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Soluble and insoluble polymer-inorganic systems based on poly(methyl methacrylate), modified with ZrO2-LnO1.5 (Ln = Eu, Tb) nanoparticles: Comparison of their photoluminescence
摘要： The study of the lanthanide ion luminescence as a function of their environment in polymer-inorganic composites is necessary for better understanding of the electron energy transfer processes in a condensed state. From a practical point of view, these materials are promising for optics and medicine. The nanoparticles of ZrO2-LnO1.5 (Ln = Eu, Tb) solid solutions were synthesized by hydrothermal method. The surface functionalization of the obtained nanoparticles by vinyl groups was carried out using 3-(trimethoxysilyl)propyl methacrylate. Soluble and cross-linked composites based on poly(methyl methacrylate) with ZrO2-LnO1.5 nanoparticles were synthesized using radical polymerization in solution and bulk. Molecular weight, thermal stability, and microhardness of the obtained composite materials were determined. The influence of both the polymerization conditions and the forming composite structure on the lanthanide ion photoluminescence in ZrO2 nanoparticles covalently bonded to the polymer matrix was studied. The combination of ZrO2-EuO1.5 and ZrO2-TbO1.5 nanoparticles in the poly(methyl methacrylate) resulted in the production of composites with photoluminescence spectra overlapping the red and green regions of the visible range. It was shown that the structure of the composite affects the absorbing capacity of luminescent centers and allows shifting the excitation spectrum in the longer wavelength region.
关键词： hydrothermal synthesis,poly(methyl methacrylate),rare-earth ions,solid solutions,zirconia,hybrid nanomaterials
更新于2025-09-23 15:21:21
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A hydrothermally synthesized MoS <sub/>2(1a??x)</sub> Se <sub/>2x</sub> alloy with deep-shallow level conversion for enhanced performance of photodetectors
摘要： Photoelectric detectors based on binary transition metal chalcogenides have attracted widespread attention in recent years. However, due to the high-temperature synthesis of binary TMD, high-density deep-level defect states may be generated, leading to poor responsiveness or a long response time. Besides, the addition of an alloy will change the DLDSs from deep to shallow energy levels caused by S vacancies. In this paper, MoS2(1?x)Se2x nanostructures were synthesized by a hydrothermal method, and a novel type of photodetector was fabricated by using the synthesized material as a light sensitive material. The MoSSe-based photodetector not only has a high photocurrent, but also exhibits a wide spectral response in the range of 405 nm to 808 nm. At the same time, it can achieve a responsivity of 1.753 mA W?1 under 660 nm laser irradiation of 1.75 mW mm?2. Therefore, this work can be considered as a method of constructing a new type of photodetector with a simple process and low cost.
关键词： MoS2(1?x)Se2x,photoelectric detectors,photodetector,transition metal chalcogenides,hydrothermal synthesis
更新于2025-09-23 15:21:01
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{0 0 1}-Facet-Exposed Ag <sub/>4</sub> V <sub/>2</sub> O <sub/>7</sub> Nanoplates: Additive-Free Hydrothermal Synthesis and Enhanced Photocatalytic Activity
摘要： The synthesis of silver pyrovanadate, Ag4V2O7, nanoplates with exposed {0 0 1}-facets by a facile, additive-free hydrothermal method was described in this paper. The photocatalytic activity of rhodamine B over Ag4V2O7 samples under solar light irradiation was also evaluated. By using an equimolar mixture of NH4VO3 and AgNO3 with the presence of a suitable amount of ammonia, Ag4V2O7 nanoplates were obtained readily and purely at temperatures from 100 to 140°C for 4 h. The c-axis orientation growth of Ag4V2O7 nanoplates occurred and increased monotonously with temperatures in the range of over 100 up to 140°C. Further increase in hydrothermal temperature up to 220°C, the Ag4V2O7 phase no longer existed and the β-AgVO3 phase was formed instead. The photocatalytic activity of the optimized Ag4V2O7 sample comprising {0 0 1}-facet-exposed nanoplates with the highest degree of orientation was significantly higher than that of the random-oriented sample. The effects of using ammonia as a complexing agent on the structure, microstructure, texture, exposed facet, and photocatalytic activity of Ag4V2O7 samples were also investigated for the first time.
关键词： photocatalytic activity,hydrothermal synthesis,Ag4V2O7,rhodamine B,nanoplates,solar light irradiation
更新于2025-09-23 15:21:01
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A Facile Microwave-Assisted Hydrothermal Synthesis of Graphene Quantum Dots for Organic Solar Cell Efficiency Improvement
摘要： Carbon-based nanomaterials have successively remained at the forefront of different research fields and applications for years. Understanding of low-dimension carbon material family (CNT, fullerenes, graphene, and graphene quantum dots) has arrived at a certain extension. In this report, graphene quantum dots were synthesized from graphene oxide with a microwave-assisted hydrothermal method. Compared with conventional time-consuming hydrothermal routes, this novel method requires a much shorter time, around ten minutes. Successful formation of quantum dots derived from graphene sheets was verified with microscopic and spectroscopic characterization. Nanoparticles present a diameter of about 2-8 nm, blue emission under ultraviolet excitation, and good dispersion in polar solvents and can be collected in powder form. The synthesized graphene quantum dots were utilized as a hole transport layer in organic solar cells to enhance the cell quantum efficiency. Such quantum dots possess energy levels (Ec and Ev) relevant to HOMO and LUMO levels of conductive polymers. Mixing P3HT:PCBM polymer and graphene quantum dots of sufficient extent notably helps reduce potential difference at interfaces of the two materials. Overall efficiency consequently advances to 1.43%, an increase of more than 44% compared with pristine cells (0.99%).
关键词： microwave-assisted hydrothermal synthesis,organic solar cells,graphene quantum dots,efficiency improvement
更新于2025-09-23 15:19:57
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Controlled synthesis of ultrathin MoS <sub/>2</sub> nanoflowers for highly enhanced NO <sub/>2</sub> sensing at room temperature
摘要： Fabrication of a high-performance room-temperature (RT) gas sensor is important for the future integration of sensors into smart, portable and Internet-of-Things (IoT)-based devices. Herein, we developed a NO2 gas sensor based on ultrathin MoS2 nanoflowers with high sensitivity at RT. The MoS2 flower-like nanostructures were synthesised via a simple hydrothermal method with different growth times of 24, 36, 48, and 60 h. The synthesised MoS2 nanoflowers were subsequently characterised by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy. The petal-like nanosheets in pure MoS2 agglomerated to form a flower-like structure with Raman vibrational modes at 378 and 403 cm?1 and crystallisation in the hexagonal phase. The specific surface areas of the MoS2 grown at different times were measured by using the Brunauer–Emmett–Teller method. The largest specific surface area of 56.57 m2 g?1 was obtained for the MoS2 nanoflowers grown for 48 h. This sample also possessed the smallest activation energy of 0.08 eV. The gas-sensing characteristics of sensors based on the synthesised MoS2 nanostructures were investigated using oxidising and reducing gases, such as NO2, SO2, H2, CH4, CO and NH3, at different concentrations and at working temperatures ranging from RT to 150 °C. The sensor based on the MoS2 nanoflowers grown for 48 h showed a high gas response of 67.4% and high selectivity to 10 ppm NO2 at RT. This finding can be ascribed to the synergistic effects of largest specific surface area, smallest crystallite size and lowest activation energy of the MoS2-48 h sample among the samples. The sensors also exhibited a relative humidity-independent sensing characteristic at RT and a low detection limit of 84 ppb, thereby allowing their practical application to portable IoT-based devices.
关键词： gas sensing,room temperature,hydrothermal synthesis,MoS2 nanoflowers,NO2 gas sensor
更新于2025-09-23 15:19:57
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Controlled synthesis and upconversion luminescence properties of Yb3+/Er3+ co-doped Bi2O3 nanospheres for optical and X-ray computed tomography imaging
摘要： Bi2O3 nanospheres co-doped with Yb3t/Er3t upconverting ions pair have been successfully synthesized via a facile hydrothermal method followed by a heat treatment. The resulting Bi2O3:Yb3t,Er3t nanospheres show a monodisperse spherical morphology with narrow size distribution (~180 nm) and display intense upconversion luminescence under 980 nm laser excitation. It is found that the crystal structure, morphology and upconversion luminescence properties of nanospheres have a direct relationship with the doping concentration of Yb3t and the subsequent calcination temperature. These Bi2O3:Yb3t,Er3t nanospheres can be prepared in large quantities and can be easily modified with a layer of biocompatible polyethyleneimine (PEI) molecules. The yielded nanospheres could not only maintain uniform size and morphological characteristics, but also show good water dispersibility and biocompatibility. Remarkably, these Bi2O3:Yb3t,Er3t upconversion nanophosphors could also act as an effective contrast agent for X-ray computed tomography (CT) imaging, which show higher contrast efficacy than commercial iodine-based contrast agent. The proposed facile synthetic route and inexpensive matrix materials pave the way for broad use of these Bi2O3:Yb3t,Er3t nanospheres as ideal dual-mode bio-imaging probes in biomedical field.
关键词： Hydrothermal synthesis,CT imaging,Bi2O3,Upconversion luminescence,Nanophosphors
更新于2025-09-23 15:19:57
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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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[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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Synthesis of highly crystalline photocatalysts based on TiO2 and ZnO for the degradation of organic impurities under visible-light irradiation
摘要： A TiO2–ZnO binary oxide system (with molar ratio TiO2:ZnO = 8:2) was synthesized by a hydrothermal method, assisted by calcination at temperatures of 500, 600 and 700 °C, using zinc citrate as the precursor of ZnO. The morphology (SEM, TEM), crystalline structure (XRD, Raman spectroscopy), diffuse reflectance spectra (DRS), chemical surface composition (EDXRF), porous structure parameters (low-temperature N2 sorption) and characteristic functional groups (FT-IR) of the TiO2–ZnO oxide materials were comprehensively analyzed. The novelty of this work is the observation of the coexistence of the crystalline structures of anatase and ZnTiO3 in TiO2–ZnO oxide materials. Moreover, it is shown that the obtained materials absorb visible radiation. The key stage of the study was the evaluation of the photocatalytic activity of the TiO2–ZnO binary oxide systems in the degradation of model organic pollutants: C.I. Basic Red 1, C.I. Basic Violet 10, C.I. Basic Blue 3 and 4-nitrophenol. For all synthesized materials, a high efficiency of degradation of the model organic impurities was demonstrated. The results show that the synthesized products may be materials of interest for use in the degradation of organic pollutants. Moreover, the kinetics of the photocatalytic degradation of selected organic compounds were determined based on the Langmuir–Hinshelwood equation, assuming a pseudo-first-order (PFO) reaction.
关键词： Titania,Zinc oxide,Photocatalysis,Binary oxide systems,Hydrothermal synthesis
更新于2025-09-19 17:15:36