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Effect of K2O addition on glass structure, complex impedance and energy storage density of NaNbO3 based glass-ceramics
摘要： (40-x)Na2O-xK2O-40Nb2O5-20SiO2 (x=0, 5, 10, 15mol%) glass-ceramics are synthesized by traditional melts method. The glass-ceramics are tested by X-ray diffraction (XRD) techniques, and NaNbO3 as major phase led a high permittivity. A microstructure with nanoscale grains enclosed by glass phase is observed by scanning electron microscope (SEM). With the increase of content of K2O, a relaxed glass network structure is obtained, and more kinds of phase are formed. Permittivity comes to 174 approximately when x=5mol%. In addition, the activation energy (Ea) of residual glass phase for Na2O-K2O-Nb2O5-SiO2 glass-ceramics firstly increase then decrease. Breakdown strength (BDS) of all samples increase and then decrease with the increase of content of K2O, and maximum BDS is obtained when x=10mol%. And maximum theoretical energy density is 1.43J/cm3 when x=5mol%.
关键词： breakdown strength,glass network structure,Na2O-K2O-Nb2O5-SiO2 glass-ceramics
更新于2025-11-14 17:28:48
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Ethanol sensing properties and reduced sensor resistance using porous Nb2O5-TiO2 n-n junction nanofibers
摘要： One-dimensional (1D) and porous Nb2O5-TiO2 n-n junction nanofibers with different Nb molar ratios have been synthesized by a simple electrospinning approach. A decrease in the average grain size and consequently an increase in the specific surface area were observed due to the introduction of Nb2O5 into TiO2 nanofibers. In comparison with pure TiO2 nanofibers, the Nb2O5-TiO2 nanofibers exhibited improved ethanol sensing response and a reduction in electrical resistance. The optimum operation temperature was reduced from 300 °C for pure TiO2 to 250 °C for Nb2O5-TiO2. The best sensing property was found for Nb2O5-TiO2 with 6 mol% Nb2O5, showing the highest response of 21.64–500 ppm ethanol at 250 °C, which was 2.79 times as high as that of pure TiO2 nanofibers at 300 °C. The reduction of Nb2O5-TiO2 based sensor resistance was attributed to the substitution of Ti4+ by Nb5+ ions and the formation of n-n junctions between Nb2O5 nanoparticles and TiO2 nanoparticles. The enhancement sensing mechanism of Nb2O5-TiO2 nanofibers was mainly ascribed to the enhanced resistance modulation owing to the substitution of Ti4+ by Nb5+ ions, formation of n-n junctions, and high surface area as well as small grain size of Nb2O5-TiO2 nanofibers.
关键词： Gas sensor,n-n junctions,Electrospinning,Nb2O5,TiO2
更新于2025-11-14 17:15:25
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[IEEE 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - Kuala Lumpur (2018.8.15-2018.8.17)] 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - Engineering the Properties of Nb<inf>2</inf>O<inf>5</inf>-ZnO Nanostructures via Dual Synthesis Techniques
摘要： In this paper, dual techniques; anodization and hydrothermal, were introduced to synthesize the Nb2O5-ZnO nanostructures. The purpose of this research is to engineer the properties of the Nb2O5-ZnO nanostructures which can offer new optical and electrical behaviors and also lead to large surface area. Synthesis of Nb2O5 has been conducted by anodizing the Niobium foil in the electrolyte containing NH4F and ethylene glycol. Meanwhile, ZnO was hydrothermalized with Zinc Nitrate precursor solution for 18 hr at different temperatures. All samples were characterized using FESEM, XRD and UV-Vis absorbance spectra. The morphological and properties changes of the Nb2O5-ZnO nanostructures are systematically investigated as a function of hydrothermal temperature.
关键词： ZnO,dual synthesis,anodization,Nb2O5,nanostructure,hydrothermal
更新于2025-09-23 15:21:21
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Preparation and Thickness Optimization of TiO 2 /Nb 2 O 5 Photoanode for Dye Sensitized Solar Cells
摘要： In recent years, dye-sensitized solar cells (DSSCs) have received much attention as an alternative to silicon-based solar cells due to their various advantages. It is one of the possible options for large-scale roll-to-roll production of photovoltaic cells, on flexible plastic or glass substrates. Nonetheless, due to technical constraints, the maximum efficiency is only half the efficiency of conventional solar cells. Therefore improving the efficiency of DSSC technology is critical for widespread adoption. This work will attempt to summarize the influence of adding mesoporous Nb2O5 nanoparticle in different percentage of weight to TiO2 photoanode. Prepared TiO2/Nb2O5 nanocomposites are characterized using UV-Vis absorption spectroscopy, XRD and FESEM. DSSCs are fabricated and studied for their photovoltaic performance under the illumination of simulated sunlight of 100mWcm-2. Adding Nb2O5 nanoparticles has resulted in an increase of short-circuit current density (Jsc) and efficiency (η) significantly. Also, an attempt has been made to optimize the film thickness by studying efficiency as a function of film thickness. The cell with 24μm thick electrode emerges as an optimized cell with remarkable performance.
关键词： desorption,TiO2/Nb2O5,DSSCs,thickness optimization,TiO2
更新于2025-09-12 10:27:22
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Enhanced performance of carbon-based planar CsPbBr3 perovskite solar cells with room-temperature sputtered Nb2O5 electron transport layer
摘要： Inorganic CsPbBr3 perovskite solar cell (PSC) has attracted much attention owing to its outstanding air and thermal stability and low cost manufacture process. Crystalline TiO2 (c-TiO2) has been widely used as electron-transporting layer (ETL) material for inorganic CsPbBr3 PSC. However, c-TiO2 requires high-temperature (> 450 °C) fabrication process which impedes the application of flexible inorganic CsPbBr3 PSC and its low electron mobility further limits the performance enhancement. Herein, we prepared novel amorphous Nb2O5 (a-Nb2O5) ETL through a facile room-temperature sputtering method for inorganic planar CsPbBr3 PSC. The PSC with a-Nb2O5 ETL has gained a champion efficiency of 5.74%, which is higher than that of the PSC (5.12% or 4.67%) based on crystalline Nb2O5 (c-Nb2O5) ETL or c-TiO2 ETL by high-temperature (500 °C) annealing. The improved photovoltaic characteristic for CsPbBr3 PSC with a-Nb2O5 ETL may be ascribed to its suitable work function, high optical transmittance, low charge recombination at the a-Nb2O5/CsPbBr3 interface and the superior crystallinity of CsPbBr3 film deposited on a-Nb2O5 ETL. Moreover, the a-Nb2O5-based CsPbBr3 PSC without encapsulation exhibits a good long-term stability in ambient atmosphere. This work offers a new research direction for preparing high-performance inorganic PSC.
关键词： Amorphous Nb2O5,Planar structure,Inorganic perovskite solar cells,Electron-transporting layer
更新于2025-09-11 14:15:04
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Preparation of Nb2O5-decorated hierarchical porous ZnO microspheres with enhanced photocatalytic degradation of palm oil mill effluent
摘要： In the present work, Nb2O5-decorated hierarchical porous ZnO microspheres (ZnO/Nb2O5) were successfully prepared through a facile surfactant-free method. The as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy and Brunauer–Emmett–Teller surface area analyses. Under UV light irradiation, the ZnO/Nb2O5 composites degraded palm oil mill effluent (POME) efficiently and demonstrated much higher photocatalytic activity compared to those of pure ZnO and Nb2O5. The enhanced photocatalytic degradation performance of ZnO/Nb2O5 composites was attributed to the high charge separation efficiency and hydroxyl radical generation ability as verified by the photoluminescence spectra. Phytotoxicity test upon the POME degradation over ZnO/Nb2O5 photocatalysis considerably decreased through the measurement of radicle lengths of Vigna radiata. Moreover, the ZnO/Nb2O5 composites were reused several times without appreciable loss of activity. This work revealed that the as-prepared ZnO/Nb2O5 composites have great potential for practical applications in the field of wastewater treatment.
关键词： Nb2O5-decorated hierarchical porous ZnO microspheres,Photocatalytic degradation,Charge separation efficiency,Palm oil mill effluent,Hydroxyl radical generation
更新于2025-09-10 09:29:36
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Micro/nanoscale mesoporous Nb2O5 particles: Effect of synthesis conditions and doping with N, C, or S on their properties
摘要： A simple methodology was designed to obtain mesoporous niobium pentoxide (Nb2O5) solids functionalized with nitrogen, carbon, or sulfur. Dopant precursors were urea (N), citric acid (C) and thiourea (S). The doped solids were characterized using IR, Raman and diffuse reflectance UV–Vis spectroscopies, powder X-ray diffraction, adsorption–desorption isotherms, transmission electron and scanning electron microscopies. Depending on the amount of surfactant (cetyltrimethyl ammonium bromide — CTAB) used during synthesis, the solid presented mainly an orthorhombic crystal structure or an amorphous phase (for the sample with 0.25 mol/L CTAB). The adsorption–desorption isotherms of the synthesized solids showed hysteresis loops ( H1 andH4 types) characteristic of mesoporous solids, while transmission electron micrographs showed a disordered structure of pore channels known as ‘‘wormholes’’. There was considerable interaction between the dopant anion (mainly N and S) and the solid surface, generating new surface chemical species that clogged the pores, reducing specific surface and pore volume. The doped mesoporous Nb2O5 materials were polycrystalline, formed by primary monocrystalline particles of nanometric size (10–20 nm). Doping with N, C and S caused an important effect on the absorption of visible light, reducing the band gap energy value to 2.95 eV when doped with N, and to ～2.8 eV with S, relative to that of the undoped sample (3.03 eV). This result is important considering the potential use of mesoporous Nb2O5 materials in photocatalytic processes.
关键词： N, C and S dopants,Synthesis,Nanomaterials,Characterization,Mesoporous Nb2O5
更新于2025-09-10 09:29:36
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Influence of Ba/Ti ratio on PTCR effect of Bam(Ti1?xNbx)O <sub/>3</sub> ceramics prepared by the reduction sintering-reoxidation method
摘要： In this work, we investigate the influences of Ba/Ti ratio and sintering conditions on the characteristics of positive temperature coefficient of resistance (PTCR) and electrical properties of Bam(Ti1?xNbx)O3 (BTN) ceramics. The ceramics were fired at 1190?C for 0.5–6.0 h in a reducing atmosphere and then reoxidized at 600–650?C for 0–8 h. The Ba/Ti ratio (m) affected the electrical properties and PTCR effect of the BTN specimens. The room-temperature (RT) resistance of the BTN samples initially decreased (0.994 < m < 1.006) and then increased (1.006 < m < 1.018) as the Ba/Ti ratio increased. Moreover, BTN ceramics exhibit a pronounced PTCR effect, with a resistance jump greater by 3.0 orders of magnitude and a low 0.1 ? RT resistance at a low reoxidation temperature of 600?C after sintering under a reducing atmosphere. Furthermore, the average sample grain size increased along with the Ba/Ti ratio. In addition, the influence of the sintering time and the reoxidation time on the electrical properties and the PTCR effect were also investigated.
关键词： PTC effect,Nb2O5-dopant,Ba/Ti ratio,BaTiO3
更新于2025-09-09 09:28:46
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Graphitic Carbon Nitride Impregnated Niobium Oxide (g-C <sub/>3</sub> N <sub/>4</sub> /Nb <sub/>2</sub> O <sub/>5</sub> ) Type (II) Heterojunctions and Its Synergetic Solar-Driven Hydrogen Generation
摘要： Graphitic carbon nitride (g-C3N4) based catalysts are evolving in energy harvesting applications due to their robustness, nontoxicity, and most important photocatalytic efficiencies. In this work, we successfully engineered g-C3N4/Nb2O5 type (II) heterojunction via pulse sonochemical technique based on opposite charge-induced hetero-aggregation on the surface. The agglomerated spherical Nb2O5 nanoparticles (NPs) having diameter 30-40 nm observed on the lamellar surface of g-C3N4 in FESEM images. The XRD and XPS analysis confirm the orthorhombic phase and formation of the g-C3N4/Nb2O5 heterostructure. The FTIR spectra of g-C3N4/Nb2O5 show characteristic poly s-triazine bands from 1250 to 1650 cm-1. Moreover, g-C3N4/Nb2O5 exhibited the lower bandgap value of 2.82 eV as compared to Nb2O5 (3.25eV) with significant redshift and enhance visible light absorption. The Mott-Schottky (MS) analysis confirms the formation of heterojunction between g-C3N4 and Nb2O5, with significant band shifting towards lower hydrogen evolution reaction (HER) potential. The g-C3N4/Nb2O5 heterojunctions showed many folds enhanced photocurrent response from photoelectrochemical (PEC) water splitting, and the value reached to – 0.17 mA/cm2 with good stability and insignificant dark photocurrent at 1.0 V vs RHE. The electrochemical impedance spectroscopic (EIS) measurements further elucidate the suppression of photogenerated electrons/holes as the radius of the semicircle significantly decreased in case of heterojunction formation. The enhanced photocatalytic hydrogen generation by the heterostructures could be attributed to the effective formation of heterojunctions between the g-C3N4 and Nb2O5 semiconductors, causing the migration of the photogenerated electrons and holes, hence increasing their lifetimes.
关键词： Pulse Sonication,PEC Water Splitting,g-C3N4,Photocurrent density,Nb2O5 NPs
更新于2025-09-09 09:28:46