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Oxygen Vacancy-Rich Ultrathin Sulfur-Doped Bismuth Oxybromide Nanosheet as a Highly Efficient Visible-Light Responsive Photocatalyst for Environmental Remediation
摘要： Designing ultrathin two-dimensional (2D) defective materials and metal-free doped materials as photocatalysts both have received enormous attentions in the field of environmental remediation due to their great potential for removing colorless contaminants. However, whether the synergism of defects and metal-free doping exists and the corresponding oxidative mechanism is unclear, which retard further developments of high performance catalysts. Here, a novel oxygen vacancy (OV)-rich ultrathin sulfur-doped BiOBr nanosheet (BB-xS) was synthesized through a facile one-step solvothermal method. Under visible light irradiation, the optimal BB-5S sample exhibited 98% degradation efficiency of 4-chlorophenol (4-CP) within 120min, which was 4.9 and 18.0 times greater than that of pristine ultrathin BiOBr and oxygen vacancy-poor sulfur-doped BiOBr, respectively. Also, this excellent photoactivity could extend to other colorless organic contaminants, such as bisphenol analogues and sulfonamides, verifying the universal applicability of BB-xS. Based on experimental results and density functional theory (DFT) calculations, it was manifested that a sub-band was generated via the synergistic effect of oxygen vacancies and sulfur doping, and it greatly enhanced the visible-light absorption capability and suppressed the photoinduced charge recombination, which would be beneficial to improve the photocatalytic activity. Additionally, the corresponding photocatalytic degradation pathway of 4-CP was also proposed. This work can provide a new protocol for the design and construction of highly active photocatalysts toward environmental remediation.
关键词： photocatalytic degradation,Ultrathin two-dimensional nanosheets,sulfur-doped,oxygen vacancy,colorless organic contaminants
更新于2025-09-09 09:28:46
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Synthesis of Self-Gravity Settling Faceted-Anatase TiO2 with Dominant {010} Facets for the Photocatalytic Degradation of Acetaminophen and Study of the Type of Generated Oxygen Vacancy in Faceted-TiO2
摘要： In this study, faceted TiO2, predominately exposed with {010} facets (T-{010}), was synthesized with a two-step hydrothermal reaction and used for the degradation of acetaminophen (ACE) in an aqueous solution. T-{010} showed considerable photocatalytic reactivity, and its easy-settling (gravity-settling, ~97% of T-{010} settled after 30 min) property demonstrated acceptable reusability. A solid-state chemical reduction approach (NaBH4) at a mild temperature (300 ?C) was used for generation of an oxygen vacancy in T-{010} and P25 (commercial TiO2). The oxygen vacancy concentrations of the samples were investigated by electron paramagnetic resonance (EPR). It was also found that NaBH4 reduction induced the generation of both surface and subsurface Ti3+ on colored P25, but only surface Ti3+ species were formed on colored T-{010}. The prepared colored TiO2 samples were successfully used for photocatalytic degradation of ACE in an aqueous solution under visible light illumination.
关键词： photocatalytic degradation,visible light,{010} facet,oxygen vacancy,settling
更新于2025-09-09 09:28:46
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One-step synthesis of hollow BaZrO3 nanocrystals with oxygen vacancies for photocatalytic hydrogen evolution from pure water
摘要： It is very challenging to synthesize perovskite oxides with controlled morphology and defect states at the same time. In this work, the BaZrO3 hollow nanostructures with oxygen vacancies were facilely synthesized through one-step solvothermal method using ethylenediamine (EDA) as solvent. The as-synthesized BaZrO3 could split pure water into H2 without addition of sacrificial agent under UV light irradiation. The photocatalytic H2 production rate is about 15 times than that of the commercial BaZrO3 (BZO-C). It is believed that the presence of oxygen vacancies and the hollow morphology made contribution to the improvement of photocatalytic performance. This work provides a reference for microstructure and defect modification of photocatalysts at the same time to enhance the photocatalytic performance.
关键词： BaZrO3,Photocatalysis,Oxygen vacancy,Pure water,Hollow structure
更新于2025-09-09 09:28:46
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Preparation and Photocatalytic Activities of Black TiO <sub/>2</sub> in Vacuum and Ambient Temperature Environment
摘要： The preparation conditions are important for the structure and properties of black TiO2. In this paper, the black rutile TiO2 with a particle size of approximately 5 nm was prepared in vacuum by the infrared nano-second laser sputtering deposition method. The study results indicated that the prepared black TiO2 exhibited high light absorption from UV to near-infrared region. The lattice distortion and Ti3+ were responsible for the upward shift in the valance band, and the oxygen vacancy states were determined to be located about 0.7–1.18 eV under the conduction band, narrowing the band gap of TiO2 from 3.2 eV to 2.1 eV. Although the black TiO2 exhibited strong adsorption effects within the full spectrum and had a higher free carrier density, the presence of excess oxygen defects resulted in a higher recombination rate of the photo electron–hole pairs, which induced a poor photocatalytic performance of the black TiO2. This work facilitates the understanding of the mechanisms mechanism of black TiO2 formation via laser ablation, and emphasized the need for the controllability and quanti?cation of oxygen vacancies.
关键词： Vacuum,Laser Ablation,Oxygen Vacancy,Photocatalytic Activity,Black TiO2
更新于2025-09-04 15:30:14
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Pulse duration effect during pulsed gate-bias stress in a-InGaZnO thin film transistors
摘要： We investigated how the zero-voltage duration (0Vd) affects the tendency of degradation during pulsed gate bias stress in a-InGaZnO thin film transistors (TFTs). DC or pulsed negative bias illumination stress (NBIS) or positive bias stress (PBS) was applied to the TFTs for effective stress time of 4,000 s. While pulsed bias stress was being applied, stress-voltage duration (SVd) was set as either 10 s or 1 s per cycle, and 0Vd was varied from 100% to 1% of the SVd. During NBIS, degradation in both threshold voltage and sub-threshold slope became increasingly severe as 0Vd was shortened. However, during pulsed PBS, these trends were almost absent. These different tendencies may occur because the cause of each stress-induced degradation is fundamentally dissimilar; NBIS involves ionization of oxygen vacancies, whereas PBS involves electron trapping. The proposed mechanism was supported by additional bias stress tests on TFTs that had been immersed in H2O, where hydrogen became dominant factor causing the degradation.
关键词： Hydrogen,IGZO,Dynamic stress,Instability,Oxygen vacancy,AC stress
更新于2025-09-04 15:30:14
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Unraveling the oxygen effect on the property of sputtered BaSnO3 thin films
摘要： The perovskite oxide BaSnO3 is a highly topical material for next-generation transparent conducting semiconductors. The foreign chemical doping strategy is largely used to realize the high conductivity in BaSnO3. Removal of oxygen in BaSnO3 is another route to get high conductivity but the oxygen vacancy-property relationships have not been realized completely, which is of fundamental importance for the future optoelectronic applications. Here we report how the oxygen vacancies in sputtered BaSnO3 films can be accounted for the structural and chemical environment, the transport phenomena, and the optoelectronic properties. Oxygen vacancies in BaSnO3 films cause the expansion of the unit cell along the out-of-plane direction, enhance the conductivity, transform the electronic transport mechanism from the thermal activation model to the variable-range hopping (VRH) model, and spawn the sub-band level-assisted photoconduction. The present work further strengthens our understanding of the oxygen effect on the physical properties in BaSnO3-based systems.
关键词： oxygen vacancy,transport property,transparent conductive oxide,BaSnO3,photo response,thin film
更新于2025-09-04 15:30:14
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Correlation between Ni valence and resistance modulation on SmNiO <sub/>3</sub> chemical transistor
摘要： The resistance modulation under various gate voltage (Vg) application conditions was systematically studied for a chemical field effect transistor (FET) composed of a SmNiO3 (SNO) film channel and an ionic liquid gate insulator. The channel resistance of the SNO chemical FET changed nonlinearly over a wide range for different temperatures, Vg magnitudes, and Vg application durations. The correlation between the modulated resistance and the Ni valence state was quantitatively revealed using X-ray photoelectron spectroscopy. A model describing the resistance change with the Vg application conditions was proposed by considering the kinetics of the reduction reaction on the SNO channel. This model enables the resistance to be predicted for given Vg application conditions, and selective resistance modulation over a wide range of resistances has been demonstrated.
关键词： control resistance modulation,nonvolatile,redox reaction,oxygen vacancy,Nickelate thin film
更新于2025-09-04 15:30:14
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Ferroelectric properties of Ag doped PbZr0.53Ti0.47O3 thin film deposited by sol–gel process
摘要： To suppress the generation of oxygen vacancy during the PbZr0.53Ti0.47O3 (PZT) film synthesis process, herein, the 0–3 type Ag/PZT film is chosen as a prototype to systematically investigate the mechanisms of oxygen vacancy decrease and the relationship of ferroelectric properties. The uniform and dense films were successfully fabricated on fluorine tin oxide glasses (FTO) by facile sol–gel processes. It is confirmed the existence of silver nanoparticles in the film, indicating the composite ferroelectric films are of 0–3 type. When Ag doping mole concentration is 0.010 in the sol, a large remnant polarization (Pr) of ~ 50.7 μΧ/cm2 is got, which is 37.9 μΧ/cm2 for pure PZT. UV–vis spectrum confirms the generation of Ag2O in the process of mixing the sol. Furthermore, the oxygen vacancies caused by natural evaporation of lead specie are effectively reduced because of the decomposition of Ag2O, confirmed by X-ray photoelectron spectroscopy. This work points out the generated Ag2O as the intermediate product is the key to achieve high remnant polarization in Ag/PZT based film and make it as a promising candidate for memory applications.
关键词： remnant polarization,oxygen vacancy,Ag doped PbZr0.53Ti0.47O3,sol–gel process,Ferroelectric properties
更新于2025-09-04 15:30:14
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Reversible Control of Physical Properties via an Oxygen-Vacancy-Driven Topotactic Transition in Epitaxial La <sub/>0.7</sub> Sr <sub/>0.3</sub> MnO <sub/>3?</sub><i> <sub/>δ</sub></i> Thin Films
摘要： The vacancy distribution of oxygen and its dynamics directly affect the functional response of complex oxides and their potential applications. Dynamic control of the oxygen composition may provide the possibility to deterministically tune the physical properties and establish a comprehensive understanding of the structure–property relationship in such systems. Here, an oxygen-vacancy-induced topotactic transition from perovskite to brownmillerite and vice versa in epitaxial La0.7Sr0.3MnO3?δ thin films is identified by real-time X-ray diffraction. A novel intermediate phase with a noncentered crystal structure is observed for the first time during the topotactic phase conversion which indicates a distinctive transition route. Polarized neutron reflectometry confirms an oxygen-deficient interfacial layer with drastically reduced nuclear scattering length density, further enabling a quantitative determination of the oxygen stoichiometry (La0.7Sr0.3MnO2.65) for the intermediate state. Associated physical properties of distinct topotactic phases (i.e., ferromagnetic metal and antiferromagnetic insulator) can be reversibly switched by an oxygen desorption/absorption cycling process. Importantly, a significant lowering of necessary conditions (temperatures below 100 °C and conversion time less than 30 min) for the oxygen reloading process is found. These results demonstrate the potential applications of defect engineering in the design of perovskite-based functional materials.
关键词： La0.7Sr0.3MnO3 films,polarized neutron reflectometry,brownmillerite,oxygen vacancy ordering,magnetism
更新于2025-09-04 15:30:14