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The Luminous mechanism of Eu <sup>2+</sup> and Dy <sup>3+</sup> co-doped long persistent luminous fiber
摘要： Fiber-forming polymer polyethylene terephthalate chips were blended with Eu2+ and Dy3+ co-doped SrAl2O4 (SAOED) to afford luminous fiber with long and persistent afterglow. A dynamical model was set up to study the afterglow process in order to correlate the afterglow characteristics with the trap levels of SAOED and luminous fiber. The results indicated that the illustration of initial afterglow for luminous fiber was obviously lower than that of SAOED, but its decay process was moderately slow and therefore longer than that of SAOED. Compared with SAOED, the thermo-luminescence peak of the fiber shifted to the higher temperature, and its intensity was lower than that of SAOED. With the time extension of delay time after excitation, the depth of trap level for luminous fiber in our studies did not show any significant change. The afterglow decay behavior can be best fit by using I ? I0/(1 + bt)2; the fitting showed that the afterglow decay process followed the second order dynamics.
关键词： preparation process,luminous fiber,trap level,mechanism,afterglow
更新于2025-09-04 15:30:14
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Enhanced Temperature Stability and Defect Mechanism of BNT-Based Lead-Free Piezoceramics Investigated by a Quenching Process
摘要： Because of the environmental concerns of eliminating lead from piezoelectric products, bismuth-based perovskite is becoming one of the most potential candidates. However, its relatively low thermal depolarization temperature (Td) is still an imperative obstacle hindering implementation of this material for practical application. Here, an enhanced temperature stability of 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 (BNTBT6) piezoceramics is reported, which can be obtained by the effective quenching process. Quenching process enhances the depolarization temperature to 136 °C, which is 40 °C higher than that of normal sintered samples. By using X-ray photoelectron spectroscopy and electron paramagnetic resonance methods, it is revealed that oxygen vacancy may exist in the quenched samples and consequently pins the domain walls, resulting in significant enhancement of depolarization temperature. Temperature-dependent dielectric, piezoelectric, and ferroelectric behaviors are measured as criteria to evidence the enhanced temperature stability.
关键词： lead-free BNT,quenching,defect mechanism,depolarization temperature
更新于2025-09-04 15:30:14
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Hydrogen Sensing Properties of Co-Doped ZnO Nanoparticles
摘要： In this study, the gas sensing properties of Co-doped ZnO nanoparticles (Co-ZnO NPs) synthesized via a simple sol-gel method are reported. The microstructure and morphology of the synthesized Co-ZnO NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Co-ZnO NPs were then used for developing a conductometric gas sensor for the detection, at mild temperature, of low concentration of hydrogen (H2) in air. To evaluate the selectivity of the sensor, the sensing behavior toward some VOCs such as ethanol and acetone, which represent the most important interferents for breath hydrogen analysis, was also investigated in detail. Results reported demonstrated better selectivity toward hydrogen of the Co-ZnO NPs sensor when compared to pure ZnO. The main factors contributing to this behavior, i.e., the transition from n-type behavior of pristine ZnO to p-type behavior upon Co-doping, the modification of oxygen vacancies and acid-base characteristics have been considered. Hence, this study highlights the importance of Co doping of ZnO to realize a high performance breath hydrogen sensor.
关键词： Co-doped ZnO,gas sensor,sol-gel,nanoparticle,sensing mechanism,hydrogen,ethanol
更新于2025-09-04 15:30:14
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Probing Distinctive Electron Conduction in Multilayer Rhenium Disulfide
摘要： Charge carrier transport in multilayer van der Waals (vdW) materials, which comprise multiple conducting layers, is well described using Thomas–Fermi charge screening (λTF) and interlayer resistance (Rint). When both effects occur in carrier transport, a channel centroid migrates along the c-axis according to a vertical electrostatic force, causing redistribution of the conduction centroid in a multilayer system, unlike a conventional bulk material. Thus far, numerous unique properties of vdW materials are discovered, but direct evidence for distinctive charge transport behavior in 2D layered materials is not demonstrated. Herein, the distinctive electron conduction features are reported in a multilayer rhenium disulfide (ReS2), which provides decoupled vdW interaction between adjacent layers and much high interlayer resistivity in comparison with other transition-metal dichalcogenides materials. The existence of two plateaus in its transconductance curve clearly reveals the relocation of conduction paths with respect to the top and bottom surfaces, which is rationalized by a theoretical resistor network model by accounting of λTF and Rint coupling. The effective tunneling distance probed via low-frequency noise spectroscopy further supports the shift of electron conduction channel along the thickness of ReS2.
关键词： Coulomb screening,charge conduction mechanism,multilayer,transport,anisotropy,rhenium disulfide
更新于2025-09-04 15:30:14
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Synthesis, Characterization and Gas-Sensing Properties of Pristine and SnS2 Functionalized TeO2 Nanowires
摘要： We report the gas-sensing properties of pristine and SnS2 functionalized TeO2 nanowires (NWs). TeO2 NWs were synthesized by a vapor–liquid–solid growth method, and SnS2 functionalization was performed using an atomic layer deposition technique followed by thermal treatment. Structural and morphological analyses verified the formation of pristine and SnS2 functionalized TeO2 NWs with desired composition, phase, and morphology. Interestingly, sensing results showed that the pristine TeO2 NW gas sensor had better sensing properties relative to the SnS2 functionalized TeO2 NW gas sensor. An underlying sensing mechanism is explained in detail, and reasons for the decrease of sensing performance with the SnS2 functionalized TeO2 NW sensor was attributed to the coverage of TeO2 surface by the SnS2 nanoparticles.
关键词： Gas sensor,SnS2,NO2 gas,TeO2,Sensing mechanism
更新于2025-09-04 15:30:14
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Degradation kinetics and mechanism of 3-Chlorobenzoic acid in anoxic water environment using graphene/TiO <sub/>2</sub> as photocatalyst
摘要： Degradation kinetics and mechanism of 3-Chlorobenzoic acid(3-CBA) in anoxic water environment using graphene/TiO2 (GR/TiO2) as photocatalyst had been investigated. The effects of various parameters such as catalyst dosage, pH, initial concentration, catalyst reuse and dissolved oxygen(DO) on 3-CBA photocatalytic degradation kinetics were studied. The qualitative and quantitative analysis for degradation intermediate products and parent compound were studied by using HPLC, HPLC/MS/MS and IC technologies. The results show that the residual concentration of 3-CBA has a good linear relationship and its correlation coefficient R2are all greater than 0.985 by Langmuir-Hinshelwood (L-H) dynamic model under different photocatalytic degradation conditions; Some oxidative degradation products such as 3-chlorophenol, resorcinol, hydroxyquinol are generated, and some reductive degradation products such as 3-chlorobenzaldehyde, 3-hydroxybenzaldehyde, 3-hydroxybenzyl alcohol, cyclohexanediol are produced, and part of 3-CBA are mineralized to generate CO2 when DO is in the range of 0.5~1.0 mg/L; When DO is less than 0.28 mg/L, photocatalytic reduction mainly occurs. The results provide a theoretical basis for photocatalytic in-situ remediation of pollutants in anoxic water environment.
关键词： Degradation kinetics,Degradation mechanism,3-Chlorobenzoic acid,GR/TiO2,Anoxic water environment
更新于2025-09-04 15:30:14
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Facile fabrication of sandwich-like BiOI/AgI/g-C3N4 composites for efficient photocatalytic degradation of methyl orange and reduction of Cr(VI)
摘要： Construction of heterojunction photocatalyst with excellent charge separation has attracted significant attention for solving the global energy crisis and environmental problems. Herein, a series of sandwich-structured BiOI/AgI/g-C3N4 composites were fabricated by a novel and facile method. The AgI was employed as a charge transmission bridge between BiOI and g-C3N4, which could result in more efficient charge transfer and better separation of charge carriers. The results indicated that the BiOI/AgI/g-C3N4 composites exhibited higher photocatalytic activity for the degradation of methyl orange (MO) and reduction of Cr(VI) than that of pure g-C3N4, BiOI, and BiOI/g-C3N4. The amount of AgI had a remarkable influence on the photocatalytic activity of the BiOI/AgI/g-C3N4 composites. Moreover, the BiOI/AgI/g-C3N4 composites exhibited high stability. Finally, a possible reaction mechanism on degradation of MO and reduction of Cr(VI) solutions over the composites was proposed. This work could facilitate a better understanding on the charge transfer process in the composite systems as well as provide a new approach to the rational design of novel advanced materials for practical photocatalytic application.
关键词： Reaction mechanism,Photocatalytic activity,Nanocomposite,BiOI/AgI/g-C3N4
更新于2025-09-04 15:30:14