The nature of paramagnetic defects in tin (IV) oxide

Ivanovskaya, M. I.; Ovodok, Evgeni; Golovanov, V.

doi:10.1016/j.chemphys.2015.05.023

Cited by 27 publications

(15 citation statements)

References 42 publications

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“…After the alkali etchingp rocess, the peak signal of etched sample E3 positioned at g % 1.999 is much strongert han that of the pristine one, whichc an be ascribed to the formation of single-electron trapped oxygen vacancies (V O C). [27,28] Oxygen vacancies at the surfaceo fcatalyst can probably act as trapping centers for electrons and similarr esults were also reported for N-TiO 2 -a nd SnO 2 -based semiconductors, owing to the complexes of oxygen vacancies. [27,28] The results showt hat Bi 2 WO 6 in the NaOH solution is undergoing an etching process and the possible dissolved processi nduced oxygen vacancies on the BiÀO layer as evidenced by the increased intensity of BiÀOb onding in E3 and the EPR signal.…”

Section: Resultssupporting

confidence: 69%

“…[27,28] Oxygen vacancies at the surfaceo fcatalyst can probably act as trapping centers for electrons and similarr esults were also reported for N-TiO 2 -a nd SnO 2 -based semiconductors, owing to the complexes of oxygen vacancies. [27,28] The results showt hat Bi 2 WO 6 in the NaOH solution is undergoing an etching process and the possible dissolved processi nduced oxygen vacancies on the BiÀO layer as evidenced by the increased intensity of BiÀOb onding in E3 and the EPR signal. Raman spectra were also collected to study the oxygen vacancies effecto nt he surface structure of Bi 2 WO 6Àx ,a nd the results are shown in Figure 5.…”

Section: Resultssupporting

confidence: 69%

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Generation of Oxygen Vacancy and OH Radicals: A Comparative Study of Bi₂WO₆ and Bi₂WO_6−x Nanoplates

et al. 2015

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A comparative study of visible‐light‐responsive Bi2WO6 and oxygen‐deficient Bi2WO6−x nanoplates was conducted. The formation of oxygen vacancy resulted in the band gap narrowing of oxygen‐deficient Bi2WO6−x, through an elevation of both of the conduction and valence band positions. FTIR spectra revealed that much more surface hydroxyl groups have been detected after the etching process. The scavengers tests confirmed the generation of ⋅OH radicals during photochemical reaction for Bi2WO6−x, whereas no .OH radicals can be detected for pure Bi2WO6. The photocatalytic activities of optimized Bi2WO6−x on the decomposition of Rhodamine B (RhB) was three times as high as that of pure Bi2WO6. The improvement of photocatalytic activity on degradation of RhB and phenol can be ascribed to the synergistic effect of oxygen deficiency‐induced band shifts, together with the large quantities of surface hydroxyl groups providing active sites for the generation of OH radicals (.OH).

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Section: Resultssupporting

confidence: 69%

Section: Resultssupporting

confidence: 69%

Generation of Oxygen Vacancy and OH Radicals: A Comparative Study of Bi₂WO₆ and Bi₂WO_6−x Nanoplates

et al. 2015

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“…The increasing concentration of VO − in SnO2, TiO2 and WO3 agrees with the renowned oxygen deficiency of these compounds, e.g., the existence of Magneli phases (TinO2n−1) and numerous WO3-x phases [99]. The stability of oxygen vacancies in MOS with high EM-O can be explained by the relatively high electronegativity of the cations which can trap the loosely bound electrons, and, thus, be reduced to Sn 2+ (and Sn 3+ [100]), Ti 3+ , W 5+ (and W 4+ ), respectively. The formation of oxygen vacancy reduces the coordination number of cations, which is favorable for stronger (more covalent) bonding of electronegative cations with oxygen anions.…”

Section: Donor Sites (Oxygen Vacancies)supporting

confidence: 69%

“…The oxidation states and coordination environments of metal cations, oxygen anions and surface oxygen species can be obtained by standard techniques of materials characterization, e.g., X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS), Mossbauer spectroscopy (if applicable for given cations) [45,100,146]. Fourier-transformed infrared (FTIR) spectroscopy is inevitable for the detection of polar adsorbates that have the functional groups with O-H, N-O, N-H, C-H, C-O, S-O bonds, etc.…”

Section: Conflicts Of Interestmentioning

confidence: 99%

The Key Role of Active Sites in the Development of Selective Metal Oxide Sensor Materials

Marikutsa

Rumyantseva

Константинова

et al. 2021

Sensors

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Development of sensor materials based on metal oxide semiconductors (MOS) for selective gas sensors is challenging for the tasks of air quality monitoring, early fire detection, gas leaks search, breath analysis, etc. An extensive range of sensor materials has been elaborated, but no consistent guidelines can be found for choosing a material composition targeting the selective detection of specific gases. Fundamental relations between material composition and sensing behavior have not been unambiguously established. In the present review, we summarize our recent works on the research of active sites and gas sensing behavior of n-type semiconductor metal oxides with different composition (simple oxides ZnO, In2O3, SnO2, WO3; mixed-metal oxides BaSnO3, Bi2WO6), and functionalized by catalytic noble metals (Ru, Pd, Au). The materials were variously characterized. The composition, metal-oxygen bonding, microstructure, active sites, sensing behavior, and interaction routes with gases (CO, NH3, SO2, VOC, NO2) were examined. The key role of active sites in determining the selectivity of sensor materials is substantiated. It was shown that the metal-oxygen bond energy of the MOS correlates with the surface acidity and the concentration of surface oxygen species and oxygen vacancies, which control the adsorption and redox conversion of analyte gas molecules. The effects of cations in mixed-metal oxides on the sensitivity and selectivity of BaSnO3 and Bi2WO6 to SO2 and VOCs, respectively, are rationalized. The determining role of catalytic noble metals in oxidation of reducing analyte gases and the impact of acid sites of MOS to gas adsorption are demonstrated.

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“…Assuming that the oxygen vacancies at the interface between different tin oxide phases can work as paramagnetic trapping centres for electrons [23], we used EPR spectroscopy to look for the signal of paramagnetic oxygen vacancies (OV) in the SnO/SnO 2-δ /SnO 2 samples. This method is known as a sensitive tool for the characterization of the paramagnetic centres on various oxide surfaces [24].…”

Section: Resultsmentioning

confidence: 99%

Nonstoichiometric tin oxide films: study by X-ray diffraction, Raman scattering and electron paramagnetic resonance

Adamchuk¹,

Ксеневич²,

Poklonski³

et al. 2020

physics

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Nonstoichiometric SnO/SnO2/SnO2−δ films were fabricated by DC magnetron sputtering and reactive DC magnetron sputtering of tin target with further 2-stage temperature annealing of synthesized materials. X-ray diffraction analysis, Raman spectroscopy and electron paramagnetic resonance (EPR) spectroscopy were employed to study the influence of oxygen content in the plasma during the sputtering process and the temperature of annealing on the stoichiometric and phase composition of synthesized films. It was found that the tin monoxide phase prevailed in the films fabricated by DC magnetron sputtering in the argon plasma followed by a 2-stage annealing process. Nanocrystalline films containing both tin monoxide and tin dioxide were synthesized when reactive magnetron sputtering with a small content of oxygen (of about 1 vol.%) was used. The increase of oxygen content in the plasma to the value of about 2 vol.% leads to the formation of amorphous films. The intensity of the Raman peaks inherent in SnO2 vibration modes was found to depend on the content of the tin monoxide phase in the films. This effect can be attributed to the dissipative transition of electronic excitation from tin monoxide to tin dioxide nanocrystallites.

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The nature of paramagnetic defects in tin (IV) oxide

Cited by 27 publications

References 42 publications

Generation of Oxygen Vacancy and OH Radicals: A Comparative Study of Bi₂WO₆ and Bi₂WO_6−x Nanoplates

Generation of Oxygen Vacancy and OH Radicals: A Comparative Study of Bi₂WO₆ and Bi₂WO_6−x Nanoplates

The Key Role of Active Sites in the Development of Selective Metal Oxide Sensor Materials

Nonstoichiometric tin oxide films: study by X-ray diffraction, Raman scattering and electron paramagnetic resonance

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The nature of paramagnetic defects in tin (IV) oxide

Cited by 27 publications

References 42 publications

Generation of Oxygen Vacancy and OH Radicals: A Comparative Study of Bi2WO6 and Bi2WO6−x Nanoplates

Generation of Oxygen Vacancy and OH Radicals: A Comparative Study of Bi2WO6 and Bi2WO6−x Nanoplates

The Key Role of Active Sites in the Development of Selective Metal Oxide Sensor Materials

Nonstoichiometric tin oxide films: study by X-ray diffraction, Raman scattering and electron paramagnetic resonance

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Product

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Generation of Oxygen Vacancy and OH Radicals: A Comparative Study of Bi₂WO₆ and Bi₂WO_6−x Nanoplates

Generation of Oxygen Vacancy and OH Radicals: A Comparative Study of Bi₂WO₆ and Bi₂WO_6−x Nanoplates