the electronic structures due to metal cluster adsorption as well as their effect on the reducibility of the TiO 2 surface. Finally, the performance of periodic embedded cluster models has been assessed by calculating the Pt adsorption and oxygen vacancy formation energies. Cluster models, together with hybrid PBE0 functional, are able to efficiently compute reasonable electronic structures of the reduced TiO 2 surface and predict charge localization at surface oxygen vacancies, in agreement with the experimental data, that significantly affect computed adsorption and reaction energies.

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“…34 Free electrons could thus be produced during irradiation, and these free electrons could induce DEA of CH 3 OH. 51 However, the density of electron states near the Fermi level (E F ) of reduced TiO 2 (110) surfaces is quite small, 52,53 and the density of free electrons would be very low. Furthermore, DEA of gas-phase CH 3 OH is generally observed for electron attachment resonances that lie >6 eV.…”

Section: ■ Discussionmentioning

confidence: 99%

Strong Photon Energy Dependence of the Photocatalytic Dissociation Rate of Methanol on TiO₂(110)

Yang

Ren

et al. 2013

J. Am. Chem. Soc.

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Photocatalytic dissociation of methanol (CH 3 OH) on a TiO 2 (110) surface has been studied by temperature programmed desorption (TPD) at 355 and 266 nm. Primary dissociation products, CH 2 O and H atoms, have been detected. The dependence of the reactant and product TPD signals on irradiation time has been measured, allowing the photocatalytic reaction rate of CH 3 OH at both wavelengths to be directly determined. The initial dissociation rate of CH 3 OH at 266 nm is nearly 2 orders of magnitude faster than that at 355 nm, suggesting that CH 3 OH photocatalysis is strongly dependent on photon energy. This experimental result raises doubt about the widely accepted photocatalysis model on TiO 2 , which assumes that the excess potential energy of charge carriers is lost to the lattice via strong coupling with phonon modes by very fast thermalization and the reaction of the adsorbate is thus only dependent on the number of electron−hole pairs created by photoexcitation. ■ INTRODUCTIONSince the discovery of the photocatalytic splitting of water (H 2 O) on TiO 2 electrodes by Fujishima and Honda in 1972, 1 tremendous research efforts have gone into understanding the fundamental processes and in enhancing the photocatalytic efficiency of TiO 2 . 2 These efforts have been driven by the potential benefits to renewable energy, energy storage, and environmental cleanup. 3,4 In particular, TiO 2 has attracted much attention because of its applications in heterogeneous catalysis, photocatalysis, solar energy devices, etc. 5−14In an ideal photocatalyst, all photon energy invested in the generation of charge carriers would be available for redox chemistry. The higher the potential energy of the electron (or hole) the more reductive (or oxidative) capacity there is.15 But charge carrier thermalization is rapid. For example, Gundlach and co-workers used two photon photoemission (2PPE) to track thermalization following electron injection from two dyes adsorbed on rutile TiO 2 (110). 16,17 Fast initial decay of the 2PPE signal resulting from thermalization of the injected electron occurred on the 10 fs time scale. This result suggests that excess potential energy is lost to the lattice via strong coupling with phonon modes, thus reducing the potential advantage gained by the specificity in the absorption event. Additional evidence for the rapid thermalization of electrons comes from photoemission spectra of Ag clusters on rutile TiO 2 (110) 18 as a function of injection electron energy and from photoluminescence spectra of rutile TiO 2 (110) 19,20 with 3.35 eV photon irradiation. In both these studies, a constant energy of the emitted photons was observed (at and below the band gap energy3.05 eV), independent of the energy of the exciting electron or photon. Furthermore, experimental investigations indicate that the photodesorption yield and translational energy of O 2 from an O 2 -adsorbed TiO 2 (110) surface are independent of the excitation photon energy above 3.4 eV, but instead depend on the photon flux. 21...

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Synchrotron radiation studies of H2O adsorption on TiO2(110)

Cited by 143 publications

References 0 publications

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Modeling the noble metal/TiO2 (110) interface with hybrid DFT functionals: A periodic electrostatic embedded cluster model study

Strong Photon Energy Dependence of the Photocatalytic Dissociation Rate of Methanol on TiO₂(110)

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Synchrotron radiation studies of H2O adsorption on TiO2(110)

Cited by 143 publications

References 0 publications

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Modeling the noble metal/TiO2 (110) interface with hybrid DFT functionals: A periodic electrostatic embedded cluster model study

Strong Photon Energy Dependence of the Photocatalytic Dissociation Rate of Methanol on TiO2(110)

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Strong Photon Energy Dependence of the Photocatalytic Dissociation Rate of Methanol on TiO₂(110)