Core–shell nanoparticles by silica coating of metal oxides in a dual-stage hydrothermal flow reactor

2016 ◽  
Vol 52 (16) ◽  
pp. 3434-3437 ◽  
Author(s):  
H. L. Hellstern ◽  
A. Mamakhel ◽  
M. Bremholm ◽  
B. B. Iversen
Keyword(s):  
Continuous Flow ◽  
Flow Reactor ◽  
Synthesis Method ◽  
Silica Coating ◽  
Core Shell ◽  
Narrow Size Distribution ◽  
Shell Nanoparticles ◽  
Coated Nanoparticles ◽  
Dual Stage ◽  
Core Shell Nanoparticles

A green, fast, high-throughput, continuous-flow hydrothermal synthesis method is explored for preparation of silica coated nanoparticles with narrow size distribution.

Iron-Carbon Core-Shell Nanoparticles Obtained with Different Conditions of Synthesis

2017 ◽  
Vol 899 ◽  
pp. 221-226 ◽  
Author(s):  
M.M. Lima ◽  
J.P.Z. Gonçalves ◽  
C. Soares ◽  
Humberto Gracher Riella ◽  
S.C. Fernandes ◽  
...  
Keyword(s):  
Synthesis Method ◽  
Processing Parameters ◽  
Effect Of Temperature ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Shell Mass ◽  
The Core ◽  
Iron Precursor ◽  
Co Precipitation ◽  
Core Shell Nanoparticles

Core–shell Fe2O3@C nanoparticles are very studied due to its biocompatibility with plant and animals cells and due its special properties of chemical adsorption. Thus, the definition of an easy synthesis method of these nanoparticles is very important to the scientific studies and to future applications of these materials. For example, the properties of these nanoparticles depend of the combination between some processing parameters, as the temperature, time, chemical composition, atmosphere and others. The mass yield of the synthesis processes depend of these parameters and are important information. In this work the effect of temperature and of the concentration of the iron precursor were evaluated on the characteristics of the proposed nanoparticles. The nanostructures of Fe2O3 coated with carbon (Fe2O3@C) were synthetized by adapted co-precipitation hydrothermal rote. In 40.0 ml of distilled water was added 1.800 g of glucose, 6.006 g of urea, 0.500 g of polyethylene Glycol (PEG 1500) and different concentrations of iron nitrate Fe (NO2)3.9H2O and different temperature values were applied. The Fe2O3@C core-shell were characterized by scanning electron microscopy (SEM/FEG), Energy Dispersive Scanning (EDS) and X-ray Diffractions (XRD). Results showed that nanoparticles form clusters with different sizes that are dependent on the temperature values and Fe (NO3)3.9H2O concentration. The core-shell mass has a linear relation with the iron precursor mass and the reaction temperatures influences the microstructure of the core-shell nanoparticles.

scholarly journals Characterization of multifunctional β-NaEuF4/NaGdF4 core–shell nanoparticles with narrow size distribution

Nanoscale ◽  
2016 ◽  
Vol 8 (5) ◽  
pp. 2832-2843 ◽  
Author(s):  
Lilli Schneider ◽  
Thorben Rinkel ◽  
Benjamin Voß ◽  
Artur Chrobak ◽  
Johann P. Klare ◽  
...  
Keyword(s):  
Size Distribution ◽  
Core Shell ◽  
Narrow Size Distribution ◽  
Shell Nanoparticles ◽  
Core Shell Nanoparticles

We characterized NaEuF4/NaGdF4 core–shell nanoparticles.

scholarly journals Au nanobipyramids@mSiO2 core–shell nanoparticles for plasmon-enhanced singlet oxygen photooxygenations in segmented flow microreactors

2020 ◽  
Vol 2 (11) ◽  
pp. 5280-5287
Author(s):  
Carlos Mendoza ◽  
Anthony Désert ◽  
Denis Chateau ◽  
Cyrille Monnereau ◽  
Lhoussain Khrouz ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Continuous Flow ◽  
Core Shell ◽  
Segmented Flow ◽  
Shell Nanoparticles ◽  
Gold Nanobipyramids ◽  
Core Shell Nanoparticles ◽  
Flow Microreactors

Gold nanobipyramids coated with 12 nm mSiO2 shells exhibited metal-enhanced 1O2 generation in continuous-flow photooxygenation reactions.

Synthesis and Characterization of Co3O4-MnxCo3-xO4 Core-Shell Nanoparticles

MRS Advances ◽  
2018 ◽  
Vol 3 (47-48) ◽  
pp. 2899-2904
Author(s):  
Ning Bian ◽  
Robert A. Mayanovic ◽  
Mourad Benamara
Keyword(s):  
Electron Microscopy ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Blocking Temperature ◽  
Core Shell ◽  
Average Particle ◽  
Shell Nanoparticles ◽  
X Ray ◽  
The Core ◽  
Core Shell Nanoparticles

ABSTRACTThe mixed-valence oxide Co3O4 nanoparticles, having the normal spinel structure, possess large surface area, active-site surface adsorption properties, and fast ion diffusivities. Consequently, they are widely used in lithium-ion batteries, as well as for gas sensing and heterogeneous catalysis applications. In our research, we use a two-step method to synthesize Co3O4–based core-shell nanoparticles (CSNs). Cobalt oxide (Co3O4) nanoparticles were successfully synthesized using a wet synthesis method employing KOH and cobalt acetate. Manganese was incorporated into the Co3O4 structure to synthesize inverted Co3O4@MnxCo3-xO4 CSNs using a hydrothermal method. By adjustment of pH value, we obtained two different morphologies of CSNs, one resulting in pseudo-spherical and octahedron-shaped nanoparticles (PS type) whereas the second type predominantly have a nanoplate (NP type) morphology. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS) have been performed in order to determine the morphological and structural properties of our CSNs, whereas the magnetic properties have been characterized using a superconducting quantum interference device (SQUID) magnetometer. XRD and TEM results show that the CSNs have the same spinel crystal structure throughout the core and shell with an average particle size of ∼19.8 nm. Our Co3O4 nanoparticles, as measured prior to CSN formation, are shown to be antiferromagnetic (AFM) in nature as shown by the magnetization data. Our SQUID data indicate that the core-shell nanoparticles have both AFM (due to the Co3O4 core) and ferrimagnetic properties (of the shell) with a coercivity field of 300 Oe and 150 Oe at 5 K for the PS and NP samples, respectively. The magnetization vs temperature data show a spin order-disorder transition at ∼33 K and a superparamagnetic blocking temperature of ∼90 K for both batches.

scholarly journals Pd@Zn core–shell nanoparticles of controllable shell thickness for catalytic methanol production

2016 ◽  
Vol 6 (21) ◽  
pp. 7698-7702 ◽  
Author(s):  
Fenglin Liao ◽  
Xin-Ping Wu ◽  
Jianwei Zheng ◽  
Meng-Jung Li ◽  
Ziyan Zeng ◽  
...  
Keyword(s):  
Shell Thickness ◽  
Synthesis Method ◽  
Catalytic Performance ◽  
Shell Structures ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Methanol Production ◽  
Novel Synthesis ◽  
Core Shell Nanoparticles

A novel synthesis method of nano-Pd@Zn core–shell structures with controllable shell thickness showing remarkable catalytic performance in CO2hydrogenation.

Critical shell thickness and emission enhancement of NaYF4:Yb,Er/NaYF4/silica core/shell/shell nanoparticles

2009 ◽  
Vol 24 (12) ◽  
pp. 3559-3568 ◽  
Author(s):  
Li Peng Qian ◽  
Du Yuan ◽  
Guang Shun Yi ◽  
Gan Moog Chow
Keyword(s):  
Emission Intensity ◽  
Shell Thickness ◽  
Silica Coating ◽  
Inorganic Nanoparticles ◽  
Upconversion Nanoparticles ◽  
Core Shell ◽  
Fluorescent Nanoparticles ◽  
Shell Nanoparticles ◽  
Silica Core ◽  
Core Shell Nanoparticles

Amorphous silica shells, used for functionalization of inorganic nanoparticles in bioapplications, were coated on chemically synthesized NaYF4:Yb,Er upconversion fluorescent nanoparticles via a reverse microemulsion method by using dual surfactants of polyoxyethylene (5) nonylphenylether and 1-hexanol, and tetraethyl orthosilicate as precursor. NaYF4:Yb,Er nanoparticles were equiaxed with a particle size of 11.1 ± 1.3 nm. The thickness of silica shell was ∼8 nm. NaYF4:Yb,Er/silica core/shell nanoparticles were well dispersed in solvents such as ethanol and deionized water. The emission intensities of NaYF4:Yb,Er/silica core/shell nanoparticles remained the same as that of uncoated nanoparticles after surface functionalization with an amine group using (3-aminopropyl)-trimethoxysilan. Silica, although providing a good barrier to the nonradiative relaxation between the upconversion nanoparticles and the environments, did not enhance the emission intensity of upconversion nanoparticles. To increase the emission intensity of NaYF4:Yb,Er/silica core/shell nanoparticles, an undoped NaYF4 shell (∼3-nm thick) was deposited on the upconversion nanoparticles before the silica coating. The total emission intensity of NaYF4:Yb,Er/NaYF4/silica core/shell/shell nanoparticles increased by 15 times compared to that without the intermediate NaYF4 shell. The critical shell thickness of NaYF4 was ∼3 nm, beyond which no further emission intensity enhancement was observed.

scholarly journals Enhanced Energy-Transfer Properties in Core-Shell Photoluminescent Nanoparticles Using Mesoporous SiO2 Intermediate Layers

2020 ◽  
Vol 58 (2) ◽  
pp. 137-144
Author(s):  
Woo Hyeong Sim ◽  
Seyun Kim ◽  
Weon Ho Shin ◽  
Hyung Mo Jeong
Keyword(s):  
Optical Properties ◽  
Energy Transfer ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
Infrared Light ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Intermediate Layers ◽  
Core Shell Nanoparticles

Multi-layer core-shell nanoparticles (YVO<sub>4</sub>:Nd<sup>3+</sup>/mSiO<sub>2</sub>/SiO<sub>2</sub>) consisting of silica cores (SiO<sub>2</sub>), mesoporous silica (mSiO<sub>2</sub>) intermediate layers, and Neodymium doped rare-earth phosphor (YVO<sub>4</sub>:Nd<sup>3+</sup>) shell layers were successfully synthesized using the stepwise sol-gel method. The morphological structure and optical properties of the functional core-shell nanoparticles were characterized and evaluated by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) analysis. mSiO<sub>2</sub> intermediate layers were utilized as the bridge between the core and shell materials. Their porous surfaces served to anchor the YVO<sub>4</sub>:Nd<sup>3+</sup> crystals. This prevents energy loss during the energy transfer of electrons, resulting in improved optical properties. The use of intermediate layer combinations of mSiO<sub>2</sub>/SiO<sub>2</sub> in the coreshell structure also improved cost-effectiveness, because the core is filled with cheap silica, not expensive phosphors. Even though the nanoparticles used only a thin layer of the photoluminescent shell materials, the optical properties, resulting from the energy-transfer emitting mid-infrared light, were remarkably enhanced by increasing the crystallinity of the phosphor. To demonstrate the practical use of the synthesis method, the photoluminescent properties of the core-shell nanoparticles were optimized by adjusting the annealing temperature and scaling to mass production. We believe that our efficient synthetic strategy provides a facile way of obtaining functional, cost-effective core-shell nanoparticles with improved photoluminescent properties.

scholarly journals Iron Oxide–Silica Core–Shell Nanoparticles Functionalized with Essential Oils for Antimicrobial Therapies

Antibiotics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1138
Author(s):  
Cristina Chircov ◽  
Maria-Florentina Matei ◽  
Ionela Andreea Neacșu ◽  
Bogdan Stefan Vasile ◽  
Ovidiu-Cristian Oprea ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Essential Oils ◽  
Synthesis Method ◽  
Gas Chromatography Mass Spectrometry ◽  
In Vitro Tests ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Nanostructured Systems ◽  
Core Shell Nanoparticles ◽  
The Impact

Recent years have witnessed a tremendous interest in the use of essential oils in biomedical applications due to their intrinsic antimicrobial, antioxidant, and anticancer properties. However, their low aqueous solubility and high volatility compromise their maximum potential, thus requiring the development of efficient supports for their delivery. Hence, this manuscript focuses on developing nanostructured systems based on Fe3O4@SiO2 core–shell nanoparticles and three different types of essential oils, i.e., thyme, rosemary, and basil, to overcome these limitations. Specifically, this work represents a comparative study between co-precipitation and microwave-assisted hydrothermal methods for the synthesis of Fe3O4@SiO2 core–shell nanoparticles. All magnetic samples were characterized by X-ray diffraction (XRD), gas chromatography-mass spectrometry (GC-MS), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry and differential scanning calorimetry (TG-DSC), and vibrating sample magnetometry (VSM) to study the impact of the synthesis method on the nanoparticle formation and properties, in terms of crystallinity, purity, size, morphology, stability, and magnetization. Moreover, the antimicrobial properties of the synthesized nanocomposites were assessed through in vitro tests on Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. In this manner, this study demonstrated the efficiency of the core–shell nanostructured systems as potential applications in antimicrobial therapies.

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