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Morphology control and luminescence properties of red-emitting BaSiF6:Eu3+ hexagonal nanorod phosphors for WLEDs
摘要： To promote the development of solid-state lighting industry, exploring excellent inorganic phosphors has been always a scientific and applied hot issue. Herein, a series of efficient red BaSiF6:Eu3+ hexagonal nanorod phosphors with varied size and morphology were successfully prepared through a hydrothermal route. The reaction time, dosage of surfactant and solvent play an important role in the formation of the nanorod structures. The corresponding formation mechanism was discussed and revealed. The effects of surfactant, reaction time and solvent on photoluminescence properties of the as-prepared BaSiF6:Eu3+ nanorod phosphors were investigated in detail. Under excitation at 394 nm, all samples emit bright red light due to the typical Eu3+ 4f-4f transitions. Comparing the luminescence intensity of samples with different size of nanorods, it is found that the length of the nanorod is about 10–20 μm, the luminescence intensity of the sample is 3–5 times of the initial intensity of the nanorod sample that the length is around 30–40 μm. Moreover, when adding ethylene glycol as a solvent, the luminescence intensity of samples with different morphology increases with the increase of the reaction time. Importantly, as the temperature rising to 150 °C, the integrated intensity of the as-prepared sample still could obtain more than 95% of the intensity at room temperature, indicating the phosphors show excellent thermal stability. Thus, the as-prepared BaSiF6:Eu3+ nanorod phosphor is a potential red-emitting phosphor for white light-emitting diodes (WLEDs).
关键词： BaSiF6:Eu3+,luminescence properties,hydrothermal synthesis,thermal stability,WLEDs,hexagonal nanorod phosphors
更新于2025-09-23 15:19:57
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Superficial preparation of biocompatible carbon quantum dots for antimicrobial applications
摘要： Orange waste peel CQDs has been synthesized via simple hydrothermal method. The UV–visible spectrum shows near band edge absorbance and optical energy bandgap has been calculated as 3.44 eV and 5.60 eV. In addition, the antibacterial assay of CQDs was carried out against two kind of bacteria such as gram positive and gram-negative bacteria. It has been noted that the CQDs show good antibacterial activity towards the gram-negative bacterium Pseudomonas aeruginosa (ZOI: 30 mm). Antibacterial activity of natural waste CQDs was compared with chemically synthesized NPs and QDs.
关键词： Tauc’s plot,CQDs,Hydrothermal method,Electron microscopy,Antibacterial assay
更新于2025-09-23 15:19:57
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Formation of carbon quantum dots and graphene nanosheets from different abundant carbonaceous materials
摘要： Carbon quantum dots (CQDs) and graphene nanosheets (GNs) are one of the most attractive fluorescent carbon nano-sized materials with unique features of optical and physico-chemical properties having various applications in chemical sensing, biomedicine, semiconductor devices, photo-catalyzing, and electrocatalysis. The primary purpose of this preliminary work is the feasibility study for synthesis of nano-structured value-added carbon products i.e., CQDs and GNs from cheap and abundant carbon sources, such as coal, petroleum coke, graphite, and coal-based humic acid by hydrothermal techniques. The physico-chemical properties of the raw precursors were evaluated by proximate and ultimate analysis. High resolution-transmission electron microscopy (HR-TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared (FT-IR) spectroscopy, X-ray powder diffractometer (XRD), UV-visible (UV-vis), and fluorescence (FL) spectrophotometer were used to achieve physico-chemical parameters of carbon nanostructures, to better comprehend the development of carbon quantum dots and graphene nanosheets. HR-TEM analysis indicates that the dimensions of the synthesized CQDs from different carbon sources exist in the range of 3-6.5 nm. The approximate quantum yields (QY) of the synthesized carbon nanomaterials were found to be about 2-22%. The synthesised carbon based nanomaterials (i.e. CQDs and GNs) have been efficiently used in the photo-degradation of harmful 2-nitrophenols (2-NP) with the efficiency of 80.79% for CQDs and 82.53% for GNs, respectively. The present study provides a simple and environmentally-sound technique for large-scale fabrication of typical CQDs and GNs from abundantly available low-grade coal and other carbonaceous materials for photo-catalysis application.
关键词： Carbon Dots,Photocatalytic degradation,Carbonaceous materials,Graphene nanosheet,Hydrothermal treatment,Fluorescent materials
更新于2025-09-23 15:19:57
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Blue luminescence carbon quantum dots derived from oil palm empty fruit bunch biomass
摘要： Carbon quantum dots (CQDs) have attracted tremendous attention for their interesting properties such as excellent chemical and photo stability, good water dispersibility, biocompatibility and possessing outstanding photoluminescence (PL) properties. In this study, oil palm biomass is used as the carbon precursor to produce CQDs and exhibit high luminescent properties. However, a large amount of biomass produces by the oil palm industry is either burnt in the open air or disposed in waste ponds and contributes to global climate change via emissions of carbon dioxide and methane. Hence, synthesis the CQDs from oil palm biomass by hydrothermal treatment method has formed excellent properties in optical properties that could be comparable to semiconductor quantum dots. The results have shown the diameter size of CQDs in the range of 2-5 nm. While, the optical properties, UV-vis spectrum of CQDs have given a strong absorption at 282 nm and obtains in brown color under visible light and emitting blue luminescence under 365 nm of UV lamp. Furthermore, PL spectra of CQDs have shown excitation and emission wavelength at 360 nm and 450 nm, respectively. This is attribute to the excitation-wavelength dependent of PL properties. Hence, the spectra from FTIR showed the existence of hydroxyl and carboxyl groups on the CQDs would have originated from lignocellulosic materials, thus resulted in excellent water stability and solubility properties of CQDs. The presented study is the green approached reprocessed biomass from waste to materials with excellent optical properties that could utilize in various field of applications.
关键词： hydrothermal treatment,photoluminescence,optical properties,Carbon quantum dots,oil palm biomass
更新于2025-09-23 15:19:57
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Novel hydrothermal route for synthesis of photoactive Cu2ZnSn(S,Se)4 nanocrystalline thin film: efficient photovoltaic performance
摘要： This work reports single-step deposition of Cu2ZnSn(S,Se)4 (CZTSSe) nanocrystalline film via simple and non-toxic hydrothermal route. The hydrothermal growth of CZTSSe multinary nanocrystalline film formation based on Ostwald ripening law which results in highly oriented nanocrystalline nanoflakes. The UV–Vis spectroscopy illustrates that maximum absorption was observed in the range of 650–700 nm with band gap energy of 1.48 eV. Structural studies confirm the formation of pure-phase kesterite crystal structure. Further, Raman shift at 174 cm?1, 196 cm?1 and 236 cm?1 shows A1 mode of vibration corresponding to kesterite structure. Densely packed and compact nanoflake formation was observed in SEM studies. Compositional analysis confirms the stoichiometric film formation with expected valence states of CZTSSe stoichiometry: Cu+, Zn2+, Sn4+, S2? and Se2?. The photoelectrochemical cell performance of CZTSSe film photoelectrode was investigated using simple two-electrode system. In dark condition, J–V measurement demonstrates semiconductor behavior and under illumination shows generation of photocurrent of 3.64 mA/cm2 at a photovoltage of 400 mV. The CZTSSe films show photoconversion efficiency (η) of 3.41%, indicating that the hydrothermally grown CZTSSe photocathode is a promising material for film solar cell technology. Electron impedance spectroscopy illustrated generation of charge transport resistance of 465 Ω.
关键词： Hydrothermal route,Photovoltaic performance,Cu2ZnSn(S,Nanocrystalline film,Se)4
更新于2025-09-23 15:19:57
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[IEEE 2018 International Semiconductor Conference (CAS) - Sinaia, Romania (2018.10.10-2018.10.12)] 2018 International Semiconductor Conference (CAS) - Substrate Effect on the Morphology and Optical Properties of ZnO Nanorods Layers Grown by Microwave-Assisted Hydrothermal Method
摘要： The substrate effect on the morphology and optical properties of zinc oxide nanorods synthesized by microwave-assisted hydrothermal method have been investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-VIS-NIR optical absorption and reflecting spectroscopy. The band gap energy of the investigated samples was calculated from absorbance spectra in the (200-1100) nm wavelengths range.
关键词： optical properties,ZnO nanorods,band gap energy,microwave-assisted hydrothermal synthesis,morphology
更新于2025-09-23 15:19:57
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Response surface optimization of hydrothermal synthesis of Bismuth ferrite nanoparticles under supercritical water conditions: Application for photocatalytic degradation of Tetracycline
摘要： Ultra?ne bismuth ferrite (BiFeO3) powders have been successfully synthesized through supercritical water hydrothermal technique, in a batch type reactor. A Box–Behnken three-level experimental design was used to optimize the process variables a?ecting the BiFeO3 e?ciency includes pH of starting solution (1.5–12.5), reaction time (1–2 h), and reaction temperature (450–550 ℃). The samples were characterized via X–ray powder di?raction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The model was validated by analysis of variance (ANOVA) and conducting an experiment at optimal design conditions (temperature of 522 ℃, pH of 3.25 and 1.3 h). The maximum BiFeO3 production e?ciency which obtained at optimum condition was about 45%. The attained results showed good correlation between the predicted model and experimental data (Model P-Value = 0.0052). The present work con?rmed that the supercritical water hydrothermal method is a suitable way to produce BiFeO3 nanoparticles with a mean grain size of 60 nm and narrow size distribution. Moreover, the optical property of the product was investigated by Ultraviolet-visible di?use re?ectance spectroscopy (DRS). The attained nanostructures showed a narrow band gap of 1.96 eV, indicating that BiFeO3 powders can be applied as a novel visible-light-responsive photocatalyst for degradation of tetracycline (TC). Photocatalytic experiments revealed that using BiFeO3 nanoparticles, TC degradation e?ciency of 80.3% and 87.5% could be reached under UV and visible light radiations, respectively. Furthermore, it was found the degradation of TC follows the pseudo-second-order kinetics by BiFeO3.
关键词： Tetracycline,Bismuth ferrite nanoparticles,Photocatalyst,Supercritical water,Hydrothermal synthesis
更新于2025-09-23 15:19:57
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The Effect of Calcination Temperature Variation on the Sensitivity of CO Gas Sensor from Zinc Oxide Material by Hydrothermal Process
摘要： Carbon monoxide (CO) is a poisonous gas and could be lethal towards human. A sensitive CO gas sensor is necessary to prevent accidents caused by CO gas. ZnO is a semiconductor material having many applications including gas sensors. However ZnO is rarely reported to be used as CO gas sensor material. Therefore, in this research, CO gas sensor has been prepared from ZnO material synthesized via hydrothermal process at 100°C for 24 hours using ZnCl2 powder and NH4OH solution. The resulted ZnO gel was subsequently dried and spin-coated on a glass substrate. The ZnO-coated glasses were then calcined at various temperatures of 500°C, 550°C, and 600°C for 30 minutes. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Brunauer-Emmet-Teller (BET) analysis were used to characterized the morphology, structure and active surface area of ZnO. The sensitivity of the ZnO material towards CO gas was measured using a potentiostat in a chamber with operating temperatures 30°C, 50°C, and 100°C with each of gas concentration 10 ppm, 100 ppm, 250 ppm, and 500 ppm. It was found that the sample calcined at 550oC showed the highest sensitivity towards CO gas (0.82) due to the highest active surface area (47.2 m2g-1). It was also observed that the sensitivity increased with the increasing of operating temperature and CO gas concentration.
关键词： ZnO,sensitivity,CO gas,hydrothermal
更新于2025-09-23 15:19:57
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One-step hydrothermal growth and electrochromic properties of highly stable Prussian green film and device
摘要： We have demonstrated that Prussian green (PG) ?lm can be directly grown on ?uorine-doped tin oxides (FTO) glass by a facile, template-free and one-step hydrothermal process, and a reaction mechanism for the formation of PG ?lm under the hydrothermal conditions is also proposed. The as-grown PG ?lm exhibits a much better cycling stability than PG ?lm prepared by electrochemical method. The electrochromic device based on the as-grown PG ?lm shows reversible and multi-stage color changes among green, blue and colorless states. Large optical modulations of 58% and 42% between colorless and both blue and green state, respectively, fast switching times of 1.1 and 2.4 s and a high coloration e?ciency of 79.1 cm2 C?1 are also achieved for the PG device, making it promising candidates for applications in high-performance smart windows and displays.
关键词： Prussian green,Electrochromic,Hydrothermal
更新于2025-09-23 15:19:57
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Effect of seed layer on growth of rutile TiO <sub/>2</sub> nanorods
摘要： For achieving the high quality of titanium dioxide (TiO2) nanorods, herein, we present a synthesis of rutile TiO2 nanorods on a transparent conductive fluorine-doped tin oxide (FTO) glass substratewith seed layer by a two-step method. TiO2 thin films were first precoated by spin coating and annealing, followed by the growth of TiO2 nanorods with a hydrothermal method. The crystallographic nanostructures and properties of the nanorods were investigated. XRD results demonstrate that seed layer was tetragonal anatase TiO2 structure while nanorods had tetragonal rutile TiO2 structure. Since the hydrothermal technique was conducted in medium acid, structure of nanorods was induced to form in rutile phase. The major characteristic orientation of nanorods on the seed layers was (002) and minor in (101) planes. FE-SEM results show that seed layer enhances the process to achieve vertical-aligned orientation of the TiO2 nanorods, which contribute to develop electron transport rate and could pay an important role inelectron transport layer in high-performance Perovskite solar cell.
关键词： seed layer,hydrothermal method,rutile TiO2 nanorods,Perovskite solar cell,electron transport layer
更新于2025-09-23 15:19:57