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Influence of oxygen vacancy on the response properties of TiO2 ultraviolet detector
摘要： In this paper, the effect of sputtering distance between target and substrate (DTS) on the structural, morphological and optical properties of TiO2 films were investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that crystallite size and surface morphology were strongly dependent on DTS. The X-ray photoelectron spectroscopy (XPS) results showed that obvious three peaks including C1S, Ti2p and O1s could be clearly observed and binding energy was 285, 458 and 531 eV, respectively. For each sample, four peaks at about 386, 462, 527 and 595 nm in photoluminescence (PL) spectrum were observed and produced by intrinsic recombination, F center, F+ center and electrons transferred from 3d Ti3+ states to the deep levels OH?, respectively. Finally, photoresponse properties of UV detector based on TiO2 films were further analyzed and TiO2 UV detector prepared by DTS of 80 mm showed a high responsivity of 2.02 ×10-4 A/W and photosensitivity of 32.25, also, exhibited a fast response with a rise time (τr) of 0.98 s and fall time (τf) of 3.14 s.
关键词： UV detector,oxygen vacancy,TiO2 thin films,X-ray photoelectron spectroscopy
更新于2025-09-11 14:15:04
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DFT Calculation about Oxygen Vacancy to Promote Adsorption of a CO Molecule on Single Au-Supported Titanium Dioxide
摘要： The properties and behavior of a single Au atom supported anatase TiO2(001) surface are calculated using density functional theory (DFT) methods. The structures and energies of adsorbed single Au on an anatase TiO2(001) surface with surface oxygen vacancy, as well as subsurface oxygen vacancy, are systematically determined. Initially, the surface threefold coordinated oxygen vacancy adjacent to a single Au atom, rather than the surface two-fold coordinated oxygen vacancy and subsurface threefold coordinated oxygen vacancy, results in more stability for anatase TiO2(001) surface with an Au adatom. Afterwards, the CO molecule is more strongly adsorbed on the single Au-supported TiO2(001) surface with surface threefold coordinated oxygen vacancy when comparing to other structures. This is attributed to the more negatively charged Au single-atom caused by a surface threefold coordinated oxygen vacancy presents concededly active for CO adsorption.
关键词： surface,anatase TiO2,adsorption,oxygen vacancy,Au,CO molecule
更新于2025-09-10 09:29:36
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Polyoxometalates/TiO2 Fenton-like photocatalysts with rearranged oxygen vacancies for enhanced synergetic degradation
摘要： Oxygen vacancy modulation has emerged as a prevalent strategy to improve the performance of heterogeneous catalysts. By far, the impact of oxygen vacancy rearrangement on the efficiency of Fenton-like reaction remains largely unknown. In this paper, Fe-containing polyoxometalates were coupled with defect-rearranged TiO2 to construct defective Fenton-like photocatalysts. Experimental characterizations revealed that defect rearrangement facilitated the interfacial transfer of electrons from TiO2 to polyoxometalate molecules. Fenton-like photocatalysts with rearranged defects exhibited 5 and 3.5 times higher activity for the synergetic degradation of toxic dye and 5-Sulfosalicylic acid than pristine TiO2. This enhancement was ascribed to the beneficial role of oxygen vacancy modulation for activating oxygen and H2O2 molecules into ?O2- and ?OH radicals. Our work provides new opportunities for exploring efficient Fenton-like photocatalysts for environmental remediation.
关键词： Photocatalytic reaction,Polyoxometalates,Fenton-like reaction,Titanium Dioxide,Oxygen vacancy rearrangement
更新于2025-09-10 09:29:36
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Controllable Synthesis of Inverse Opal TiO2-x Photonic Crystals and Their Photoelectric Properties
摘要： In this study, inverse opal TiO2-x photonic crystal (IO-TiO2-x) has been successfully synthesized by a two-step calcination. The whole synthesis is safe and feasible. Additionly, the reduction degree and the structure of IO-TiO2-x can be precisely controlled. A series of IO-TiO2-x samples with different reduction degree were prepared and characterized. The TEM images show that the obtained samples possess a 3D-ordered macroporous inverse opal structure. The reduced Ti atoms/oxygen vacancies were confirmed by Raman and XPS spectra results. All the IO-TiO2-x samples showed better photoelectric properties than those of common TiO2 which indicates great potential to be applied to photoelectric fields. The improvement of photoelectric properties is attributed to the efficient electron-hole separation efficiency induced by moderately reduced Ti atoms/oxygen vacancies. Meanwhile, the 3D-ordered macroporous inverse opal structure and the bandgap are regulated to “capture” more solar energy. This new approach is proves to be a meaningful method to synthesize high-performance TiO2 material.
关键词： reduction,oxygen vacancy,TiO2-x,inverse opal
更新于2025-09-10 09:29:36
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Effective protect of oxygen vacancies in carbon layer coated black TiO2-x/CNNS hetero-junction photocatalyst
摘要： Carbon layer coated black TiO2-x/g-C3N4 nanosheets (C@TiO2-x/CNNS) heterojunction photocatalysts were successfully prepared via a polydopamine dopamine carbonization route for the first time. It was found that the hydrogen evolution rate of C@TiO2-x/CNNS was 417.2 μmol h-1 g-1 under visible light irradiation, which was much higher than that of other prepared photocatalysts in solar water splitting process at the same conditions, and obvious decrease in catalytic activity can be observed after three recycles. The formation of carbon layer on the surface of TiO2-x can effectively protect Ti3+ and oxygen vacancies (Ovs) from oxidation by air and dissolved O2, afterwards much more Ti3+/Ovs are exsited, which can serve as charge carrier traps to inhibit the recombination of light-excited electrons-holes. Therefore, C@TiO2-x/CNNS showed a highly conductivity, rapidly effective electron-hole separation and lower transmission resistance comprehensive consideration of the advantages of carbon layer and hetero-junction, which are of great benefit to the improvement of photocatalytic performance. Hence, a new catalytic tactic namely layer-protection effect was founded and this strategy for boosting hydrogen evolution and protection Ti3+/Ovs may give us some hints on the design of photocatalytic systems.
关键词： black TiO2,visible light H2 evolution,g-C3N4 nanosheet,carbon layer protect oxygen vacancy
更新于2025-09-10 09:29:36
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Two-step Synthesis of Laminar Vanadate via a Facile Hydrothermal Route and Enhancing the Photocatalytic Reduction of CO2 into Solar Fuel through Tuning the Oxygen Vacancies by in situ Vacuum Illumination Treatment
摘要： Monoclinic LaVO4, tetragonal CeVO4 and monoclinic Pb2V2O7 with laminar structures composed of nanosheets have been successfully fabricated using a two-step facile hydrothermal route. The narrow-bandgap LaVO4, CeVO4 and Pb2V2O7 vanadate exhibited photocatalytic activity towards the photoreduction of CO2 into C2H5OH in the liquid phase. The existence of oxygen vacancies on LaVO4 surface further enhanced the photocatalytic activity for photoreduction of CO2 into CO in gas phase, which can be easily obtained using a vacuum illumination treatment. The EPR, PL and FTIR results indicated that oxygen vacancies are beneficial to the separation of electrons by prolonging the lifetime of the photogenerated electrons and enhancing the chemisorption of CO2 on the photocatalyst surface.
关键词： Laminar structure,Photocatalytic reduction of CO2,Vanadate,Oxygen vacancy,Photocatalytic activity
更新于2025-09-10 09:29:36
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Effect of the Gamma-Ray Irradiation on the Electric and Optical Properties of SrTiO3 Single Crystals
摘要： We investigated the visible emission property of SrTiO3 (STO) single crystals irradiated with gammy-ray (γ-ray) at various total doses up to 900 kGy. The electric and optical absorption properties of the irradiated STO samples were hardly changed with the γ-ray irradiation, compared with those of un-irradiated STO. In contrast, the visible emission near 550 nm increased with the γ-ray dose increasing. While the development of the visible emission was indicative of the increase of oxygen vacancies inside STO by the γ-ray irradiation, the newly generated oxygen vacancies were not significantly harmful to the electric and optical properties of STO. We concluded that the STO single crystal should have a good tolerance against the damage by the γ-ray irradiation.
关键词： Gamma-ray irradiation,Photoluminescence,Oxygen vacancy,SrTiO3 single crystal
更新于2025-09-10 09:29:36
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Se—assisted synthesis of WO <sub/>3?x</sub> nanowires and its intrinsic metallicity
摘要： One dimensional WO3?x nanowires were successfully synthesized by a chemical vapor deposition method under a catalysis effect of non-metal selenium at an atmosphere pressure. The morphology ad structural characteristics were investigated by scanning electron microscopy (SEM), atom force microscopy (AFM), and transmission electron microscopy (TEM). Furthermore, X-ray photoelectron spectrum analysis con?rms existence of the oxygen vacancies in WO3?x nanowires. Based on the above results, a possible growth mechanism was proposed. The oxygen vacancy induced metallic nature of WO3?x nanowires was also con?rmed by the single-nanowire electrical measurements.
关键词： oxygen vacancy,metallic,WO3?x nanowires,chemical vapor deposition
更新于2025-09-09 09:28:46
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[IEEE 2018 Iranian Conference on Electrical Engineering (ICEE) - Mashhad (2018.5.8-2018.5.10)] Electrical Engineering (ICEE), Iranian Conference on - Investigating the Electronic Properties of Oxygen Vacancies in Anatase TiO2: An Ab Initio Study
摘要： Metal oxide dielectrics are known as promising candidates for resistive switching or memristor applications. TiO2 has been shown to be one of the favorites for the implementation of resistive switching devices. The mobile oxygen vacancies in TiO2 are recognized as the main source of resistive switching behavior. Therefore, the investigation of atomic scale properties of oxygen vacancies is of crucial importance for the description of microscopic phenomena leading to the resistive switching behavior. In the present work we employed standard DFT within the GGA approximation as well as GGA+U correction to investigate the electronic properties of oxygen vacancies in anatase phase of TiO2. We show that the Hubbard- like term (U) is essential for the correct description of the electronic properties. The defect formation energies at different charged states and the charge transition levels are calculated for different values of U-term. It has been shown that a value of U=3.5 eV is the best choice to obtain reasonable results for the band gap as well as the position of induced defect levels, at same time. Moreover, we show that the q=+2 charged state is the energetically most favorable state for the oxygen vacancy in TiO2.
关键词： metal oxides,DFT,resistive switching,charge transition levels,oxygen vacancy,Hubbard-like term,anatase TiO2
更新于2025-09-09 09:28:46
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The Nature of the Oxygen Vacancy in Amorphous Oxide Semiconductors: Shallow Versus Deep
摘要： Using first-principles calculation, we investigate the nature of oxygen vacancy (VO), namely shallow versus deep, in the amorphous oxide semiconductor InGaZnO4 (a-IGZO), which has not been fully clarified despite its technological importance. Oxygen-deficient amorphous models are generated through the hybrid functional molecular dynamics (MD) simulations that allow for finding stable VO configurations while minimizing computational approximations. From eight independent models, we consistently find that VO serves as the shallow donor, increasing the Fermi level above the conduction band minimum. For comparison purpose, we also generate deep VO models by charging the system during MD simulations. It is found that deep VO is higher in the formation energy than shallow VO, confirming that shallow VO is the preferred type of oxygen vacancies in a-IGZO.
关键词： hybrid functional,computational physics,InGaZnO4,oxygen vacancy,density functional theory
更新于2025-09-09 09:28:46