Characterization and Reactivity of Molecular Oxygen Species on Oxide Surfaces

Che, M.; Tench, A. J.

doi:10.1016/s0360-0564(08)60439-3

Cited by 590 publications

(492 citation statements)

References 392 publications

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“…6a) shows the typical features 40 already reported for this species 57 with the low field component of the g tensor at g zz = 2.039 (the z direction corresponds to the oxygen internuclear axis) and with an anomalous value of the high field component that, instead of laying around the free spin value (g e =2.0023) as expected by the ionic model of adsorbed 45 superoxide 58 , is at g xx =2.010 and very close to g yy so producing a sort of unresolved perpendicular line. The anomalous value of g xx shown by superoxide ions on cerium dioxide was already discussed 57,59 in terms of a model involving some degree of covalence in the interaction of adsorbed oxygen with the 4f 50 cerium orbitals and causing deviations from the purely ionic model.…”

Section: Surface Reactivity With Oxygen and Epr Spectroscopysupporting

confidence: 61%

“…The same experiment related to figure 6b was recorded using 17 O enriched oxygen in order to observe a hyperfine structure due to the 17 O nucleus (nuclear spin I=5/2). Such hyperfine structure (not reported for sake of brevity) 20 indicates the presence of two magnetically equivalent oxygen atoms in the superoxide mojety 58 Summarizing the superoxide species formed by O 2 adsorption on pre-reduced mixed materials ( Fig. 6b and 6c) have different g zz values and therefore different spectral profile from those formed 30 on the bare oxide ( Fig.…”

Section: Surface Reactivity With Oxygen and Epr Spectroscopymentioning

confidence: 97%

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The interaction of oxygen with the surface of CeO₂–TiO₂mixed systems: an example of fully reversible surface-to-molecule electron transfer

Gionco

Giamello

Mino

et al. 2014

Phys. Chem. Chem. Phys.

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Mixed CeO 2 -TiO 2 systems have been synthesized using the sol-gel technique in a symmetric range of 5 nominal compositions (0.1, 0.5, 0.9 CeO 2 molar fraction respectively). The solid materials have been characterised using a variety of diffractometric and spectroscopic techniques. The intimate contact between the two components during the synthesis leads to heterogeneous systems which are based on the presence, beside the two individual oxide phases, of a mixed phase of a cerium titanate (Ce 2 Ti 2 O 7 , pyrochlore structure) which contains Ce 3+ ions imparting particular optical properties to the solid 10 (pronounced red shift with respect to the band gap transition of the two oxides). Ce 3+ ions are present at the surface of the systems together with tetravalent Ce and Ti ions. The mixed solids can be reduced by annealing under vacuum and, upon reoxidation in mild conditions with O 2 , form superoxide species adsorbed on Ce 4+ which have, as already reported for low loading CeO 2 -TiO 2 systems, peculiar spectroscopic properties with respect to superoxide adsorbed on bare cerium dioxide.

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Section: Surface Reactivity With Oxygen and Epr Spectroscopysupporting

confidence: 61%

Section: Surface Reactivity With Oxygen and Epr Spectroscopymentioning

confidence: 97%

The interaction of oxygen with the surface of CeO₂–TiO₂mixed systems: an example of fully reversible surface-to-molecule electron transfer

Gionco

Giamello

Mino

et al. 2014

Phys. Chem. Chem. Phys.

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“…The intensities of four spectra bands were widely affected by ozone interaction with Z-78 zeolite surface. The first observed band falls in the range of adsorbed peroxide (Z-AlÁ Á ÁO 2 ) as it has been detected between 640-970 cm À1 on oxide surfaces by other researchers [24]. The band at 1040-1060 cm À1 , at 1080 cm À1 and at 1140 cm À1 could be related to adsorbed molecular ozone on weak Lewis acid sites [25].…”

Section: 2supporting

confidence: 54%

Role of Lewis acid sites of ZSM-5 zeolite on gaseous ozone abatement

Brodu

Manero

Andriantsiferana

et al. 2013

Chemical Engineering Journal

102

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 9735 We report the role played by acidic surface sites of ZSM-5 on ozone removal. Ozone removal is mainly due to ozone decomposition on mild/strong Lewis acid sites. Adsorbed oxygen species appear on ZSM-5 surface because of ozone decomposition. Keywords:Acidic sites Chemical surface properties Lewis acid sites Ozone Synthetic zeolites ZSM-5 zeolite a b s t r a c t In this work, chemical interactions between ozone and zeolite surface active sites are studied in order to propose a process for gaseous ozone removal. Synthetic ZSM-5 zeolites with three different Si/Al 2 ratios and similar specific surface areas and microporous volumes were used in this study. Zeolite samples were characterised using Fourier Transform InfraRed spectroscopy (FTIR) and pyridine sorption IR studies in order to determine acidic site concentrations and strength. Ozone removal experiments were conducted in a quartz fixed-bed flow reactor, at 20°C and 101 kPa. Experiments using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) were conducted in order to identify adsorbed ozone and/or adsorbed oxygen species on zeolite surface. Pyridine IR measurements evidence two kinds of Lewis acid sites induced by extra-framework aluminium species and electronic aluminium defaults inside zeolite structure. Results obtained here evidence the important role of acidic surface sites of ZSM-5 zeolite on gaseous ozone removal. The total amount of removed ozone is found to be directly proportional to the total content of Lewis acid sites. DRIFTS experiments exhibit two bands around 800 and 1400 cm À1 that could correspond to adsorbed oxygen species linked to zeolite surface. DRIFTS experiments also exhibit a band around 1100 cm À1 that correspond to adsorbed ozone on the zeolite surface. Gaseous ozone removal using ZSM-5 zeolite could be largely attributed to ozone decomposition on Lewis acid sites and also to ozone adsorption on the surface of the zeolites.

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“…The same mechanism might also apply for the albite-bearing control site soil. Also, metal superoxides and peroxides may be continuously photogenerated in all soils because TiO 2 , Feoxides and Fe-Ti-oxides-present in the tested soils and typical of desert soils 45 -are known to be involved in the photogeneration process of O 2 Á À (refs [13][14][15]17,36 …”

Section: Discussionmentioning

confidence: 99%

“…Photogenerated ROS have been identified in laboratory studies on mineral oxides (mainly TiO 2 ) exposed to ultraviolet radiation: atomic oxygen radical anion (O Á À ), ozone radical anion (O 3 Á À , and possibly O 4 Á À ), O 2 Á À and Á OH [13][14][15] . The postulated process in these studies involves ultraviolet-induction of electron mobilization from the oxide surface and its subsequent capture by O 2 to form oxygen radical surface adsorbates 16 .…”

mentioning

confidence: 99%

Evidence for photochemical production of reactive oxygen species in desert soils

et al. 2015

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The combination of intense solar radiation and soil desiccation creates a short circuit in the biogeochemical carbon cycle, where soils release significant amounts of CO 2 and reactive nitrogen oxides by abiotic oxidation. Here we show that desert soils accumulate metal superoxides and peroxides at higher levels than non-desert soils. We also show the photogeneration of equimolar superoxide and hydroxyl radical in desiccated and aqueous soils, respectively, by a photo-induced electron transfer mechanism supported by their mineralogical composition. Reactivity of desert soils is further supported by the generation of hydroxyl radical via aqueous extracts in the dark. Our findings extend to desert soils the photogeneration of reactive oxygen species by certain mineral oxides and also explain previous studies on desert soil organic oxidant chemistry and microbiology. Similar processes driven by ultraviolet radiation may be operating in the surface soils on Mars.

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Characterization and Reactivity of Molecular Oxygen Species on Oxide Surfaces

Cited by 590 publications

References 392 publications

The interaction of oxygen with the surface of CeO₂–TiO₂mixed systems: an example of fully reversible surface-to-molecule electron transfer

The interaction of oxygen with the surface of CeO₂–TiO₂mixed systems: an example of fully reversible surface-to-molecule electron transfer

Role of Lewis acid sites of ZSM-5 zeolite on gaseous ozone abatement

Evidence for photochemical production of reactive oxygen species in desert soils

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Characterization and Reactivity of Molecular Oxygen Species on Oxide Surfaces

Cited by 590 publications

References 392 publications

The interaction of oxygen with the surface of CeO2–TiO2mixed systems: an example of fully reversible surface-to-molecule electron transfer

The interaction of oxygen with the surface of CeO2–TiO2mixed systems: an example of fully reversible surface-to-molecule electron transfer

Role of Lewis acid sites of ZSM-5 zeolite on gaseous ozone abatement

Evidence for photochemical production of reactive oxygen species in desert soils

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The interaction of oxygen with the surface of CeO₂–TiO₂mixed systems: an example of fully reversible surface-to-molecule electron transfer

The interaction of oxygen with the surface of CeO₂–TiO₂mixed systems: an example of fully reversible surface-to-molecule electron transfer