Characterisation and reactivity of oxygen species at the surface of metal oxides

Anpo, Masakazu; Costentin, Guylène; Giamello, Elio; Lauron‐Pernot, Hélène; Sojka, Zbigniew

doi:10.1016/j.jcat.2020.10.011

Cited by 94 publications

(54 citation statements)

References 203 publications

(299 reference statements)

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“…On the other hand, when sample is heated at 450 °C, two overlapping broad lines with g = 2.08 and 2.48, and two weak lines with g = 1.94 and 1.85 are visible. Observed EPR spectrum for various layers is in agreement with those described in the literature, especially for the observed oxygen vacancies for g value ~2 [ 36 , 37 ]. The g values for all layers are collected in Table 2 .…”

Section: Resultssupporting

confidence: 90%

Influence of Conditioning Temperature on Defects in the Double Al2O3/ZnO Layer Deposited by the ALD Method

et al. 2021

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In this work, we present the results of defects analysis concerning ZnO and Al2O3 layers deposited by atomic layer deposition (ALD) technique. The analysis was performed by the X-band electron paramagnetic resonance (EPR) spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) methods. The layers were either tested as-deposited or after 30 min heating at 300 °C and 450 °C in Ar atmosphere. TEM and XPS investigations revealed amorphous nature and non-stoichiometry of aluminum oxide even after additional high-temperature treatment. EPR confirmed high number of defect states in Al2O3. For ZnO, we found the as-deposited layer shows ultrafine grains that start to grow when high temperature is applied and that their crystallinity is also improved, resulting in good agreement with XPS results which indicated lower number of defects on the layer surface.

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Section: Resultssupporting

confidence: 90%

Influence of Conditioning Temperature on Defects in the Double Al2O3/ZnO Layer Deposited by the ALD Method

et al. 2021

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“…A very recent review on surface oxygen species on metal oxides reaches similar conclusions; there is no evidence for formation of the atomic oxygen species O – via the redox processes commonly formulated in ionosorption theory (eqs –), and their appearance is associated only with photoexcitation or reductive decomposition of N 2 O. So, direct spectroscopic evidence for one of the key charged surface-adsorbed oxygen species of ionosorption theory, O – , has never been observed experimentally under normal sensor operating conditions.…”

Section: Introductionmentioning

confidence: 94%

Do We Need “Ionosorbed” Oxygen Species? (Or, “A Surface Conductivity Model of Gas Sensitivity in Metal Oxides Based on Variable Surface Oxygen Vacancy Concentration”)

Blackman

2021

ACS Sens.

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The author provides an opinion on direct experimental evidence available to support the "ionosorption theory" often employed to interpret "electrophysical" measurements made during a gas sensing experiment. This article then aims to provide an alternative framework of a "surface conductivity" model based on recent advances in theoretical and experimental investigations in solid state physics, and to use this framework as a guide toward design rules for future improvement of gas sensor performance.

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“…Preparation of thin continuous perovskite layers on iron oxide particles with a proper control of core surface coverage is challenging. Many studies were carried out for identification of surface oxygen species in mixed oxides including perovskites of different compositions and their reactions with catalytic substrates [ 8 , 9 , 10 , 28 , 29 , 30 ]. The effects of surface coverage of oxygen carriers on the oxidation state-distribution-redox reactivity of oxygen atoms at the surface of perovskite shell were not addressed.…”

Section: Introductionmentioning

confidence: 99%

Core-Shell Fe2O3@La1−xSrxFeO3−δ Material for Catalytic Oxidations: Coverage of Iron Oxide Core, Oxygen Storage Capacity and Reactivity of Surface Oxygens

et al. 2021

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A series of Fe2O3@LSF (La0.8Sr0.2FeO3−δ perovskite) core-shell materials (CSM) was prepared by infiltration of LSF precursors gel containing various complexants and their mixtures to nanocrystalline aggregates of hematite followed by thermal treatment. The content of LSF phase and amount of carboxyl groups in complexant determine the percent coverage of iron oxide core with the LSF shell. The most conformal coating core-shell material was prepared with citric acid as the complexant, contained 60 wt% LSF with 98% core coverage. The morphology of the CSM was studied by HRTEM-EELS combined with SEM-FIB for particles cross-sections. The reactivity of surface oxygen species and their amounts were determined by H2-TPR, TGA-DTG, the oxidation state of surface oxygen ions by XPS. It was found that at complete core coverage with perovskite shell, the distribution of surface oxygen species according to redox reactivity in CSM resemble pure LSF, but its lattice oxygen storage capacity is 2–2.5 times higher. At partial coverage, the distribution of surface oxygen species according to redox reactivity resembles that in iron oxide.

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Characterisation and reactivity of oxygen species at the surface of metal oxides

Cited by 94 publications

References 203 publications

Influence of Conditioning Temperature on Defects in the Double Al2O3/ZnO Layer Deposited by the ALD Method

Influence of Conditioning Temperature on Defects in the Double Al2O3/ZnO Layer Deposited by the ALD Method

Do We Need “Ionosorbed” Oxygen Species? (Or, “A Surface Conductivity Model of Gas Sensitivity in Metal Oxides Based on Variable Surface Oxygen Vacancy Concentration”)

Core-Shell Fe2O3@La1−xSrxFeO3−δ Material for Catalytic Oxidations: Coverage of Iron Oxide Core, Oxygen Storage Capacity and Reactivity of Surface Oxygens

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