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Composition Dependence of the Band Gap Energy of the Sb-Rich GaBixSb1?x Alloy (0?≤?x?≤?0.26) Described by the Modified Band Anticrossing Model
摘要： The impurity–host interaction and the impurity–impurity interaction exist in the Sb-rich GaBixSb1?x alloy. It is found that the effect of impurity–impurity on the band gap energy can be neglected. The impurity–host interaction not only depends on the Bi content, but also on the content of the host material. In order to describe the band gap energy of the Sb-rich GaBixSb1?x, the virtual crystal approximation for conduction band minimum (CBM) and the modified valence band anticrossing model for valence band maximum (VBM) are applied. It is also found that when the Bi content is about 0.259, the band gap energy of GaBixSb1?x becomes 0 eV. In addition, it is found that the U CBM depending on Bi content is much stronger than that of the U VBM. It is relative to two factors. One is that the conduction band offset between GaSb and GaBi is much larger than the valence band offset. The other is that the energy difference between the Bi level and the U VBM of GaSb is very large. The large energy difference usually leads to a weak coupling interaction between the Bi level and the U VBM of GaSb, thus resulting in weak composition dependence of the U VBM in the Sb-rich range.
关键词： Bi level,band gap energy,Sb-rich,GaBixSb1?x
更新于2025-09-23 15:23:52
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One-step preparation of Bi4O5BrxI2?x solid solution with superior photocatalytic performance for organic pollutants degradation under visible light
摘要： Highly e?cient photocatalyst is the demand for controlling environmental pollution, especially the toxic and refractory organic contaminants. Herein, a series of bismuth-rich Bi4O5BrxI2?x solid solution photocatalysts were prepared through a one-step solvothermal method by adjusting the molar ratio of Br/I, which can e?ectively degrade organic pollutants of phenol and Rhodamine B (RhB). The structure and morphology of the photocatalysts were characterized by X-ray di?raction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM). The results indicated that Bi4O5BrxI2?x solid solution photocatalysts were successfully synthesized. The obtained samples showed superior photocatalytic activities toward phenol and RhB under visible light irradiation. Besides, the photocatalytic performances can be optimized by changing the ratio of Br/I. When the ratio of Br/I was 1:1, the obtained Bi4O5BrxI2?x solid solution exhibited the highest photocatalytic performance, which was nearly 6.4 and 8.5 times higher than that of pure Bi4O5Br2 and Bi4O5I2 for phenol degradation, respectively. The enhancement can be ascribed to the high e?cient separation of photogenerated electron-hole pairs in Bi4O5BrxI2?x solid solution, which was con?rmed by the corresponding optical and photoelectrochemical characterizations.
关键词： One-step synthesis,Photocatalytic,Bi4O5BrxI2?x solid solution,Bismuth-rich
更新于2025-09-23 15:23:52
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Modified dielectric and ferroelectric properties in the composite of ferrimagnetic Co1.75Fe1.25O4 ferrite and ferroelectric BaTiO3 perovskite in comparison to Co1.75Fe1.25O4 ferrite
摘要： The ferrimagnetic Co1.75Fe1.25O4 ferrite with cubic spinel structure (space group Fd3m) was made into composite by mixing with ferroelectric BaTiO3 perovskite with tetragonal structure (space group P4mm) at the mass ratio 50:50. Disc shaped composite powder was finally heated at 1000 °C to study the structure, dielectric and ferroelectric properties. The electrical conductivity, dielectric response and ferroelectric properties of the composite samples are remarkably modified in comparison to their ferrite counterparts before making the composite. The composite system has shown improvement of dielectric constant with reduced dielectric loss factor and electrical conductivity in comparison to the ferrite samples. The mechanism of modified dielectric properties was understood by analyzing ac conductivity data using Jonscher's power law, complex impedance spectra in Cole-Cole plots using equivalent circuit model, and complex electrical modulus spectra using Kohlrausch, Williams and Watts (KWW) proposed model. Electrical conductivity in the composite material was determined by small polaron hoping (SPH) up to measurement temperature 400 K (close to ferroelectric transition of BaTiO3) and overlapping large polaron hopping conductivity at higher temperatures. In contrast, SPH dominates throughout the measurement temperature range for ferrite samples. The space charge polarization, which was largely effective at low frequencies and high measurement temperatures, is significantly reduced in composite samples. High capacitive response in composite samples and its extension up to high measurement temperature is confirmed from the temperature dependence of phase shift and well defined ferroelectric polarization loop and associated electrical parameters.
关键词： Composite dielectric,Polaron hopping,Ferroelectric polarization,Co rich spinel oxide
更新于2025-09-23 15:23:52
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Facile strategy for controllable synthesis of hierarchical hollow MoS2 microspheres with enhanced photocatalytic properties
摘要： Tailored design of photocatalysts with complicated hollow structures is of great importance for promoting environmental remediation. In this paper, monodispersed hierarchical hollow MoS2 microspheres have been prepared via a facile and economical hydrothermal method with the assistance of surfactant (polyethylene-polypropylene glycol (F68)). The unusual design displays three important features: large specific surface area, strong light absorption, and rich catalytic active sites. The specific surface area of the hierarchical hollow MoS2 microspheres is 21.75 m2g-1, which is higher than that of MoS2 particles (4.05 m2g-1) and commercial MoS2 (2.84 m2g-1). Meanwhile, the hierarchical hollow MoS2 microspheres possess strong light absorption around a broadband wavelength from 200 nm to 800 nm. Furthermore, the ordered MoS2 nanosheets which assemble to the outer surface of the hierarchical hollow MoS2 microspheres display rich catalytic active sites, which are beneficial in promoting the fast transport of charge carriers during the process of photocatalytic reaction. As a result, the photodegradation activity test demonstrates that the hierarchical hollow MoS2 microspheres exhibit excellent photocatalytic activity and recycling stability. The reaction rate constant of the hierarchical hollow MoS2 microspheres for the photodegradation of RhB is 25.32 and 18.18 times faster than that of MoS2 particles and commercial MoS2, respectively.
关键词： Unusual design,Photocatalysts,MoS2,Rich catalytic sites,Large surface area,Broadband absorption
更新于2025-09-23 15:23:52
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Structural, electrical, optical and thermoelectric properties of e-beam evaporated Bi-rich Bi2Te3 thin films
摘要： Bi-rich Bi2Te3 thin films are prepared at 300 K using e-beam evaporation technique. A source power of 45 W for e-beam was used. Post deposition, these as-deposited Bi-rich Bi2Te3 (Bi-BT-AD) films are annealed at 100 °C (Bi-BT-100), 200 °C (Bi-BT-200) and 300 °C (Bi-BT-300) for 1 h under a pressure of 3 × 10-4 Pa. X-ray diffraction measurements reveal the presence of Bi phase together with crystalline Bi2Te3 indicating the possible presence of Bi-rich Bi2Te3 phase in the Bi-BT-AD film. The broad peaks from Bi2Te3 (015) plane indicates nanocrystalline nature of particles. With annealing, no change in diffraction pattern is observed for Bi-BT-100. However, Bi-BT-200 and Bi-BT-300 films show the emergence of x-ray reflection from unknown phases around 2θ ~ 20° and 47°. This indicates Bi related secondary phase segregation and the thermodynamic instability for the presence of Bi in Bi2Te3 lattice. From Raman studies it is discerned that Bi secondary phase coexist along with the Bi-rich Bi2Te3 nanocrystalline grains. On vacuum annealing Bi-rich Bi2Te3 thin films prevails as evidenced from the p-type electrical characteristics, while excess Bi disappears and converts into an unknown minor phase. The resistivity of all the annealed films are ~ 0.9 × 10-4 Ωcm. The Seebeck coefficients also do not show any change and remain around 33 to 36 μV/K. Thermoelectric properties of Bi-BT-100 exhibit high power factors when measured at different ΔT with a maximum of ~ 17.5 × 10-4 W/K2m for ΔT=100 °C. Thus, unlike the near-stoichiometric thin films, Bi-rich thin films require low temperature annealing (~100 °C) to achieve optimized parameters. Bi-rich Bi2Te3 thin films also show higher power factor compared to the near-stoichiometric thin films. Thus, favourable thermoelectric properties can be achieved at 300 K for temperature sensitive device fabrication using Bi-rich Bi2Te3 thin films.
关键词： Bismuth-rich bismuth telluride,thin films,electron-beam evaporation,power factor.
更新于2025-09-23 15:23:52
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Influence of Platelet Aggregate Formation in Blood Samples on Light Transmission Aggregometry Results
摘要： Background: Light transmission aggregometry is a standard method used to evaluate platelet function. However, in clinical settings, light transmission aggregometry results sometimes fail to reflect actual platelet hyperactivity. In patients with suspected platelet hyperactivity such as thrombosis, platelet aggregates are frequently detected in citrated blood samples using a scattergram of a hematology analyzer. This study aimed to evaluate the effects of platelet aggregate formation on light transmission aggregometry results. Methods: We used 19 citrated blood samples in which platelet aggregate formation was intentionally induced by a hematology analysis process. Employing fully automated light transmission aggregometry and agonists including adenosine diphosphate or collagen, light transmission aggregometry maximum aggregation percentage, platelet count, and mean platelet volume of platelet-rich plasma before and after platelet aggregate formation were evaluated. Results: Light transmission aggregometry maximum aggregation percentage with adenosine diphosphate or collagen was significantly lower in the samples after than before platelet aggregate formation. Platelet count and mean platelet volume were both decreased by platelet aggregate formation (P < .01), suggesting that maximum aggregation percentage reduction was caused by the decrease in activated large platelets in the platelet-rich plasma. Conclusion: This study clarified that platelet aggregate formation in blood samples interfered with an accurate assessment of platelet hyperactivity. To ensure reliability of light transmission aggregometry results, we must confirm that platelet aggregates have not formed in the sample, especially in those of patients with platelet hyperactivity.
关键词： platelet count,hematology analyzer,light transmission aggregometry,mean platelet volume,platelet-rich plasma,Platelet aggregate
更新于2025-09-23 15:22:29
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Electrochemical and Structural Investigation on Ultrathin ALD ZnO and TiO <sub/>2</sub> Coated Lithium-Rich Layered Oxide Cathodes
摘要： Ultrathin coatings (1.5 ± 0.3 nm) of titanium dioxide and zinc oxide were deposited on lithium-rich layered oxide cathodes (Li1.2Mn0.6Ni0.2O2, LLO) by atomic layer deposition (ALD). The structures, electrochemical performances, and thermal stabilities of these coatings were investigated. An ultrathin uniform coating was obtained for TiO2 but not for ZnO because of di?erences in the layer growth mechanism. Regarding the initial charge?discharge curves under a current density of 0.04 C rate, the TiO2 coated samples exhibited a higher discharge capacity, 242 mAhg?1, compared with the ZnO coated samples, 220 mAhg?1, or the pristine samples, 228 mAhg?1. Both coated samples exhibited more stable cycling performance and thermal stability than the pristine samples. After 80 cycles under 0.5 C rate, the TiO2 and ZnO coated samples were found to have higher capacity retention (～94% and 78%, respectively) than the pristine samples (68%). The reaction temperature of the exothermic peak of the TiO2 and ZnO coated samples at 4.8 V shifted to 280 °C with heat release of 88.7 J/g for TiO2 and 270 °C with heat release of 154.6 J/g for ZnO. This is compared with an exothermic peak at 258 °C with heat release of 253.5 J/g for the pristine sample. In particular, an enhanced rate capability was only observed for the TiO2 coated samples. When the current densities were higher than 2 C rate, the TiO2 coated samples exhibited superior capacities than the pristine and ZnO coated samples. At a current density of 5 and 10 C rate, the capacities were found to be 120 and 95 mAhg?1. The improved electrochemical performances were mainly attributed to lower resistance ?lm. This feature lead to more preactivation of the charge transfer, which resulted from the layer morphology of the TiO2 LLO, smoother electron transport, and suppression of more side reactions, when compared with the island structure of the ZnO ?lm.
关键词： ZnO,Cathode,Atomic layer deposition,Lithium-rich layered oxides,TiO2,Lithium ion battery
更新于2025-09-23 15:21:21
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Ordered Mesoporous C?N? with a Combined Triazole and Triazine Framework and Its Graphene Hybrids
摘要： Mesoporous carbon nitrides (MCN) with C3N4 stoichiometry could find applications in fields ranging from catalysis, sensing, and adsorption–separation to biotechnology. The extension of the synthesis of MCN with different nitrogen contents and chemical structures promises access to even a wide range of applications. Here we show mesoporous C3N5 with a combined triazole and triazine framework prepared via a simple self-assembly of 5-amino-1H-tetrazole (5-ATTZ). We are able to hybridize these nanostructures with graphene by using graphene–mesoporous silica hybrids as a template to tune the electronic properties. Density functional theory calculations in combination with various spectroscopic analyses clearly demonstrate that the C3N5 consists of 1 triazole and 2 triazine moieties. The triazole-based mesoporous C3N5 and its graphene hybrids are found to be highly active for oxygen reduction reaction (ORR) with a higher diffusion-limiting current density and a decreased overpotential than those of bulk g-C3N4. We expect that this simple approach to the triazole-based mesoporous C3N5 could be extended for the preparation of series of new class of MCN nanostructures and their hybrids.
关键词： oxygen reduction reaction,porous materials,electrocatalysts,N-rich carbon nitrides,structure
更新于2025-09-23 15:21:21
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Optimization of synthesis condition of water-resistant and thin titanium oxide layer-coated Ni-rich layered cathode materials and their cathode performance
摘要： In this study, in order to develop water-resistant LiNiaCobAl1?a?bO2 (a > 0.85, NCA) cathode materials which exhibit high-rate performance, the surface coating of NCA with titanium oxide (TiOx) was examined. The synthesis conditions for the TiOx-coated NCA cathode materials were investigated, by taking into account some essential factors in the surface coating of NCA by TiOx, with a view to improving the rate performance. We successfully prepared the TiOx-coated NCA cathode material, the rate performance of which is superior to that of the conventionally prepared NCA cathode materials, typically using a polyvinylidene difluoride (PVdF) binder and N-methyl-2-pyrrolidone (NMP) solvent. Their surface analysis suggested that the specific surface structure of TiOx layer coated on the NCA particle leads to both a water-resistant property and a high permeability of Li+ ions through it in the charging/discharging process.
关键词： Lithium ion secondary battery,Water-based hybrid polymer binder,TiOx coating layer,Water resistance,Ni-rich lithium transition metal oxide
更新于2025-09-23 15:21:21
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A Polyallylamine Anchored Aminea??Rich Lasera??Ablated Graphene Platform for Facile and Highly Selective Electrochemical IgG Biomarker Detection
摘要： Current immunosensors have an insufficient number of binding sites for the recognition of biomolecules, which leads to false positive or negative results. In this research, a facile, cost-effective, disposable, and highly selective electrochemical immunosensing platform is developed based on cationic polyelectrolyte polyallylamine (PAAMI) anchored laser-ablated graphene (LAG). Here, for the first time, PAAMI is introduced to stabilize LAG flakes, while retaining the intrinsic thermal and electronic properties of the substrate by noncovalent π–π interaction and electrostatic physical absorption. The sensing platform offers a suitable number of anchoring sites for the immobilized antibodies by providing NH2 functional groups. The proper grafting of PAAMI is confirmed through X-ray photoelectron spectroscopy and Raman spectroscopy. The immunosensing platform is applied to detect immunoglobulin (IgG) biomarkers as a proof of concept. Under optimized conditions, the sensing platform exhibits a linear range of 0.012–15 and 15–352 ng mL?1 with a limit of detection of 6 pg mL?1 for IgG detection with high selectivity. Based on the analysis, the developed immunosensing platform can be used for point-of-care detection of IgG in clinical diagnostic centers. Furthermore, the developed strategy is well suited for the detection of other cancer biomarkers after immobilizing the relevant antibodies.
关键词： IgG detection,electrochemical immunosensors,NH2-rich graphene,polyallylamine,laser-ablated graphene
更新于2025-09-23 15:19:57