scholarly journals Synthesis and Characterization of Core–Shell Magnetic Nanoparticles NiFe2O4@Au

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1075
Author(s):  
Diana Saykova ◽  
Svetlana Saikova ◽  
Yuri Mikhlin ◽  
Marina Panteleeva ◽  
Ruslan Ivantsov ◽  
...  
Keyword(s):  
Nickel Ferrite ◽  
Gold Deposition ◽  
Core Shell ◽  
X Ray ◽  
Gold Shell ◽  
Thick Gold ◽  
Synthesis Strategy ◽  
Vis Spectroscopy ◽  
Shell Particles ◽  
Average Size

In this study, NiFe2O4@Au core–shell nanoparticles were prepared by the direct reduction of gold on the magnetic surface using amino acid methionine as a reducer and a stabilizing agent simultaneously. The obtained nanoparticles after three steps of gold deposition had an average size of about 120 nm. The analysis of particles was performed by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis spectroscopy techniques. The results indicate successful synthesis of core–shell particles with the magnetic core, which consists of a few agglomerated nickel ferrite crystals with an average size 25.2 ± 2.0 nm, and the thick gold shell consists of fused Au0 nanoparticles (NPs). Magnetic properties of the obtained nanoparticles were examined with magnetic circular dichroism. It was shown that the magnetic behavior of NiFe2O4@Au NPs is typical for superparamagnetic NPs and corresponds to that for NiFe2O4 NPs without a gold shell. The results indicate the successful synthesis of core–shell particles with the magnetic nickel ferrite core and thick gold shell, and open the potential for the application of the investigated hybrid nanoparticles in hyperthermia, targeted drug delivery, magnetic resonance imaging, or cell separation. The developed synthesis strategy can be extended to other metal ferrites and iron oxides.

Monodisperse Fe3O4/Fe Core/Shell Nanoparticles with Enhanced Magnetic Property

2011 ◽  
Vol 306-307 ◽  
pp. 410-415
Author(s):  
Li Sun ◽  
Fu Tian Liu ◽  
Qi Hui Jiang ◽  
Xiu Xiu Chen ◽  
Ping Yang
Keyword(s):  
Average Diameter ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Shell Nanoparticles ◽  
X Ray ◽  
Transmission Electron ◽  
Shell Particles ◽  
Core Shell Nanoparticles

Core/shell type nanoparticles with an average diameter of 20nm were synthesized by chemical precipitation method. Firstly, Monodisperse Fe3O4 nanoparticles were synthesized by solvethermal method. FeSO4ž7H2O and NaBH4 were respectively dissolved in distilled water, then moderated Fe3O4 particles and surfactant(PVP) were ultrasonic dispersed into the FeSO4ž7H2O solution. The resulting solution was stirred 2 h at room temperature. Fe could be deposited on the surface of monodispersed Fe3O4 nanoparticles to form core-shell particles. The particles were characterized by using various experimental techniques, such as transmission electron microscopy (TEM), X-ray diffraction (XRD), AGM and DTA. The results suggest that the saturation magnetization of the nanocomposites is 100 emu/g. The composition of the samples show monodisperse and the sides of the core/shell nanoparticles are 20-30nm. It is noted that the formation of Fe3O4/Fe nanocomposites magnetite nanoparticles possess superparamagnetic property.

scholarly journals Green Synthesis and Catalytic Activity of Silver Nanoparticles Based on Piper chaba Stem Extracts

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1777 ◽  
Author(s):  
Md. Mahiuddin ◽  
Prianka Saha ◽  
Bungo Ochiai
Keyword(s):  
Electron Microscopy ◽  
Silver Nanoparticles ◽  
Green Synthesis ◽  
Ftir Spectroscopy ◽  
Visual Observation ◽  
Face Centered Cubic ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Face Centered ◽  
Average Size

A green synthesis of silver nanoparticles (AgNPs) was conducted using the stem extract of Piper chaba, which is a plant abundantly growing in South and Southeast Asia. The synthesis was carried out at different reaction conditions, i.e., reaction temperature, concentrations of the extract and silver nitrate, reaction time, and pH. The synthesized AgNPs were characterized by visual observation, ultraviolet–visible (UV-vis) spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), energy dispersive x-ray (EDX), and Fourier transform infrared (FTIR) spectroscopy. The characterization results revealed that AgNPs were uniformly dispersed and exhibited a moderate size distribution. They were mostly spherical crystals with face-centered cubic structures and an average size of 19 nm. The FTIR spectroscopy and DLS analysis indicated that the phytochemicals capping the surface of AgNPs stabilize the dispersion through anionic repulsion. The synthesized AgNPs effectively catalyzed the reduction of 4-nitrophenol (4-NP) and degradation of methylene blue (MB) in the presence of sodium borohydride.

scholarly journals CO Preferential Photo-Oxidation in Excess of Hydrogen in Dark and Simulated Solar Light Irradiation over AuCu-Based Catalysts on SBA-15 Mesoporous Silica-Titania

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1203 ◽  
Author(s):  
Isabel Barroso-Martín ◽  
Antonia Infantes-Molina ◽  
Aldo Talon ◽  
Loretta Storaro ◽  
Elena Rodríguez-Aguado ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Light Irradiation ◽  
Solar Light ◽  
X Ray ◽  
Preferential Oxidation Of Co ◽  
Simulated Solar Light ◽  
Solar Light Irradiation ◽  
Vis Spectroscopy ◽  
Average Size ◽  
Adsorption Desorption

In this work, SBA-15 silica and silica-titania have been used as supports for photocatalysts based on AuCu alloy (Au:Cu = 1) to be used in the preferential oxidation of CO (CO-PROX) in excess of hydrogen at room temperature and atmospheric pressure both in the dark and under simulated solar light irradiation. To study their textural, structural, chemical and optical properties, the samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), adsorption-desorption of N2 at −196 °C, 13C and 29Si solid state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance ultraviolet-visible (DRUV-vis) spectroscopy. Titanium was present mainly in the form of titania aggregates, but also as small particles interacting with the SBA support. In both catalysts, the metal alloy nanoparticles displayed an average size of 4 nm as demonstrated by TEM measurements. AuCu/Ti-SBA turned out to be photoactive and selective in the photo-CO-PROX reaction showing the highest activity, with conversion and selectivity towards CO2 of 80%, due both to the presence of titania incorporated in SBA-15 and to the synergistic effect of Cu when alloyed with Au.

Synthesis and Characterization of SiO2@Y2MoO6:Eu3+ Core–Shell Structured Spherical Phosphors by Sol–Gel Process

2016 ◽  
Vol 16 (4) ◽  
pp. 3914-3920 ◽  
Author(s):  
G. Z Li ◽  
F. H Liu ◽  
Z. S Chu ◽  
D. M Wu ◽  
L. B Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Annealing Temperature ◽  
Uv Light ◽  
Sol Gel ◽  
Spherical Shape ◽  
Core Shell ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Average Size

SiO2@Y2MoO6:Eu3+ core–shell phosphors were prepared by the sol–gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO2@Y2MoO6:Eu3+ core–shell phosphors. The XRD results demonstrated that the Y2MoO6:Eu3+ layers on the SiO2 spheres crystallized after being annealed at 700 °C and the crystallinity increased with raising the annealing temperature. The obtained core–shell phosphors have spherical shape with narrow size distribution (average size ca. 640 nm), non-agglomeration, and smooth surface. The thickness of the Y2MoO6:Eu3+ shells on the SiO2 cores could be easily tailored by varying the number of deposition cycles (70 nm for four deposition cycles). The Eu3+ shows a strong PL emission (dominated by 5D0–7F2 red emission at 614 nm) under the excitation of 347 nm UV light. The PL intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles.

scholarly journals Green Synthesis and Characterization of Gold Nanoparticles using Ethanolic Turmeric Crude Extract At Neutral Ph

2020 ◽  
Vol 8 (6) ◽  
pp. 1535-1539
Keyword(s):  
Gold Nanoparticles ◽  
Crude Extract ◽  
Fourier Transforms ◽  
Cost Effective ◽  
Green Method ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Effective Synthesis ◽  
Average Size

There is a great interest in the development of green protocols to avoid environmental and health hazards. In this research, the eco-friendly and cost-effective synthesis of gold nanoparticles (GNPs) has been achieved by the green method using ethanolic turmeric crude extract at pH 7. The bioac-tive compounds of turmeric crude extract are responsible for the reduction, capping and sta-bility of the GNPs. The characterization of GNPs was carried out by ultraviolet-visible (UV-vis) spectroscopy, Fourier transforms infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy. The UV-vis spectral study indicated the formation of GNPs with a surface plasmon resonance (SPR) band at 547 nm. FTIR analysis of turmeric crude extract and GNPs showed that phenolic groups reduced the gold ions. The FESEM analysis showed the polydisperse morphology of GNPs with average size of 26.6 nm±7.4 nm. The elemental composition determined by EDX re-vealed the presence of gold. The synthesized GNPs can be useful in a variety of applications involving medicine, cosmetics, environment and nutraceutical.

scholarly journals Core-Shell Au@Ag Nanoparticles Synthesized with Polyphenols as Antimicrobial Agents

2021 ◽  
Author(s):  
Jesús Mauro Adolfo Villalobos-Noriega ◽  
Ericka Rodríguez Leon ◽  
César Rodríguez-Beas ◽  
Eduardo Larios-Rodríguez ◽  
Maribel Plascencia-Jatomea ◽  
...  
Keyword(s):  
Growth Kinetic ◽  
Antimicrobial Agents ◽  
Bimetallic Nanoparticles ◽  
Kinetic Curve ◽  
Core Shell ◽  
Root Extract ◽  
X Ray ◽  
Transmission Electron ◽  
Gold Silver ◽  
Vis Spectroscopy

Abstract In this work, we used a sequential method of synthesis for gold-silver bimetallic nanoparticles with core@shell structure (Au@AgNPs). Rumex hymenosepalus root extract (Rh), which presents high content in catechins and stilbenes, was used as reductor agent in nanoparticles synthesis. Size distribution obtained by Transmission Electron Microscopy (TEM) give a diameter mean of 36 nm for Au@AgNPs, and 24 nm for gold nanoparticles (AuNPs). The geometrical shapes of NPs were principally quasi-spherical. The thickness of silver shell over AuNPs are around 6 nm and covered by active biomolecules onto surface. Microstructural characterization included high angle annular dark field images (HAADF) recorded with a scanning transmission electron microscope (STEM), Energy-Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD), UV-Vis Spectroscopy, and Zeta Potential. Also, a growth kinetic curve analysis using the Gompertz model for Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Candida albicans (yeast) were carried out for Au@AgNPs and monometallic AuNPs and AgNPs. Interestingly, Gompertz analysis indicates that Au@AgNPs present a higher effect on the growth kinetic of microorganisms than shown by monometallic nanoparticles.

Synthesis of Al/Cu core–shell particles through optimization of galvanic replacement method in alkaline solution

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Rashid Ali ◽  
Fahad Ali ◽  
Aqib Zahoor ◽  
Rub Nawaz Shahid ◽  
Naeem ul HaqTariq ◽  
...  
Keyword(s):  
Alkaline Solution ◽  
Copper Deposition ◽  
Molar Ratio ◽  
Galvanic Replacement ◽  
Core Shell ◽  
Affecting Factors ◽  
X Ray ◽  
Replacement Method ◽  
Al Powder ◽  
Shell Particles

Abstract In this work, Al/Cu core–shell particles were successfully synthesized through an optimized galvanic replacement method. For this purpose, a uniform and dense copper layer was deposited on aluminum particles in an alkaline solution. The effects of four deposition factors, i. e. (i) molar ratio EDTA-2Na/CuSO4 · 5H2O, (ii) molar ratio CuCl2/Al powder, (iii) pH and (iv) temperature were systematically studied and optimized using the Taguchi orthogonal (L9) method. It was observed that molar ratio EDTA-2Na/CuSO4 · 5H2O and temperature are the most affecting factors in the deposition process. By increasing their levels, copper deposition increases within a specified time. The X-ray diffraction and scanning electron microscopy/ energy-dispersive X-ray spectroscopy results revealed the formation of homogeneous nanostructured Cu shells around Al particles. The results revealed that to achieve maximum copper deposition on Al powder; molar ratio EDTA-2Na. 2H2O/CuSO4. 5H2O, molar ratio CuCl2/Al powder, pH and temperature of the deposition bath should be 2.0, 0.05, 8.8 and 55 °C, respectively.

scholarly journals Structural and Spectroscopic Characterization of PM 597 Dye-Silica Core-Shell Nanoparticles

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Tahani R. Al-Biladi ◽  
A. S. Al Dwayyan ◽  
M. Naziruddin Khan ◽  
Saif M. H. Qaid ◽  
Khalid Al Zahrani
Keyword(s):  
Emission Spectra ◽  
Spectroscopic Characterization ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Silica Core ◽  
Shell Particles ◽  
Average Size ◽  
Core Shell Nanoparticles ◽  
20 Nm

Nanostructured fluorescent pyrromethene (PM) doped-silica core-shell particles were successfully prepared by Stöber process. The average size of the particles was in the range of 10–20 nm measured by TEM micrograph. The atomic structure and morphology of PM 597/SiO2core/shell nanoparticles were studied by AFM and SEM, respectively. Absorption and emission spectra of the PM 597/SiO2core/shell nanoparticles under the UV irradiation were studied and not significantly influenced at the position of peaks. Finally, amplified spontaneous emission (ASE) and photobleaching of dye were examined and found no significant influence on the peaks of PM dye due to the formation of smaller sizes of PM 597/SiO2core/shell nanoparticles. The observed PM 597/SiO2core/shell nanoparticles were different in shapes with smaller size distribution and highly luminescent. Majority of nanoparticles were roughly spherical with many of them aggregated. The less photobleaching of dye core may be due to the protection of pumped energy by SiO2shell and restricts the leakage of dye.

X-ray Absorption Study of Structural Coupling in Photomagnetic Prussian Blue Analogue Core@Shell Particles

2014 ◽  
Vol 26 (8) ◽  
pp. 2586-2594 ◽  
Author(s):  
Daniel M. Pajerowski ◽  
Bruce Ravel ◽  
Carissa H. Li ◽  
Matthieu F. Dumont ◽  
Daniel R. Talham
Keyword(s):  
Prussian Blue ◽  
Core Shell ◽  
Absorption Study ◽  
Structural Coupling ◽  
Prussian Blue Analogue ◽  
X Ray ◽  
Shell Particles ◽  
X Ray Absorption
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