scholarly journals Hybrid Nanoparticles Based on Cobalt Ferrite and Gold: Preparation and Characterization

2021 ◽  
Author(s):  
Svetlana Saikova ◽  
Alexander Pavlikov ◽  
Tatyana Trofimova ◽  
Yuri Mikhlin ◽  
Denis Karpov ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Cobalt Ferrite ◽  
Magnetic Measurements ◽  
Average Particle Size ◽  
Gold Nanoclusters ◽  
Hybrid Nanoparticles ◽  
Gold Deposition ◽  
Average Particle ◽  
X Ray ◽  
Vis Spectroscopy

During the past few decades, hybrid nanoparticles (HNPs) based on a magnetic material and gold have attracted interest for applications in catalysis, diagnostics and nanomedicine. In this paper, magnetic CoFe2O4/Au HNPs with an average particle size of 10–20 nm decorated with 2-nm gold clusters were prepared using methionine as a reducer and an anchor between CoFe2O4 and gold. The obtained nanoparticles were studied by X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy and X-Ray photoelectron spectroscopy (XPS) and UV-Vis spectroscopy techniques. The TEM images of the HNPs obtained after one, six and ten gold deposition cycles showed that the surface of cobalt ferrite was covered with gold nanoclusters, which slightly increased with an increase in the number of gold deposition cycles (from 2.12 ± 0.15 nm after one cycle to 2.46 ± 0.13 nm after ten cycles) without any change in surface density. The magnetic measurements showed that the obtained HNPs possessed typical ferrimagnetic behaviour, which corresponds to that of CoFe2O4 nanoparticles. The toxicity evaluation of the synthesised HNPs on Chlorella vulgaris indicated that they can be applied to biomedical applications such as magnetic hyperthermia, photothermal therapy, drug delivery, bioimaging and biosensing.

scholarly journals Hybrid Nanoparticles Based on Cobalt Ferrite and Gold: Preparation and Characterization

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 705
Author(s):  
Svetlana Saikova ◽  
Alexander Pavlikov ◽  
Tatyana Trofimova ◽  
Yuri Mikhlin ◽  
Denis Karpov ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Cobalt Ferrite ◽  
Magnetic Measurements ◽  
Average Particle Size ◽  
Hybrid Nanoparticles ◽  
Gold Deposition ◽  
Average Particle ◽  
X Ray ◽  
Au Clusters ◽  
Vis Spectroscopy

During the past few decades, hybrid nanoparticles (HNPs) based on a magnetic material and gold have attracted interest for applications in catalysis, diagnostics and nanomedicine. In this paper, magnetic CoFe2O4/Au HNPs with an average particle size of 20 nm, decorated with 2 nm gold clusters, were prepared using methionine as a reducer and an anchor between CoFe2O4 and gold. The methionine was used to grow the Au clusters to a solid gold shell (up to 10 gold deposition cycles). The obtained nanoparticles (NPs) were studied by X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-Ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy techniques. The TEM images of the obtained HNPs showed that the surface of cobalt ferrite was covered with gold nanoclusters, the size of which slightly increased with an increase in the number of gold deposition cycles (from 2.12 ± 0.15 nm after 1 cycle to 2.46 ± 0.13 nm after 10 cycles). The density of the Au clusters on the cobalt ferrite surface insignificantly decreased during repeated stages of gold deposition: 21.4 ± 2.7 Au NPs/CoFe2O4 NP after 1 cycle, 19.0 ± 1.2 after 6 cycles and 18.0 ± 1.4 after 10 cycles. The magnetic measurements showed that the obtained HNPs possessed typical ferrimagnetic behavior, which corresponds to that of CoFe2O4 nanoparticles. The toxicity evaluation of the synthesized HNPs on Chlorella vulgaris indicated that they can be applied to biomedical applications such as magnetic hyperthermia, photothermal therapy, drug delivery, bioimaging and biosensing.

scholarly journals Olive Leaves as Biotemplates for Enhanced Solar-Light Harvesting by a Titania-Based Solid

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1057
Author(s):  
Jesús Hidalgo-Carrillo ◽  
Juan Martín-Gómez ◽  
M. Carmen Herrera-Beurnio ◽  
Rafael C. Estévez ◽  
Francisco J. Urbano ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Average Particle Size ◽  
Solar Irradiation ◽  
Bet Surface Area ◽  
Resonance Spectroscopy ◽  
Average Particle ◽  
Olive Leaves ◽  
Sem Images ◽  
X Ray

Olive leaves (by-product from olive oil production in olive mills) were used as biotemplates to synthesize a titania-based artificial olive leaf (AOL). Scanning electron microscopy (SEM) images of AOL showed the successful replication of trichomes and internal structure channels present in olive leaves. The BET surface area of AOL was 52 m2·g−1. X-ray diffraction (XRD) and Raman spectra revealed that the resulting solid was in the predominantly-anatase crystalline form (7.5 nm average particle size). Moreover, the synthesis led to a red-shift in light absorption as compared to reference anatase (gap energies of 2.98 and 3.2 eV, respectively). The presence of surface defects (as evidenced by X-ray photoelectron spectroscopy, XPS, and electron paramagnetic resonance spectroscopy, EPR) and doping elements (e.g., 1% nitrogen, observed by elemental analysis and XPS) could account for that. AOL was preliminarily tested as a catalyst for hydrogen production through glycerol photoreforming and exhibited an activity 64% higher than reference material Evonik P25 under solar irradiation and 144% greater under ultraviolet radiation (UV).

Multiferroic Bismuth Ferrite Nanoparticles: Rapid Sintering Synthesis, Characterization, and Optical Properties

2010 ◽  
Vol 152-153 ◽  
pp. 81-85
Author(s):  
Xiong Wang ◽  
Yin Lin ◽  
Jin Guo Jiang
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Optical Properties ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray ◽  
Bifeo3 Nanoparticles ◽  
Rapid Sintering

The homogeneous multiferroic BiFeO3 nanoparticles with average particle size of 85 nm have been successfully synthesized by a simple sol-gel route. The prepared sample was characterized by a variety of techniques, such as X-ray diffractometry, thermogravimetric analysis and differential thermal analysis, differential scanning calorimeter analysis, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The obtained results shows that rapid sintering and subsequently quenching to room temperature are the two vital important factors for the preparation of pure BiFeO3. The magnetic phase transition (TN = 369 °C) and the ferroelectric phase transition (TC = 824.5 °C) were determined, revealing the antiferromagnetic and ferroelectric nature of the as-prepared BiFeO3 nanoparticles. The optical properties of the nanopowders were investigated. The strong band-gap absorption at 486 nm (2.55 eV) of the BiFeO3 nanoparticles may bring some novel applications.

Facile Synthesis and Characterization of Spinel NiFe2O4 Nanoparticles and Studies of Their Photocatalytic Activity for Oxidation of Alcohols

2020 ◽  
Vol 12 (3) ◽  
pp. 357-365 ◽  
Author(s):  
Xiangrong Ma ◽  
Rui Dang ◽  
Jieying Liu ◽  
Fang Yang ◽  
Huigui Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray ◽  
Bet Analysis ◽  
Oxidation Of Alcohols ◽  
20 Nm ◽  
Adsorption Desorption

In this paper, we report a novel and facile approach for the synthesis of spinel NiFe2O4 nanoparticles and studies of its photocatalytic activity for oxidation of alcohols. The as-synthesized catalyst was thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental mapping, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and N2 adsorption–desorption isotherm (BET) analysis. The TEM image reveals cubic shapes with an average particle size of 10–20 nm. The as-synthesized spinel NiFe2O4 has proved to be an excellent photocatalyst for oxidation of alcohol to the aldehyde with a conversion of 80% and selectivity of 99%. The catalyst has also proved to be noteworthy as it does not loss its catalytic activity even after five cycles of reuse.

Preparation, characterization and dechlorination property of nano Pd-Ni/γ-Al2O3 bimetallic catalyst

2019 ◽  
Vol 12 (06) ◽  
pp. 1951003 ◽  
Author(s):  
Yu Zhang ◽  
Yiyang Wang ◽  
Yalong Liao ◽  
Muyuan Guo ◽  
Gongchu Shi
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Bimetallic Catalyst ◽  
Average Particle Size ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
Emission Spectrometry ◽  
Average Particle ◽  
Plasma Atomic Emission Spectrometry ◽  
X Ray

Nano Pd-Ni/[Formula: see text]-Al2O3 bimetallic catalyst was prepared by chemical precipitation method enhanced with ultrasonic wave. The influence of dosage of dispersant, ultrasonic intensity and mass ratio of Pd to Ni on the dechlorination property of the catalyst obtained was investigated in detail. The appearance morphology, composition and structure of the catalysts prepared were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption, while the specific surface area was determined using the Brunauer–Emmett–Teller (BET) isotherm and the chemical composition of active gradients was tested with inductively coupled plasma-atomic emission spectrometry (ICP-AES). Results indicate that the nano Pd-Ni/[Formula: see text]-Al2O3 bimetallic catalyst prepared has uniform distribution of active ingredients with an average particle size of 4.91[Formula: see text]nm, and the chlorine content of shellac dechlorinated with the catalyst obtained is 0.34[Formula: see text]wt.% which is lower than that reported in the literature, meaning the perfect dechlorination property of the catalyst.

scholarly journals Effect of Synthesis Method on Antibacterial and Antibiofilm Activity Properties of BaFeO3-δ Perovskite Nanomaterials

2021 ◽  
Author(s):  
eid khalaf ◽  
E. K. Abdel-Khalek ◽  
Ahmed. A. Askar ◽  
M. A. Motawea ◽  
Mohamed A. Aboelnasr ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Rietveld Analysis ◽  
Antibiofilm Activity ◽  
Average Particle ◽  
X Ray ◽  
Valence States ◽  
Fe Ions

Abstract BaFeO3-δ perovskite nanomaterials have been synthesized by two different methods: co-precipitation (Cop) and sol-gel (Sol) methods. Rietveld analysis of the X-Ray diffraction (XRD) shows that the samples are crystallized in rhombohedral perovskite structure with space group R3c. Scanning electron microscope (SEM) of these samples showed the agglomerations of various particles. Dynamic light scattering (DLS) showed that the average particle size of BaFeO3-Cop sample is larger than that of BaFeO3-Sol sample. The amount of oxygen deficient (δ) and the valence states of Fe ions in these samples were determined from Mössbauer spectroscopy. X-ray photoelectron spectroscopy (XPS) shows the elemental compositions and surface electronic states of these samples. The thermal, optical and magnetic properties of these samples depend on the amount of oxygen deficient (δ) and the valence states of Fe ions. Furthermore, the antibacterial and antibiofilm activity of these samples was systematically investigated. The present results suggest that BaFeO3-δ superparamagnetic perovskite can be used as antibacterial and antibiofilm agent.

scholarly journals Influence of Cr2O3 Nanoparticles on the Structural, Optical, Thermal and Electrical Properties of PEO/CMC Nanocomposites

2021 ◽  
Author(s):  
Laila Gaabour
Keyword(s):  
Energy Gap ◽  
Average Particle Size ◽  
Nanocomposite Films ◽  
Average Particle ◽  
Cole Plot ◽  
Optical Energy Gap ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Cr2o3 Nanoparticles ◽  
A Charge

Abstract In the present paper, different concentrations of chromium oxide (Cr2O3) nanoparticles were incorporated within PEO/CMC polymer blend to produce nanocomposite films using the casting method. The X-ray diffraction was performed on PEO/CMC-Cr2O3 nanocomposites. The main X-ray peaks of Cr2O3 were observed and defined as cubic structure and orthorhombic shape with an average particle size of the Cr2O3 ~ 50-80 nm. The decrease of some IR bands after the addition of Cr2O3 nanoparticles was found attributed to the interactions between PEO/CMC and Cr2O3. Effect of Cr2O3 nanoparticles on optical properties such as absorbance and optical energy gap (Eg) were characterized using UV-Vis spectroscopy. The Eg was reduced after the addition of Cr2O3 nanoparticles. The AC conductivity (sac), dielectric constant (ε′), dielectric loss (ε′′) and the dielectric modulus (M′ and M′′) were calculated at frequency range 0.1 Hz-7 GHz. The increases of direct conductivity (σdc) imply that the free charge density or of the charge mobility that results. The estimated values of both ε′ and ε′′ were decreased with increases of frequency. The addition of Cr2O3 nanoparticles causes the formation of a charge-transfer complex. The Cole-Cole plot between (M′ and M′′) shows a semi-circular shape confirm discuses according to a non‐Debye method.

scholarly journals In-flight Synthesis of Nanosized ZrC Particles from Various Precursors in RF Thermal Plasma

2021 ◽  
Author(s):  
Alejandro Martiz ◽  
Zoltán Károly ◽  
Eszter Bódis ◽  
Péter Fazekas ◽  
Miklós Mohai ◽  
...  
Keyword(s):  
Thermal Plasma ◽  
Photoelectron Spectroscopy ◽  
Average Particle Size ◽  
Reaction System ◽  
Spherical Shape ◽  
Molar Ratio ◽  
Average Particle ◽  
X Ray ◽  
Temperature Range ◽  
Rf Thermal Plasma

Synthesis of zirconium carbide (ZrC) powder was investigated applying a non-conventional atmospheric radiofrequency (RF) thermal plasma process. In one case, zirconium dioxide (ZrO2) was reacted with solid carbon or with methane with varying molar ratio. In the other, zirconium-propoxide (NZP), containing both constituents, was thermally decomposed in the Ar plasma. Temperature-dependent thermodynamic analysis was performed in the 500-5500 K temperature range to estimate the formation of possible equilibrium products for each reaction stoichiometry. Broad temperature range exists for the stability of solid ZrC for each explored reaction system. In accordance with this prediction, X-ray diffraction studies detected the ZrC as the major phase in all the prepared powders. The yield of particular runs ranged from 39 % to 98 %. Practically, full conversion was typical for the case of NZP precursor, however only partial conversion could be detected in ZrO2 reactions. The average particle size of the powders falls between 10 nm and 100 nm depending on the type of the reaction systems (either calculated from the specific surface area or derived from broadening the XRD reflections). The transmission electron micrographs indicated mostly globular shape of the nanosize particles. Quantitative analysis of the surface of the powders by X-ray photoelectron spectroscopy revealed the presence of oxygen and carbon. Evaluating the spectra of the powders prepared from NZP, and taking in the account its spherical shape, a ZrC core covered by a very thin (≈1.0 nm) ZrO2 layer may be accounted for the measured oxygen and a thicker carbonaceous layer.

Formation features of zink titanate by electric explosion dispersion of titanium and zinc wires in an oxygen-containing atmosphere

2021 ◽  
pp. 38-43
Author(s):  
O.V. Bakina ◽  
◽  
N.V. Svarovskaya ◽  
A.V. Pervikov ◽  
V.R. Chzhou ◽  
...  
Keyword(s):  
Titanium Oxide ◽  
Photoelectron Spectroscopy ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Decomposition Reaction ◽  
Electric Explosion ◽  
Average Particle ◽  
Zinc Titanate ◽  
X Ray ◽  
High Antibacterial Activity

In present work, we have synthesized, for the first time, zinc titanate nanoparticles by electric explosion of titanium and zinc wires in an oxygen-containing atmosphere (argon - oxygen 20 vol. %). As-synthesized nanoparticles nanoparticles were characterized using transmission electron microscopy, X-ray analysis, and X-ray photoelectron spectroscopy. The particles have a spherical shape and an average particle size of 82 nm. The phase composition is presented by zinc titanate and a small amount of titanium oxide, which corresponds to the phase diagram of the TiO2-ZnO system. The photocatalytic activity of the synthesized nanoparticles was studied in the decomposition reaction of a model dye methylene blue and it was found that it was higher than that of titanium oxide nanoparticles obtained by electric explosion of a titanium wire in an oxygen-containing atmosphere. In addition, the synthesized nanoparticles demonstrated high antibacterial activity against MRSA bacteria.

scholarly journals As(III) Removal from Aqueous Solution by Calcium Titanate Nanoparticles Prepared by the Sol Gel Method

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 733 ◽  
Author(s):  
Rocío Tamayo ◽  
Rodrigo Espinoza-González ◽  
Francisco Gracia ◽  
Ubirajara Pereira Rodrigues-Filho ◽  
Marcos Flores ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photoelectron Spectroscopy ◽  
Arsenic Removal ◽  
Sol Gel ◽  
Average Particle Size ◽  
Equilibrium Adsorption ◽  
Batch Adsorption ◽  
Average Particle ◽  
Spectroscopy Analysis ◽  
X Ray

Arsenic (As) contamination of water is a serious problem in developing countries. In water streams, arsenic can be as As(V) and As(III), the latter being the most toxic species. In this work, an innovative adsorbent based on CaTiO3 nanoparticles (CTO) was prepared by the sol-gel technique for the removal of As(III) from aqueous solution. X-ray diffraction of the CTO nanoparticles powders confirmed the CTO phase. Transmission electron microscopy observations indicated an average particle size of 27 nm, while energy dispersive X-ray spectroscopy analysis showed the presence of Ca, Ti, and O in the expected stoichiometric amounts. The surface specific area measured by Brunauer, Emmett, and Teller (BET) isotherm was 43.9 m2/g, whereas the isoelectric point determined by Zeta Potential measurements was at pH 3.5. Batch adsorption experiments were used to study the effect of pH on the equilibrium adsorption of As(III), using an arsenite solution with 15 mg/L as initial concentration. The highest removal was achieved at pH 3, reaching an efficiency of up to 73%, determined by X-ray fluorescence from the residual As(III) in the solution. Time dependent adsorption experiments at different pHs exhibited a pseudo-second order kinetics with an equilibrium adsorption capacity of 11.12 mg/g at pH 3. Moreover, CTO nanoparticles were regenerated and evaluated for four cycles, decreasing their arsenic removal efficiency by 10% without affecting their chemical structure. X-ray photoelectron spectroscopy analysis of the CTO surface after removal experiments, showed that arsenic was present as As(III) and partially oxidized to As(V).

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